What is methotrexate?

Methotrexate is a medicine that makes your immune system less active. It is used to treat certain types of cancer. It is also used to treat severe rheumatoid arthritis and psoriasis when other treatments don’t help. Rheumatoid arthritis and psoriasis are autoimmune diseases, which means that they are associated with an immune system that is too active. In some cases, methotrexate can help people who have these problems. But because it can cause some very serious side effects, it must be used carefully.

How do I take methotrexate?

Methotrexate is usually taken by mouth as a tablet. Sometimes it is given as an injection (a shot). It is a strong medicine, so it is important to take it exactly as your doctor tells you to. NEVER change the amount you take or the time of day you take this medicine. If you forget a dose, talk to your doctor before you take another dose. If you take too much methotrexate, it can cause serious side effects.

What are the most common side effects of methotrexate?

Some common side effects are loss of appetite, nausea (and sometimes vomiting), thinning hair and mouth sores. Be sure to tell your doctor about any side effects you are having.

Call your doctor right away if you:

  • Have a fever or feel as if you have the flu.
  • Have diarrhea.
  • Have a nagging cough.
  • Feel short of breath.
  • Have any unusual bruising or bleeding (e.g., black, tarry stools).

What else should I remember about taking methotrexate?

It's important to keep every appointment with your doctor. Your doctor will need to watch the medicine's effect on your body. Your doctor will also order blood tests to check your kidneys, liver and blood production.

Don't drink any alcohol, not even beer or wine. Drinking alcohol while you're taking methotrexate can cause serious liver problems.

Don't take medicine for pain or inflammation unless your doctor tells you it's okay. Pain medicines can increase the effects of methotrexate, which can be bad for you.

Don't get any vaccines (shots) while you are taking methotrexate. If you have stopped taking methotrexate, talk to your doctor to make sure that it's okay to get a vaccine.

Taking methotrexate can make it easier for you to get an infection, so try to avoid people who are sick.

Can I take methotrexate if I want to get pregnant or if I am breastfeeding?

No. Do not take methotrexate if you are pregnant, trying to get pregnant or breastfeeding. Methotrexate can hurt your baby.

You must not get pregnant while taking methotrexate. You must either use birth control (such as birth control pills, or a condom plus a spermicidal foam) or not have sex. If your doctor tells you to stop taking methotrexate, you must continue to use birth control or not have sex until you have had at least 1 menstrual period since your last dose.

I am a man, and I want to get my partner pregnant. Can I take methotrexate?

No. Methotrexate goes into your sperm. You must either use birth control or not have sex. You must continue to use birth control or not have sex for 3 months after your last dose of methotrexate.


A Family Physician's Guide to Monitoring Methotrexate by KW Jones, Pharm. D., SR Patel, M.D. (American Family Physician October 01, 2000,

Written by editorial staff

Reviewed/Updated: 05/14
Created: 10/00