Ingredient

Coal Tar

An old psoriasis and eczema treatment that still works. It smells, it stains, and it makes skin burn easily in the sun.
Dr. Schwarz, MD · Board-certified dermatologistLast reviewed September 8, 2026
Five medicated scalp products on white, including Amazon Basics tar gel, T+Plus, MG217, RoyceDerm and Nizoral

Start here

Coal tar works, which gets lost in how unpleasant it is to use. For scalp psoriasis, thick plaques, and stubborn dandruff it slows the skin down and calms it at once, and the effect lingers after you stop. On the cancer question, tar does contain known carcinogens, but that evidence comes from industrial workers exposed for years; studies of treated patients show no clear rise in skin cancer, which is why it is used in courses rather than for decades. Plan around the mess — old towels, dark pillowcase — and take the sun warning seriously, because tar makes skin burn easily for about a day.

— Dr. Schwarz, Board Certified Dermatologist

Key Facts

−
Also calledCrude coal tar, coal tar solution, liquor carbonis detergens, LCD, coal tar extract
TypeA complex mixture from coal. Slows overactive skin cell turnover and calms inflammation
Strengths sold0.5% to 5% over the counter in shampoos, creams and bath additives. Higher strengths through a doctor or a pharmacy that compounds
UseTwo or three times a week for the scalp. Once daily or on alternate days for the body
Time to work2 to 4 weeks for scale and itch, up to 8 weeks for thick plaques
Prescription neededNo for the usual strengths. Yes for crude coal tar preparations and for hospital regimens

What It Is

−

Coal tar is what is left when coal is heated without air — a thick, dark, strong-smelling liquid of thousands of compounds, used on skin since the 1800s. It is one of the oldest treatments in dermatology still in routine use. Because it is a mixture rather than one molecule, labels confuse people. Crude coal tar is the raw material. Coal tar solution is a diluted, purified alcoholic version. LCD, or liquor carbonis detergens, is another refined extract. A product listing 2% coal tar solution holds less actual tar than one listing 2% crude coal tar, so percentages do not compare across brands. In the United States, coal tar at 0.5% to 5% is approved over the counter for psoriasis, seborrheic dermatitis and dandruff, in shampoos, creams, ointments, foams and bath additives. Europe is stricter — the EU restricts crude coal tar in cosmetics, so there it is prescription or pharmacy-only.

How It Works

−

Psoriasis makes skin cells too fast and pushes them to the surface, where they pile up as thick scale. Coal tar slows that down, so plaques thin and scale drops over weeks rather than days.

It is also anti-inflammatory and anti-itch, with mild antibacterial and antifungal activity — the part that helps dandruff and seborrheic dermatitis. That is why one ingredient covers such different-looking conditions.

The newer finding is about eczema. Coal tar switches on the aryl hydrocarbon receptor inside skin cells, which raises production of barrier proteins including filaggrin — it helps the skin rebuild the seal eczema broke. That was only worked out in the last fifteen years, long after the treatment was in use.

What it does not do is work quickly. Nothing much happens in the first week. The effect builds over a month and tends to persist for weeks after you stop, which is unusual and part of why it is still used.

Here is where Coal Tar acts in the skin, and what the others do instead.

About Coal Tar
Compare
Skin basics
BARRIEREPIDERMISDERMIS28 days4-6 daysSLOWS SKIN CELLS DOWNCROSSES EASILYQUIETS THE IMMUNE SIGNAL

In a plaque, skin cells travel from the bottom of the epidermis to the surface in four to six days instead of a month, and pile up as scale. Coal Tar slows them back down, so the plaque thins. The oldest option, and it works. It smells and it stains.

Coal tar is a mixture of many small fat-soluble molecules, so it enters easily. The smell and the staining come with it.

The redness, swelling and itch are the immune system reacting, not the damage itself. This turns that reaction down where it is happening, in the skin, which is why a rash settles within days.

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.

What It Treats

−
Scalp Psoriasis

Scalp Psoriasis

Strong evidence

The most useful thing on the shelf for scalp psoriasis. It slows the overactive cell turnover and takes down scale and itch, which no other over-the-counter option does. Apply it to the parted scalp rather than the hair, leave it five to ten minutes, and expect a smell and possible staining of light hair and towels.

Psoriasis

Psoriasis

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.

Dandruff

Dandruff

Moderate evidence

Works by slowing the shedding rather than by treating the yeast, so it suits thick, heavy flaking more than a mildly itchy scalp. It smells strongly and it stains light hair and fabric, which is why most people use it only during a flare. It is also useful when scalp psoriasis is in the picture too.

Not the Best For

−
Seborrheic Dermatitis

Seborrheic Dermatitis

Limited evidence

An older shampoo that slows scaling and helps some people with a stubborn, thickly flaking scalp. It is more useful when psoriasis is in the picture too. It smells strong and can stain light hair, and there are gentler options with better evidence for this condition, so it is rarely where to start.

Forms

−

Coal tar is sold mainly for the scalp, and shampoo is the easiest start. On the body, ointments do the most for thick plaques, while foams and gels are more wearable on skin other people see. Bath additives suit widespread disease, children, and anyone with too much skin to cream by hand. It stains, it smells, and it makes skin burn easily. Tar plus sun is the combination to avoid.

A row of Coal Tar products sold as shampoo, photographed on white.
Scalp, and the usual start
Shampoo
For scalp psoriasis, seborrheic dermatitis and dandruff. Left on a few minutes before rinsing.
A row of Coal Tar products sold as ointment, photographed on white.
Thick plaques
Ointment
The greasiest and the most effective on the body. Stains fabric, so old clothes and old sheets.
A row of Coal Tar products sold as foam or gel, photographed on white.
Skin people can see
Foam or gel
Far more wearable than an ointment, and easier on hairy areas.
A row of Coal Tar products sold as cream or lotion, photographed on white.
Everyday body use
Cream or lotion
A middle option. Less messy than ointment, less powerful.
A row of Coal Tar products sold as bath additive, photographed on white.
Widespread skin
Bath additive
Poured into the water. Practical for children and for large areas.

Strengths

−

Percentages on tar labels mean less than they look, because the same number covers crude tar, a solution or an extract. Go up only if a lower strength has been used properly for a month and stalled.

WeakestStrongest
0.5% to 1%2% to 3%5%Crude coal tar preparations
Over the counter
0.5% to 1%
Everyday shampoos and mild creams. Maintenance and dandruff.
Over the counter
2% to 3%
The working strength for scalp psoriasis and stubborn seborrheic dermatitis.
Over the counter
5%
Strongest without a prescription. Better on thick plaques, and more drying and irritating to match.
Prescription or compounded
Crude coal tar preparations
Stronger again, kept for thick, resistant plaques, often with salicylic acid or supervised ultraviolet light.

Basics

−
When to Apply
Shampoo two or three times a week, worked into the scalp and left on five to ten minutes before rinsing. Creams and ointments once a day or every other day, usually at night, applied with the direction of hair growth to reduce folliculitis. Bath additives in a warm, not hot, bath for ten to twenty minutes.
How to Start
Two or three times a week for the first two weeks, on a small test area first. Old towels and a dark pillowcase from the start; staining is easier to prevent than remove. Wear sunscreen and keep treated skin covered for at least 24 hours after use.
If It Irritates
Mild stinging, dryness and temporary darkening are expected. Small pustules around hair follicles — tar folliculitis — mean you are using it too often or too thickly, and settle with a few days off. Burning, spreading redness or blistering means stop, and usually means sunlight reached treated skin.
If It’s Not Working
Give it four to eight weeks. Thick, stuck-down scale needs salicylic acid first to lift it, because tar cannot reach skin it cannot touch. If plaques have not thinned after two months, the next step is a prescription treatment, not stronger tar — modern psoriasis drugs beat anything over the counter.

What to Expect

−
Week 1Weeks 2 to 4Weeks 6 to 8After stopping
Adjusting
Week 1
The smell, plus stinging or dryness. Treated skin can look darker. Little change in the plaques yet.
Working
Weeks 2 to 4
Scale drops, itching settles, plaques flatten. This is when people decide it is worth the mess.
Judge it here
Weeks 6 to 8
Thick plaques take this long. Nothing thinner after two months of correct use means go prescription.
Lingering benefit
After stopping
Unusual for a topical — improvement often holds for several weeks after a course.

What to Avoid

−
  • Sunlight, fabric and open skin Most of coal tar's constraints come down to these three.
  • Sun exposure for 24 hours after use tar makes skin burn far more easily, and a burn on treated skin is the most common bad outcome. Cover up, wear sunscreen, and never pair it with a sunbed.
  • Broken, weeping or infected skin Freshly inflamed skin too. It stings sharply and is absorbed more. Wait until skin is intact.
  • Light fabrics and surfaces it stains clothing, bedding, towels, tubs, and light, gray or bleached hair. Use old dark textiles and rinse the bath immediately.
  • The face, the genitals and skin folds thinner skin, more absorption, easier irritation. Not intended for these areas unless a doctor says otherwise.
  • Applying it thickly or against the hair Both make tar folliculitis, the crop of small pustules around follicles, more likely.

If You Stop

−

Psoriasis comes back, but more slowly than with most topical treatments. The gain often holds for several weeks after the last application, which is why tar is used in courses rather than continuously. Dandruff and seborrheic dermatitis return faster, usually within two to four weeks, as the yeast driving them recolonizes the scalp. Most people end up using it once a week or alternating with an antifungal shampoo. There is no rebound flare and nothing to taper. Skin staining fades within days; stained hair may take several washes. Extra sun sensitivity settles within about a day of the last application.

Ask Your Doctor

−
If you develop pustules or boils where you are applying it: Usually settles with a break. Get it checked if it spreads.
If treated skin burns, blisters or becomes very red after sun exposure: Sun sensitivity lasts about a day, and a burn needs proper care.
If you are using it on more than a small area, or for more than a few weeks at a time: Plan long courses and large areas with a doctor.
If your psoriasis is widespread, painful, or affecting your joints: That needs systemic treatment, not a topical one.
If your skin is broken, weeping or infected: Tar waits until it has healed.
If you are pregnant or breastfeeding
Coal tar is usually avoided — ask the doctor managing your pregnancy.

How It Compares

−

Topical steroids

Different job

And much faster on an inflamed plaque. They cannot be used continuously because of skin thinning, which is why tar is often used to hold the ground between steroid courses.

Vitamin D analogs such as calcipotriol

The same

Cleaner to use, and the usual prescription first choice for plaque psoriasis. Coal tar is available without a prescription and does not have the same limits on how much can be used.

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.

Salicylic acid

Different job

It lifts scale rather than treating the process underneath, and it works well used before tar rather than instead of it.

Ketoconazole or pyrithione zinc shampoo

Different job

For dandruff and seborrheic dermatitis, and far more pleasant to use. Coal tar does more where psoriasis is the real problem.

Phototherapy16:9 hero for Narrowband UVB Phototherapy. Never cropped: the tone strip and the corner logo depend on the full frame.

Phototherapy

Better

More effective than any topical, and it requires a course of hospital or clinic appointments.

Myths

+
  • "Coal tar causes skin cancer." The answer is more specific than yes or no. Coal tar contains polycyclic aromatic hydrocarbons, recognized carcinogens, and industrial workers with heavy, prolonged exposure have had higher cancer rates. Studies of patients treated on the skin for psoriasis and eczema, with long follow-up, found no clear increase in skin cancer. Most doctors respond by using it in courses rather than continuously for decades.
  • "It is old-fashioned, so newer treatments must be better." Newer prescription treatments are more effective, true. Tar is still one of the better things available without a prescription, and its effect lasts after stopping, which most modern topicals do not.
  • "The stronger the smell, the better it works." Smell tracks how refined the preparation is, not how well it works. Refined extracts smell less and still work.
  • "The dark staining on my skin means it is damaging it." That brown stain is tar sitting on the surface. It washes off in days and is not a burn or a pigment change.
  • "If a little helps, more will help faster." Thicker and more often mainly produces irritation and tar folliculitis. Lifting the scale with salicylic acid does more for a stubborn plaque than doubling the tar.

Questions Patients Ask

+

Does coal tar cause cancer?

Tar contains known carcinogens, and heavy industrial exposure over years is linked to cancer. Studies of patients treated on the skin show no clear increase in skin cancer. Most doctors call that reassuring but not final, and use tar in courses rather than for years. If you have had skin cancer or heavy sun damage, raise it before starting.

Will it stain my hair or my clothes?

Both, plus towels, bedding and the bath. Light, gray, bleached and color-treated hair picks up a tint most easily. Rinse thoroughly, use dark towels and pillowcases, and clean the bath straight afterward.

Why do I have to stay out of the sun?

Tar makes skin much more sensitive to ultraviolet light for about 24 hours, so it burns at exposures that would normally be harmless. Cover treated skin and use sunscreen. Clinics do combine tar with measured ultraviolet light, but that is a controlled dose under supervision, not something to try at home.

How bad is the smell?

Noticeable, and it lingers on hair and skin for a few hours. Refined extracts and modern foams and gels smell much less than crude tar, so ask for one of those if the smell would make you stop.

Can I use it on my face or on my child?

Not without advice. Facial skin, skin folds and children's skin absorb more and irritate more easily, so a doctor should pick the strength and the areas.

How long can I keep using it?

Courses of a few weeks rather than indefinitely, with breaks in between or dropping to once a week for maintenance. Needing it continuously for months means the condition needs a prescription treatment, not more tar.

References

+