Methotrexate is an oral medication that has been prescribed since the 1970’s for the treatment of psoriasis that is unresponsive to topical psoriasis medications.
Methotrexate is prescribed most commonly to treat cancer, but was found to be effective in clearing psoriasis and was approved by the U.S. Food and Drug Administration (FDA) for the treatment of moderate to severe psoriasis.
In general, methotrexate produces a 70% improvement in at least 70% of patients being treated. Improvement is often experienced within four to six weeks of starting methotrexate.
Methotrexate slows skin cell growth by inhibiting an enzyme in the skin that is responsible for the rapid division of skin cells.
Methotrexate is indicated for adults with moderate to severe:
- plaque psoriasis
- erythrodermic psoriasis
- acute and localized pustular psoriasis
- psoriatic arthritis
- and for those people who have not responded to treatment with phototherapy, PUVA, or oral retinoids (Soriatane®).
Methotrexate: How it is Used
Methotrexate is most commonly taken orally, either in pill or liquid form. The liquid form may be mixed with fruit juice. The drug can be taken in single or divided doses, split up over a period of 24 hours.
Methotrexate may be prescribed in combination with other psoriasis treatments, such as cyclosporine and oral retinoids, such as Soriatane.
The following guidelines may be helpful when taking methotrexate.
- Take only the prescribed, correct amount of methotrexate at the SAME TIME AND DAY each week.
- Do NOT begin or change the dosage or any medication (including nonprescription medications) unless first approved by your doctor.
- Avoid drinking alcoholic beverages while taking methotrexate
- If you have side effects or any symptoms of dehydration, notify your physician before the next dose.
- If you develop cough, fever, shortness of breath or have any problems with sore throat; infections, including skin infections; or skin or mouth ulcers, stop methotrexate and call your doctor.
- See your doctor regularly, usually every 4 weeks (more frequently at the beginning of therapy)
- Do not miss your doctor’s appointment or blood tests.
- Notify your doctor immediately if you accidentally take too much of the medication.
Methotrexate: Blood Tests
People taking methotrexate should have regular blood tests to monitor its impact on the bone marrow and liver.
Methotrexate: Side Effects
The less common side effects of long-term methotrexate treatment include liver damage. The risk of liver damage increases if a person drinks alcohol, has had prior liver disease, has abnormal kidney function, is obese, or has diabetes.
In rare circumstances, the use of methotrexate can lead to the development of certain types of cancer, such as lymphoma. Methotrexate can also cause a reduced white blood cell count and increase the risk of developing serious infections.
Gerald D. Weinstein and Alice. B. Gottleib, Therapy of Moderate-to-Severe Psoriasis, 2nd Edition (New York: Marcel Dekker, Inc., 2003), p. 132.