Condition

Psoriasis

Psoriasis is a long-term condition in which the immune system speeds up skin cell growth, leaving thick, scaly patches. It is not contagious and it is not caused by anything you did. Treatment has changed enormously, and clear skin is now a realistic goal for most people.
Dr. Schwarz, MD · Board-certified dermatologistLast reviewed September 8, 2026
16:9 hero for Psoriasis. Never cropped: the tone strip and the corner logo depend on the full frame.

Start here

If you were told years ago that psoriasis is something you learn to live with, that is out of date — for moderate and severe disease, treatments now clear the skin almost completely in a large share of people, and the bar to qualify is low. I ask about joints at every visit, because around one in three people develop psoriatic arthritis and damage that goes unnoticed does not reverse. Tell me about morning stiffness lasting more than half an hour, a swollen finger or toe, or heel pain. The same inflammation is also linked with heart disease, metabolic disease and depression, so keep a primary care doctor alongside the dermatologist.

— Dr. Schwarz, Board Certified Dermatologist

Key Facts

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How commonRoughly 2 to 3 percent of people worldwide
Who gets itAny age, with two common starting points - the late teens to twenties, and the fifties to sixties. Men and women about equally
Curable or managedManaged - there is no cure, but completely clear skin is a realistic goal with modern treatment
Prescription neededUsually yes. Over-the-counter products help the mildest patches only
Time to improveA few weeks for creams, and about 3 months before judging a systemic medicine

What It Is

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Psoriasis is a long-term condition where the immune system misfires and drives skin cells to multiply far too fast. The result is raised, thickened plaques covered in scale, most often on the elbows, knees, scalp, lower back and the crease between the buttocks. Plaques are usually symmetrical — one elbow involved means the other usually is too — with sharp, well-defined borders, unlike eczema.

About half of people with psoriasis itch, sometimes badly, and plaques crack and bleed, especially over joints and on the hands and feet. Nails are involved in a large share of cases — small pits, oil-drop discoloration, thickening, or separation of the nail from the nail bed.

Plaque psoriasis is much the commonest variant. Guttate psoriasis is a sudden shower of drop-shaped spots, often in children and young adults after a strep throat. Inverse psoriasis sits in the folds — breasts, armpits, groin — smooth and shiny rather than scaly. Pustular psoriasis makes sterile pus-filled spots, sometimes only on palms and soles. Erythrodermic psoriasis, where most of the skin turns red and inflamed, is uncommon and a medical emergency.

Psoriasis affects more than your skin. About one in three people develop psoriatic arthritis, and the same inflammation raises the risk of heart disease, metabolic disease and depression. None of it is contagious.

Symptoms

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Thick scaly patches

Plaque

Well-defined raised patches with thick silvery scale, typically on elbows, knees, the lower back and the scalp. On deeper skin tones the patches read as purple, gray or dark brown rather than red. This is by far the most common form.
Small drop-like spots

Guttate

Many small, scaly, teardrop-shaped spots appearing quickly across the trunk and limbs, often a week or two after a throat infection. It is most common in children and young adults. It may clear completely or later turn into the plaque form.
Shiny patches in the folds

Inverse

Smooth, shiny, red or dark patches in the armpits, groin, under the breasts and between the buttocks, with little or no scale because the area is moist. It is often mistaken for a fungal infection. It is sore rather than itchy where skin rubs.

How It Looks by Skin Tone

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Two thick, sharply bordered plaques on a knee on fair light skin. They are salmon-pink to red with loose silvery-white scale on top.Two thick, sharply bordered plaques on a knee on medium olive-tan skin. They are dusky pink-brown with silvery-gray scale on top that stands out more than the color beneath.Two thick, sharply bordered plaques on a knee on brown skin. The plaques are violet-brown rather than red, with silvery-gray scale on top.Two thick, sharply bordered plaques on a knee on deep dark brown skin. The plaques are dark brown, close to the surrounding color, and the silvery-gray scale on top is the clearest feature.
LightMediumBrownDeep

On deeper skin tones, plaques are often violet, gray-brown or dark brown rather than pink or red, and the scale can look silvery-gray against them. Severity scores were built around how red skin looks, so psoriasis on deeper skin tones is routinely rated milder than it is and treated less aggressively. Thickness, scale, how much of the body is covered and how much it affects daily life are more reliable measures than color.

Two things follow. Diagnosis is often delayed, and more of the body is involved by the time it is made — scalp involvement in particular tends to be extensive at first presentation. Getting an accurate assessment sometimes means asking directly whether severity was judged on redness alone. After plaques clear, the skin often does not look normal straight away. Psoriasis on deeper skin tones commonly leaves flat dark marks, sometimes pale ones, and they can take six to twelve months to even out — much longer than the plaques took to settle. That is normal healing, not failed treatment, and worth knowing in advance. Daily sunscreen helps the dark marks fade faster. Phototherapy still works well on deeper skin tones. More pigment absorbs more of the light before it reaches the target, so treatment starts at a higher dose and may take a few more sessions.

Where It Shows Up

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Front view of a whole body with red marks on the outside of both elbows, on both knees and down both shins.
The outside of the elbows and knees
The classic sites, and the way it sits is part of the diagnosis: on the outside of the joint, not in the crease. Eczema does the opposite. It is usually symmetrical, so if one elbow is involved the other normally is too.
Front view of a head with red marks across the scalp, along the hairline and behind both ears.
Scalp and hairline
The scalp is involved in about half of people, and the plaques often run past the hairline onto the forehead and behind the ears — which is one of the things that separates it from dandruff, and the reason a hairline edge is worth looking at.
Back view of a whole body with red marks across the lower back, in the crease between the buttocks, on the middle back and on both elbows.
Lower back and the crease between the buttocks
The lower back and the crease between the buttocks are common and easily missed. So are the folds, the palms, the soles, the face and the genitals — those sites matter more than their size suggests, because they affect daily life out of proportion to the area involved. Nails are affected in a large share of cases.

What Happens in the Skin

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This is what is going wrong under the skin, in the order it happens. Click a step to see it.

How Psoriasis happens
Skin basics
BARRIEREPIDERMISDERMIS28 days4-6 daysDEAD SKIN0NORMAL SKIN1OVERACTIVE IMMUNE SIGNALING2INFLAMMATION INCREASES3SKIN CELLS MULTIPLY FAR TOO FAST4THICK SCALE AND A DAMAGED BARRIER

In healthy skin, a cell made at the base of the epidermis takes about a month to reach the surface. By the time it arrives it is flat and dead, and it sheds one cell at a time, so nothing piles up. The immune system stays quiet unless there is something to fight.

Immune cells in the skin switch on when there is nothing to fight and release signals such as TNF, interleukin-17 and interleukin-23. These are the messages that tell the skin it is under attack, and they are what biologic injections are built to block.

Inflammation brings increased blood flow to the area.

Told to behave as though the skin is injured, cells at the base of the epidermis divide far faster than normal. A journey to the surface that should take about a month is finished in a few days, so the cells arrive immature and still stuck together.

The immature cells pile up instead of shedding invisibly, which builds the raised plaque and the silvery scale. Blood vessels underneath multiply and widen, which is why picking the scale off leaves pinpoint bleeding, and why plaques crack over joints.

The outer film of dead cells and oil. It holds water in and keeps irritants out, and it is thinner than a sheet of paper. Almost every dry, itchy, stinging skin problem starts here.

The outer layer, and the only one anything in a jar reaches. It renews itself constantly: a cell made at the bottom takes about a month to reach the surface and flake off. Most of what a skincare product does, it does here.

The living layer underneath, holding the blood vessels, the nerves and the collagen. It is where lasting change happens and it is hard to reach: most of what is sold for the skin never gets this far.

Psoriasis is immune-driven. Particular immune cells in the skin become overactive and release signaling proteins — among them TNF, interleukin-17 and interleukin-23 — that tell the skin to behave as though it is under attack. It is not an allergy and not an infection.

The visible consequence is speed. Skin cells normally take around a month to travel from the base of the epidermis to the surface and shed invisibly. In a plaque they do it in a few days, arriving immature and still stuck together, and they pile up as thick, silvery scale. Blood vessels beneath the plaque also multiply and dilate, which is why plaques bleed as pinpoint dots when scale is picked off.

Genes set the stage. Psoriasis runs in families, and several genes affecting immune regulation have been identified — but genes alone are not enough. Something usually sets it off — a strep throat, a skin injury, a stressful stretch, a new medicine, smoking, or weight gain. Once started, the inflammation sustains itself, which is why psoriasis persists instead of resolving like an ordinary rash.

None of it is caused by diet, hygiene or anything you did.

Risk Factors

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Most of what raises the risk is out of your hands.

Inherited
Family history
The strongest single factor. One parent raises your risk substantially; both raise it further.
Inherited
Certain immune-system genes
Several identified; particular ones go with psoriasis that starts young or the guttate form.
Lifestyle
Carrying extra weight
Obesity raises the risk and makes psoriasis more severe and harder to treat.
Lifestyle
Smoking
Linked with developing psoriasis, more severe disease, and the pustular form on palms and soles.
Lifestyle
Heavy alcohol use
More severe disease, and treatments that work less well.
Other health conditions
Streptococcal throat infection
A well-established trigger for guttate psoriasis, mostly in children and young adults.
Other health conditions
HIV
Psoriasis is more common and often more severe in people with untreated HIV.
Other health conditions
Some medicines
Lithium, beta blockers, antimalarials, and stopping oral steroids abruptly. Never stop a prescribed medicine on your own. Ask your doctor.
Skin injury & stress
Injury to the skin
Cuts, scrapes, sunburn, tattoos and surgical scars can produce plaques along the line of injury — the Koebner phenomenon.
Skin injury & stress
Stress
Not a cause on its own, but a common trigger for a first episode and later flares.

Course

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Psoriasis is lifelong and runs in cycles rather than progressing steadily. Quiet stretches alternate with active ones, and the pattern is individual — winter for some, stress or infections for others, no identifiable reason for many.

First appearanceOften after a trigger
The start is usually traceable

The first episode can usually be traced to a trigger. In children and young adults, guttate psoriasis often follows a strep throat by one to three weeks.

After a guttate episodeWeeks to months
Many clear completely

Guttate psoriasis often clears within a few months and may never return. Some people develop plaque psoriasis later.

Established plaque psoriasisYears, in cycles
It usually persists

Once established it usually stays. Long remissions happen, some lasting years, but cannot be predicted. Severity is not fixed either — a few small patches at twenty can mean widespread disease at forty, or the reverse, and weight gain, smoking and stopping treatment all push the wrong way.

JointsUsually years after the skin
Around one in three develop arthritis

Psoriatic arthritis usually appears years after the skin changes, though it can come first. Damage done before it is recognized does not reverse, so report persistent joint pain, swelling or prolonged morning stiffness rather than waiting.

With treatmentLong term
The course changes, but there is no cure

Skin can be kept clear or nearly clear for years, treatment stepped up and down as the disease shifts. Two situations need urgent care, not a routine appointment — widespread redness covering most of the body, and a sudden outbreak of pus-filled spots with fever or feeling unwell.

What Makes It Better & Worse

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Psoriasis is four problems at once — overactive immune signaling, skin cells multiplying too fast, thick scale and a damaged barrier, and triggers that set the loop off. The right treatment depends on which step is driving it — stuck-down scale needs different treatment from widespread disease.

What is driving yours?

FAT28 days4-6 daysDEAD SKINBARRIEREPIDERMISDERMIS

Immune cells in the skin switch on when there is nothing to fight and release signals such as TNF, interleukin-17 and interleukin-23. These are the messages that tell the skin it is under attack, and they are what biologic injections are built to block.

Told to behave as though the skin is injured, cells at the base of the epidermis divide far faster than normal. A journey to the surface that should take about a month is finished in a few days, so the cells arrive immature and still stuck together.

The immature cells pile up instead of shedding invisibly, which builds the raised plaque and the silvery scale. Blood vessels underneath multiply and widen, which is why picking the scale off leaves pinpoint bleeding, and why plaques crack over joints.

What helps

  • A vitamin D analog with a steroid The standard first-line prescription.
  • A topical steroid matched to the site Strong for thick plaques, milder on face and folds.
  • Narrowband UVB phototherapy Among the best for widespread disease.
  • Some natural sunlight Short, regular exposure helps. Burning triggers plaques.
  • Stopping smoking Improves the disease and how treatments work.
  • Losing weight if you are carrying extra It improves psoriasis alone.
  • Cutting back on alcohol Less severe disease, better response.
  • An oral systemic medicine Methotrexate, acitretin or apremilast when creams and light fail.
  • A biologic medicine Injections blocking one immune signal — the most effective option.
  • Mentioning joint pain to your doctor Damage does not reverse, and it changes treatment.

What makes it worse

  • A strep throat A well-established trigger, especially for guttate.
  • Smoking More severe disease, treatments that work less well.
  • Heavy alcohol use More severe disease, poorer response, drug interactions.
  • Weight gain Worsens psoriasis; some treatments work less well.
  • Stress A frequent trigger for flares, probably via immune signaling.
  • Stopping oral steroids suddenly Rebounds badly, sometimes as pustular.
  • Some medicines Lithium, beta blockers, antimalarials all worsen psoriasis.
  • Infections generally Any significant infection can flare it, not only strep.

What helps

  • Keep treating after it clears Maintenance holds it.
  • Coal tar Old, and still works, particularly for the scalp.
  • A scalp routine that reaches the skin Lift the scale, then treat scalp, not hair.

What makes it worse

  • Stopping treatment once the skin clears Plaques return in weeks to months.

What helps

  • Salicylic acid or urea to lift the scale Medicine cannot get through a crust.
  • A thick plain moisturizer, daily Reduces cracking, itching and scale, helps creams absorb.

What makes it worse

  • Picking or scraping the scale off Leaves raw skin, can seed a plaque.
  • Cold, dry weather and indoor heating Winter is the harder season.

What helps

  • Treating a strep throat Worth testing if sore throats precede flares.

What makes it worse

  • Injury to the skin Cuts, bites, sunburn and tattoos can grow a plaque.

How These Treatments Work

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Treatments for Psoriasis do not all work in the same place. Tap one to see where it acts.

Pick a treatment
Skin basics
BARRIEREPIDERMISDERMIS28 days4-6 daysDEAD SKINSLOWS SKIN CELLS DOWNCALMS THE INFLAMMATIONLIFTS THE SCALEQUIETS THE IMMUNE SIGNALCALMS THE CELLS WITH LIGHT

In a plaque, cells reach the surface in four to six days instead of a month and pile up as scale.

Turns down the reaction driving the redness and the thickness.

Does not treat the plaque, but everything else gets in once the scale is off.

Blocks the specific immune messages driving psoriasis. This is what clears widespread disease.

The same target as a biologic, reached a different way.

The outer film of dead cells and oil. It holds water in and keeps irritants out, and it is thinner than a sheet of paper. Almost every dry, itchy, stinging skin problem starts here.

The outer layer, and the only one anything in a jar reaches. It renews itself constantly: a cell made at the bottom takes about a month to reach the surface and flake off. Most of what a skincare product does, it does here.

The living layer underneath, holding the blood vessels, the nerves and the collagen. It is where lasting change happens and it is hard to reach: most of what is sold for the skin never gets this far.

Over-the-Counter Products

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Everything here you can buy without seeing anyone.

Paula's Choice 2% BHA exfoliant, La Roche-Posay Effaclar cleanser and a CeraVe psoriasis cream pumpLabeled cutaway diagram of a single skin pore, headed Salicylic Acid. The epidermis is a brick-textured band across the top and the dermis is pink below it, with a yellow oil gland at the base of the pore and a small cluster of bacteria inside it. A single dark navy callout line points into the top of the pore: decreases dead cells in pore. There are no other callouts, so the drawing shows one effect where the other ingredient diagrams show two or three.
Moderate evidence
Lifts and dissolves the scale on top of a plaque. That matters because no medicated cream can reach the skin through a thick crust, so this is often the step that makes everything else work. It does nothing to the immune signal underneath, and on large areas it should not be used long term.
Five medicated scalp products on white, including Amazon Basics tar gel, T+Plus, MG217, RoyceDerm and Nizoral16:9 hero for Coal Tar. Never cropped: the tone strip and the corner logo depend on the full frame.
Moderate evidence
An old treatment that genuinely still works, slowing the overactive turnover of skin cells. It is most useful as a scalp shampoo left on for several minutes, and on stubborn plaques on the body. The reasons people give it up are the smell and the staining of clothes and bedding rather than the results.
A thick plain moisturizer
A thick plain moisturizer
Moderate evidence
Plain petroleum jelly or a thick unscented ointment, used daily, reduces cracking, itching and scale and helps prescription creams absorb. Apply it after a bath while the skin is still damp. It will not clear a plaque on its own — this is the base everything else is built on, not the treatment.
Five white jars of 40% urea cream lined up, several also listing 2% salicylic acid16:9 hero for Urea. Never cropped: the tone strip and the corner logo depend on the full frame.
Limited evidence
Softens hard, thickened skin and helps shift scale, which makes it useful on the palms, soles and the thickest plaques. Higher strengths work better here than the low ones sold for dry skin. It can sting on cracked skin, so it goes on intact plaques rather than open fissures.
A plain white ointment tube lying on its side, labeled Hydrocortisone with a blue swoosh16:9 hero for Hydrocortisone. Never cropped: the tone strip and the corner logo depend on the full frame.
Limited evidence
The mildest steroid you can buy, and it is honestly too weak for a thick plaque on an elbow or knee. Where it does help is thin skin — the face, the eyelids and the body folds — used for short stretches. If nothing has changed after two weeks, the answer is a stronger prescription rather than more of this.

Prescriptions

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These need a prescription.

16:9 hero for Calcipotriene. Never cropped: the tone strip and the corner logo depend on the full frame.
Calcipotriene with a steroid
Strong evidence
The standard first prescription for plaques: a vitamin D analog that slows the fast cell turnover, combined with a steroid that settles the inflammation. The two together work better than either alone and allow less steroid overall. It comes as an ointment, a foam or a scalp solution, and it is usually used once a day.
16:9 hero for Clobetasol Propionate. Never cropped: the tone strip and the corner logo depend on the full frame.
Clobetasol Propionate
Strong evidence
A very strong steroid for thick, stubborn plaques on the elbows, knees, palms, soles and scalp, where milder ones simply do not get through. It is used in short bursts of two to four weeks, not continuously. It should never go on the face, the eyelids or the body folds, where it thins the skin quickly.
16:9 hero for Tapinarof. Never cropped: the tone strip and the corner logo depend on the full frame.Diagram: how Tapinarof works in the skin
Strong evidence
A once-daily steroid-free cream that calms the immune signal in the plaque. Its appeal in psoriasis is that it can be used on the face and folds and for long stretches without the skin thinning, and improvement often lasts a while after stopping. It can cause folliculitis and itching where it is applied.
16:9 hero for Roflumilast Cream (Zoryve). Never cropped: the tone strip and the corner logo depend on the full frame.Diagram: how Roflumilast Cream (Zoryve) works in the skin
Strong evidence
Another steroid-free once-daily cream, and one of the few licensed for the body folds, where inverse psoriasis is smooth, sore and difficult to treat safely. It is not greasy, which suits scalp and visible areas. Cost and insurance cover are the usual obstacles rather than how well it works.
16:9 hero for Triamcinolone Acetonide. Never cropped: the tone strip and the corner logo depend on the full frame.Diagram: how Triamcinolone Acetonide works in the skin
Strong evidence
A mid-strength steroid for plaques on the trunk, arms and legs — the everyday workhorse between hydrocortisone and clobetasol. It is often alternated with a vitamin D cream so that the steroid is not used every day. Plaques usually return within weeks of stopping, which is why maintenance is planned rather than improvised.
16:9 hero for Tazarotene. Never cropped: the tone strip and the corner logo depend on the full frame.Diagram: how Tazarotene works in the skin
Moderate evidence
A retinoid gel that thins the plaque and reduces scale, and its benefit tends to hold longer after stopping than a steroid's does. It is irritating on its own, so it is usually paired with a steroid or used every other night. It is not used if you are pregnant or planning to be — ask your doctor.
16:9 hero for Tacrolimus (Protopic). Never cropped: the tone strip and the corner logo depend on the full frame.Diagram: how Tacrolimus (Protopic) works in the skin
Moderate evidence
A steroid-free ointment used on the face, eyelids, genitals and body folds, where psoriasis is thin and smooth and steroids cannot be used for long. It does not thin the skin. It stings or feels warm for the first week or so, which settles, and it works less well on thick plaques elsewhere.
16:9 hero for Desonide. Never cropped: the tone strip and the corner logo depend on the full frame.Diagram: how Desonide works in the skin
Moderate evidence
A mild prescription steroid for psoriasis on the face and in the folds when hydrocortisone is not enough. It is used for short courses and then stepped down to a steroid-free option for maintenance. On elbows, knees and scalp it is too weak to do much.
An orange prescription bottle labeled Sotyktu on its side with white round tablets spilling out16:9 hero for Deucravacitinib (Sotyktu). Never cropped: the tone strip and the corner logo depend on the full frame.
Strong evidence
A once-daily tablet that blocks one specific step in the psoriasis signal. It clears skin better than the older oral options and needs no routine blood monitoring, which is why it is increasingly chosen when creams are not enough. It is not a biologic injection, and it does not treat joint disease as well as they do.
16:9 hero for Methotrexate. Never cropped: the tone strip and the corner logo depend on the full frame.Diagram: how Methotrexate works in the skin
Strong evidence
A long-established once-weekly tablet that damps down the immune overactivity, and it treats psoriatic arthritis at the same time, which is often why it is chosen. It needs regular blood tests for the liver and blood count, and folic acid alongside it. Alcohol is limited, and it is not used in pregnancy — ask your doctor.
An amber pill bottle labeled Cyclosporine tipped over with white tablets spilling out16:9 hero for Cyclosporine. Never cropped: the tone strip and the corner logo depend on the full frame.
Strong evidence
The fastest-acting option, which makes it the rescue treatment for a severe flare or erythrodermic psoriasis. It works within weeks. It is deliberately short-term, usually under a year, because it raises blood pressure and can damage the kidneys, and both are checked throughout.
An amber pill bottle labeled Otezla tipped over with white tablets spilling out16:9 hero for Apremilast (Otezla). Never cropped: the tone strip and the corner logo depend on the full frame.
Moderate evidence
A twice-daily tablet that clears skin less completely than the newer options but needs no blood monitoring at all, which suits people who cannot or will not have regular tests. It is often used for scalp, palm and sole psoriasis. Nausea, loose stools and headache are common in the first few weeks and usually settle.
An amber prescription bottle lying on its side on a white background with a plain white label reading Acitretin, and six small round white tablets spilled out in front of it.
Acitretin
Moderate evidence
An oral retinoid, most useful for pustular psoriasis on the palms and soles and often combined with light treatment. It does not suppress the immune system, which suits people who cannot take something that does. It causes dry lips and eyes and raised cholesterol, and it must not be used by anyone who could become pregnant for three years afterward.
16:9 hero for Prednisone. Never cropped: the tone strip and the corner logo depend on the full frame.Diagram: how Prednisone works in the skin
Weak evidence
Steroid tablets clear psoriasis quickly and then it comes back worse, sometimes as the pustular form, when they are stopped. For that reason they are not used to treat psoriasis. They are on this list because they are still occasionally prescribed for a flare, and because you should never stop a course on your own — ask the doctor who prescribed it.
A gray autoinjector pen labeled Skyrizi with a teal button, lying on a plain pale background16:9 hero for Risankizumab (Skyrizi). Never cropped: the tone strip and the corner logo depend on the full frame.
Strong evidence
A biologic that blocks interleukin-23, given as four injections a year once the starting doses are done. It is where most people begin now: it clears skin as completely as anything available, it holds that clearance over years, and the dosing is the easiest of the group to live with. Tuberculosis and hepatitis screening happens before starting, and there is a real but modest increase in some infections.
A white injector pen on a white background, with a plain white label reading Bimzelx and a blue swoosh beneath it.
Bimekizumab (Bimzelx)
Strong evidence
Blocks interleukin-17A and interleukin-17F, two signals instead of one. In head-to-head trials it leaves more people with completely clear skin, and gets there faster, than any other biologic it has been tested against. The trade-off is oral thrush, which is common enough that it is discussed before starting, and like the other interleukin-17 drugs it is avoided in inflammatory bowel disease.
A white injector pen on a white background, with a plain white label reading Cosentyx and a blue swoosh beneath it.
Secukinumab (Cosentyx)
Strong evidence
Blocks interleukin-17A, and it clears skin fast — often within weeks rather than months. Ixekizumab (Taltz) works the same way, and the choice between the two is mostly practical. Either is a common pick when the scalp, palms, soles or nails are badly affected, and both treat psoriatic arthritis, but they are avoided in inflammatory bowel disease, which they can worsen.
A white injector pen on a white background, with a plain white label reading Stelara and a blue swoosh beneath it.
Ustekinumab (Stelara)
Strong evidence
An older biologic that blocks interleukin-12 and interleukin-23, given four times a year. It does not clear skin as completely as the newer options, which is why it is seldom first choice now, but it has the longest safety record of the group and biosimilar versions have made it one of the cheapest ways to be on a biologic at all.
A silver and dark pink autoinjector pen labeled Humira lying on a white background16:9 hero for Adalimumab (Humira). Never cropped: the tone strip and the corner logo depend on the full frame.
Strong evidence
The oldest of the group, blocking TNF, injected every two weeks. Newer options clear skin more completely, so it is rarely the first choice for skin alone, but it has decades of safety data behind it, it treats psoriatic arthritis well, and biosimilar versions have made it cheap. Screening for tuberculosis and hepatitis is done before starting.

Procedures

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These are done in the office, usually over several visits.

16:9 hero for Phototherapy. Never cropped: the tone strip and the corner logo depend on the full frame.16:9 hero for Narrowband UVB Phototherapy. Never cropped: the tone strip and the corner logo depend on the full frame.
Strong evidence
Narrowband UVB, given two or three times a week in a clinic, is one of the most effective options for psoriasis that covers too much skin for creams. It suppresses nothing in the rest of the body, which is why it suits pregnancy and people who cannot take systemic medicines. The commitment is the difficulty: it means repeated trips over two to three months.
16:9 hero for Excimer Laser. Never cropped: the tone strip and the corner logo depend on the full frame.Diagram: how Excimer Laser works in the skin
Moderate evidence
Delivers the same kind of UVB light, but aimed only at the plaques, so a higher dose can be used and normal skin is spared. It suits a handful of stubborn patches, or psoriasis on the scalp, elbows and knees, rather than widespread disease. It usually takes several short sessions.
A gloved clinician injecting a raised lump on a patient's shoulder with a small syringeA small clear glass vial with a metal crimped cap lying on a white background, with a clear plastic syringe and a fine sheathed needle resting against it.
Limited evidence
A small amount of steroid injected directly into one thick plaque that has refused to shift, or into the nail fold for nail psoriasis. It works where cream cannot get through. It is used sparingly, because repeated injections can leave a dent or a pale mark in the skin, and it is not a treatment for anything widespread.
A patient lying under a blue LED light panel with their eyes covered16:9 hero for LED Light Therapy. Never cropped: the tone strip and the corner logo depend on the full frame.
Weak evidence
Home red and blue LED devices are not the same thing as narrowband UVB, and there is little evidence they clear plaques. Tanning beds are not a substitute either, and they carry a skin cancer risk. If light treatment is the right direction, the version worth having is the medical one, prescribed and dosed.

When to See a Dermatologist

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Get seen early — almost everything that works is prescription-only, and the assessment covers more than skin. Book if you have thick, scaly patches with sharp edges that moisturizer has not shifted, if psoriasis is on your scalp, nails, hands, feet, face or genitals, if it covers more than a few patches, if it itches or cracks enough to affect sleep or work, if a month of over-the-counter treatment has done nothing, or if you feel low or withdrawn because of it. Mention any joint pain, swollen fingers or toes, heel pain, or morning stiffness over half an hour — that is how psoriatic arthritis is caught early, and joint damage does not reverse. Get urgent care the same day if most of your skin turns red, hot, painful and you feel unwell or shivery, or if you develop a sudden widespread outbreak of small pus-filled spots with fever. Both are rare emergencies.

— Dr. Schwarz, Board Certified Dermatologist

Complications

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Psoriatic arthritis

Around one in three people with psoriasis develops arthritis from the same inflammation, usually years after the skin changes. The signs are joint pain and swelling, a whole finger or toe swelling up, heel or lower back pain, and morning stiffness lasting more than half an hour. Damage done before it is recognized does not reverse, so it is worth mentioning early even if it seems unrelated to your skin.

Nail Psoriasis

Nails are involved in a large share of cases, showing small pits, an oily yellow-brown discoloration under the nail, thickening, crumbling, or the nail lifting away from the bed. It is slow to treat because the nail has to grow out, and it is strongly linked with psoriatic arthritis, so it is worth telling your doctor about rather than covering up.

Erythrodermic and pustular flares

Two uncommon flares that are medical emergencies. In one, most of the skin becomes red, hot and painful and the body struggles to hold its temperature and fluids. In the other, crops of small sterile pus-filled spots appear, often with fever and feeling unwell. Both need same-day care. Stopping steroid tablets suddenly is one known trigger, which is why psoriasis is not treated with them.

Lookalikes

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Eczema

Both are itchy, scaly and long-running, and both turn up on the arms and legs. Eczema has soft, blurred edges, often weeps or crusts, and prefers the inside of the elbows and behind the knees. Psoriasis has sharp borders and thicker silvery scale, and sits on the outside of the same joints. Eczema almost always itches; only about half of psoriasis does.

Seborrheic Dermatitis

On the scalp the two are hardest to separate, and some people have both. Seborrheic dermatitis is greasy yellow scale with a soft edge, and it favors the sides of the nose, the eyebrows and the middle of the chest. Scalp psoriasis is thicker, drier, silvery-white, sharply bordered, and it crosses past the hairline onto the forehead and behind the ears.

Ringworm

A single round scaly patch with a raised edge can look like one plaque of psoriasis, and this mix-up matters, because steroid creams make a fungal infection spread. Ringworm is usually one or two patches rather than a symmetrical pattern, the middle of the patch clears while the rim advances, and there are no psoriasis clues elsewhere on the nails, scalp or buttock crease. A scraping settles it.

Myths

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  • "Psoriasis is contagious." It is not, in any way. You cannot catch it by touching a plaque, sharing a towel or swimming in the same pool. It is an immune condition, not an infection — and the most damaging misunderstanding people run into.
  • "It is just very dry skin." Moisturizer helps, which is where the confusion comes from, but dryness is not the cause. Plaques are built by an overactive immune signal driving skin cells several times faster than normal. No moisturizer clears one alone.
  • "It is caused by poor hygiene." Washing has nothing to do with it. Psoriasis appears on scrupulously clean skin, and over-washing dries and worsens the plaques.
  • "The right diet will cure it." No diet or supplement cures psoriasis. What is supported is narrower — if you carry extra weight, losing some helps, and so does cutting back on alcohol. Gluten-free eating only helps the small group who also have celiac disease. Be wary of elimination diets sold as cures.
  • "Biologics destroy your immune system." They do not suppress the immune system broadly the way older drugs did. They block one specific signal, which is why they work so well. There is a real but modest increase in some infections; tuberculosis and hepatitis screening comes first, and monitoring continues. Worth discussing rather than dismissing.
  • "If my skin is clear, my psoriasis is gone." Clear skin means the treatment is working, not that it has resolved. Most plaques return within weeks to months of stopping, and inflammation elsewhere, joints in particular, still matters.

Questions Patients Ask

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Is psoriasis curable?

No, but that is less discouraging than it used to be. It is lifelong and comes and goes, and nothing removes it permanently. What has changed is control — with modern treatment, a large share of people with moderate to severe psoriasis reach clear or nearly clear skin and keep it there for years.

Is it contagious?

Not at all. You cannot pass psoriasis to anyone by touch, by sharing a towel or a bed, or in a pool. It is your own immune system acting on your skin. The misunderstanding is often harder to live with than the plaques.

Will I get psoriatic arthritis?

Around one in three people with psoriasis does, usually years after the skin is affected, occasionally before. There is no way to predict it, so know the symptoms — joint pain and swelling, a whole finger or toe swelling up, heel or lower back pain, and morning stiffness over thirty minutes. Report those early; joint damage cannot be undone.

Are biologics safe?

Well studied and, for most people, well tolerated. They block one specific immune signal rather than suppressing the immune system broadly, which is why they work so well. There is a real but modest increase in some infections. Tuberculosis and hepatitis screening comes first, and monitoring continues. Decide from a conversation about your own risks, not a general verdict.

Does diet matter?

Less than the internet suggests, more than not at all. What has decent support is losing weight if you carry extra — that improves psoriasis on its own and makes some treatments work better — and cutting back on alcohol. Gluten-free eating helps only the small group with celiac disease too. No diet clears psoriasis.

Can I stop treatment when my skin is clear?

Usually not, and this is the commonest reason people end up back where they started. Clear skin means the treatment is doing its job, and most plaques return within weeks to months of stopping. Treatment can often be stepped down instead — a decision for your dermatologist, not you alone.

References

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