Methotrexate
An old, inexpensive tablet or injection for severe psoriasis and psoriatic arthritis. It is taken once a week, not daily, and it needs regular blood tests.
Key facts
Methotrexate at a glance.
Used for
Severe psoriasis or psoriatic arthritis
Results
4–12 weeks
Treatment commitment
Weekly, with regular monitoring
Key precautions
Weekly, never daily; pregnancy precautions
What is it?
Top things to know about Methotrexate
- It modifies the immune system. Methotrexate changes immune and inflammatory activity.
- It treats severe psoriasis. It is also used off-label for other skin diseases under specialist care.
- Dosing is specific. The low-dose regimen differs from cancer treatment.
- Errors can be dangerous. Kidney function, illness and interacting medicines affect safety.
Often used for
What Methotrexate is used for
Psoriasis
Clears moderate to severe plaques.
Psoriatic Arthritis
Reduces joint symptoms.
Eczema
An option for severe eczema.
Alopecia Areata
Mixed results in small studies.
Acne
No role in acne.
HOW IT WORKS
How Methotrexate works
Diagram explanation and sources
Interferes with cell replication: Blocks folate-dependent processes used to make DNA. May increase adenosine signaling: This calming messenger can limit immune-cell activity. Reduces skin inflammation: Inflammatory activity and plaque buildup can decrease.
The psoriasis mechanism is not fully established. Folate antagonism affects replication, while low-dose anti-inflammatory actions include proposed adenosine pathways supported by experimental work; their precise clinical contributions are unresolved.
Brands
Brands of Methotrexate
Brand names and available preparations vary by country. The examples below identify specific labeled products.
Trexall
An oral brand containing methotrexate.
Rasuvo
An injectable brand containing methotrexate.
Otrexup
An injectable brand containing methotrexate.
Strengths
Methotrexate strengths
Methotrexate for psoriasis is taken once weekly, not daily. The cited tablet label describes 10–25 mg per week, adjusted by the prescriber, with a 30 mg/week ceiling. Tablet strength and weekly dose are different: multiple 2.5 mg tablets or a prescribed injection may be needed.
10–25 mg/week
30 mg/week
The total weekly amount is individualized with laboratory monitoring and folate planning. It is not a daily dose.
A prescribing ceiling, not a routine goal or a standard starting dose. Kidney function, interactions and toxicity may require substantially less.
Strength sources
Forms
Methotrexate forms
Tablet
A solid oral form. Size, coating and ease of swallowing vary by product.
Prefilled pen
An injector supplied with medication inside. Grip, activation and needle handling depend on the device.
How to use it
Your treatment, step by step.
How to take it
- 01
When to take it
Once a week, on the same day every week. Choose a day you will remember and write it somewhere visible. Some people take the whole dose at once; some split it into two portions about twelve hours apart on the same day to reduce nausea. Do not spread it across different days unless you were told to.
Take tablets with water, and with food if they upset your stomach. An evening dose means the tiredness and mild nausea happen while you are asleep.
Folic acid goes on the other days, as prescribed. It is not a substitute for a missed methotrexate dose.
With the weekly injection, keep to the same day and rotate the site. - 02
If you miss a dose
Take it as soon as you remember if it is within about two days of your usual day. If longer, skip it and take the next on your usual day. Never take two weekly doses close together to catch up, and never take a daily dose to make up for a missed week.
If you have taken more than one weekly dose, or taken it several days in a row, contact a doctor or a poison center straight away. Do not wait to see how you feel. This overdose is treatable caught early and dangerous when it is not.
Monitoring & follow-up
Methotrexate is watched by blood test, and the schedule is not optional. The problems it causes are silent until they are advanced.
Before starting: Full blood count, liver tests, kidney function, and a pregnancy test where relevant. Hepatitis B, hepatitis C, HIV and tuberculosis screening is standard, because the drug damps the immune system. A chest x-ray if there is any history of lung disease.
Early on: Blood counts and liver tests within a week or two of starting, and again after each dose increase. This is when a sudden drop in blood counts would show.
Once stable: Full blood count, liver tests and kidney function every one to three months, depending on the dose and what else you take, for as long as you are on the drug.
The liver over the long term: Years of methotrexate can scar the liver, and the risk rises with total lifetime dose, heavy alcohol use, obesity, diabetes and fatty liver disease. Biopsy used to be the check; most clinics now use a blood marker of scarring and a scan of liver stiffness.
The lungs: A rare but serious lung inflammation can occur. A new dry cough, breathlessness or fever means being seen, not waiting for the next appointment.
What to report between tests: Mouth ulcers, unexplained bruising or bleeding, sore throat or fever, dark urine, yellowing of the eyes or skin, severe nausea, any new cough or breathlessness.
What to expect
How things change over time.
Taking it
Once a week, not daily, with folic acid on the other days. Nausea, tiredness or mouth soreness in the day or two after each dose is common early on; folic acid usually blunts it.
Settling in
Nothing visible in the skin yet.
Working
Plaques thin and spread less, thickness and scale first. Joint pain from psoriatic arthritis often improves in the same window, one reason it is chosen over a skin-only treatment.
Judge it here
Substantial improvement is the realistic target.
Long term
Where it suits, the result holds while the dose continues, with regular blood tests. Some stay on it for years.
Nails
Nail psoriasis can improve, but slowly. Nails always lag behind the skin.
- First dose
- Weeks 1 to 2
- Weeks 4 to 8
- About 3 months
- Beyond 3 months
- Many months
When you stop
No taper, no physical withdrawal. It is stopped outright for serious infections, before some surgery, and whenever a pregnancy is being considered.
Psoriasis generally returns over weeks to a few months. Joint symptoms often come back faster than the skin, which catches people out.
The drug leaves the body within days, but the pregnancy advice runs far longer, for both partners, and the interval should come from your own doctor.
If it is stopped because it stopped working rather than for side effects, it is usually replaced, since severe psoriasis rarely stays quiet on its own.
What it Pairs with
Methotrexate + your routine
| Product or situation | With Methotrexate | What to know |
|---|---|---|
| Taking it more than once a week | Avoid | This is the error that has killed people. There is no daily psoriasis dose. If you have taken extra doses, get advice the same day. |
| Skipping the folic acid | Avoid | Not optional. It reduces nausea, mouth ulcers and blood count problems without reducing how well methotrexate works. |
| Missing your blood tests | Avoid | The problems this drug causes show up in blood results before you feel them. Missed tests are the main way avoidable harm happens. |
| Regular or heavy drinking | Use care | Alcohol and methotrexate both stress the liver. Most doctors ask people on it to keep alcohol low or stop, so agree an actual limit. |
| Trimethoprim antibiotics | Avoid | These block folate the same way methotrexate does, and together they can cause severe bone marrow failure. Make sure every prescriber knows you take methotrexate. |
| Starting new medicines without checking | Avoid | Over-the-counter ones count. Regular anti-inflammatory painkillers, some stomach acid drugs and several antibiotics raise methotrexate levels. Make it a decision rather than an accident. |
| Live vaccines | Avoid | Live-virus vaccines are generally avoided. Non-live vaccines, including the usual flu vaccine, are encouraged. |
| Sunbeds and burning | Avoid | Old sunburn can flare back up on methotrexate, and the drug adds to sun sensitivity. |
| Pregnancy while taking it | Avoid | Getting pregnant, or fathering a pregnancy, is covered in Ask Your Doctor, and applies to both partners. |
| If you are pregnant, might be pregnant, or are planning a pregnancy | Use care | Methotrexate must not be taken in pregnancy. It causes miscarriage and serious birth defects. The advice covers both partners, and it must be stopped well in advance — ask the doctor managing your care how long. |
| If you are breastfeeding | Use care | It passes into breast milk and is not used while breastfeeding. Ask the doctor managing your care. |
| If you have a liver problem | Use care | Liver disease, fatty liver, hepatitis B or C, and regular drinking all count. Each raises the risk of liver damage. |
| If you have kidney disease | Use care | Reduced kidney function raises levels and toxicity sharply, so the dose is lowered or another drug chosen. |
| If you take a trimethoprim antibiotic | Use care | Trimethoprim and trimethoprim-sulfamethoxazole with methotrexate can cause severe bone marrow failure, so the combination is generally avoided. |
| If you start any new medicine | Use care | Regular anti-inflammatory painkillers and stomach acid tablets count. Several common drugs raise methotrexate levels, so every prescriber should know you are on it. |
| If you develop a cough or fever | Use care | A new dry cough or breathlessness counts too. A rare lung inflammation can occur, and fever may mean an infection you cannot fight as well. |
| If you develop mouth ulcers or bruising | Use care | Unusual bleeding or yellowing of the eyes counts too. These are the blood count and liver problems the monitoring exists to catch. |
| If you are due surgery or a vaccination | Use care | Methotrexate is sometimes paused around surgery, and live vaccines are generally avoided. |
Side effects & when to get help
This is a once-a-week drug, and the once-a-week part is the most important thing on the page. Taking it daily by mistake causes serious harm. Folic acid handles most of the everyday side effects.
Common
Nausea on dosing day: Often better taken at night, or split over the day.
Tiredness for a day or two after: Sometimes called the methotrexate hangover.
Mouth sores: Folic acid usually prevents them.
Hair thinning: Mild, and it reverses.
Tell your doctor
Mouth sores that keep coming back: Your folic acid may need changing.
A new cough or shortness of breath: Get it checked rather than waiting.
Rising liver enzymes or a falling blood count: From your routine blood tests.
Any new medicine: Especially trimethoprim, some antibiotics, and regular anti-inflammatories.
How much alcohol is reasonable: Ask your doctor. It is a liver question, and the answer is personal.
Stop and get care
Fever with mouth ulcers and feeling very ill: Can mean your blood counts have dropped.
Shortness of breath with a dry cough
Black stools, or vomiting blood
Taking it more than once in a week: Call right away, even if you feel fine.
Getting it and cost
Getting Methotrexate.
Cost & access
Generic methotrexate tablets are among the least expensive systemic treatments in dermatology. Folic acid is cheap too.
What affects the cost
The weekly auto-injector pens cost considerably more, and coverage usually requires showing that tablets caused nausea or did not work well enough. Plain injectable vials are cheaper than the pens.
What affects the cost
The real cost is the monitoring, repeated blood tests and periodically a liver scan or blood marker. Usually covered, but they are appointments and not optional.
What affects the cost
Insurers frequently require a trial of methotrexate before approving a biologic, one reason it is still so often the first systemic drug tried.
Alternatives
Other options to consider.
Acitretin
an oral retinoid, not an immunosuppressant, so no infection risk and no blood count problems. It works less well alone for plaque psoriasis, dries the lips and skin badly, and cannot be used by anyone who might become pregnant for years afterwards.
Ciclosporin
works much faster than methotrexate and is used for severe flares, but it raises blood pressure and damages the kidneys over time, so it is a short-term drug rather than a years-long one.
Apremilast
a tablet with a much lighter monitoring burden and no blood tests, and better tolerated, but generally less effective for skin than methotrexate and considerably more expensive.
Biologic injections
clear skin far more completely than methotrexate and are usually better tolerated. They cost far more, and most insurers ask for methotrexate to be tried first.
Phototherapy
no systemic risk at all and good evidence for plaque psoriasis, but it means repeated visits to a clinic, and it does nothing for psoriatic arthritis.
Questions
Questions you might be asking.
How often do I take it?
Once a week, on the same day. Never daily. Daily dosing by mistake is the most dangerous error with this drug and it has been fatal. Get medical help the same day if it happens.
Why do I also have to take folic acid?
Methotrexate blocks folate, and the mouth ulcers, nausea and low blood counts come from that. Folic acid on the other days restores enough folate to reduce them without stopping the treatment working.
Do I really need all the blood tests?
Yes. Liver damage and falling blood counts cause no symptoms until they are advanced. The tests are the only early warning.
Can I drink alcohol?
The concern is regular drinking, not a single glass, because alcohol and methotrexate both stress the liver. Agree an actual limit with your doctor.
Can I take it if I want to have a baby?
No. It must be stopped well before trying to conceive, and the advice covers both partners. It causes miscarriage and serious birth defects. Ask your own doctor how far in advance.
How long before I know if it is working?
Give it about three months. First changes often show at four to eight weeks, but three months on a tolerated dose is the fair point to judge.
Is it chemotherapy?
It is chemotherapy at much higher doses. At psoriasis doses it acts as an immune-calming drug, and the experience is not comparable.
Related
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