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Methotrexate (Rheumatrex, Trexall, Otrexup, Rasuvo) is one of the most effective and commonly used medicines in the treatment of several forms of arthritis and other rheumatic conditions. It is known as a disease-modifying anti-rheumatic drug (DMARD), because it not only decreases the pain and swelling of arthritis, but it also can decrease damage to joints and long-term disability.
Methotrexate is a disease-modifying anti-rheumatic drug (DMARD) that has been used for decades to treat psoriasis and some cancers. It is used to treat rheumatoid arthritis and other forms of inflammatory arthritis and also may be used to treat lupus, inflammatory myositis, vasculitis, and some forms of childhood arthritis. It is often used in combination with other medications to treat arthritis.
Methotrexate blocks several enzymes involved in the immune system. This affects actively growing cells such as those that are in the skin, blood, gastrointestinal tissues (i.e., stomach and intestines), and the immune system. However, it is not entirely clear how methotrexate decreases the severity of arthritis.
Methotrexate typically comes in 2.5 milligram (mg) tablets. Adults with rheumatoid arthritis usually begin with a starting dose of 7.5 to 10 mg, or 3-4 pills, taken all together once a week. The dose may be increased to 20 to 25 mg a week over time if needed.
The medication also can be given as a liquid or as an injection. This comes as 25 mg per 1 milliliter (mL) and is injected under the skin, like insulin, to reduce side effects and when higher doses are needed. It is also available as a single dose auto-injector pen (Rasuvo or Otrexup) in several different doses. Adults with other rheumatic conditions may take similar doses. In children with juvenile arthritis, the dose is based on the patient's weight. Because methotrexate can affect the immune system or cause birth defects in women, it should be handled by caregivers with gloves.
If you miss a dose, you can generally take it up to 4-5 days later. If you do not realize that you missed a dose until the next dose is scheduled, talk to your doctor about what to do.
Improvements in arthritis and other conditions usually are first seen in 3-6 weeks. The full benefit of this drug may not be seen until after 12 weeks of treatment.
The most common side effects of methotrexate include nausea or vomiting and abnormalities in liver function tests. Liver function tests are blood tests your doctor may order to watch your liver. These side effects are more likely to occur at higher doses. About 1-3 percent of patients develop mouth sores (called stomatitis), rash, diarrhea, and abnormalities in blood counts. Methotrexate may cause cirrhosis (scarring) of the liver, but this side effect is rare and most likely to occur in patients who already have liver problems or are taking other drugs that are toxic to the liver.
Lung problems (persistent cough or unexplained shortness of breath) can occur rarely when taking methotrexate. These side effects are more common in people with poor lung function. Persistent cough or shortness of breath should be reported to your doctor.
Slow hair loss is seen in some patients, but hair grows back when the person stops taking this medication. This can often be managed by taking a folic acid vitamin with methotrexate. Methotrexate can increase the sensitivity of the skin to sunlight, so limiting sun exposure and the use of sunscreen is advised.
The use of folate supplements (folic and folinic acid) often are given with methotrexate. These are B vitamins and can decrease most side effects during methotrexate treatment.
It is important to remember that most patients do not experience side effects, and that, for those who do, many of the minor side effects will improve with time. Methotrexate treatment should be discontinued for at least three months before attempting to become pregnant. Even though methotrexate should not be taken during pregnancy, it does not reduce a woman’s chance of becoming pregnant in the future. Men taking methotrexate should talk to their physician prior to attempts to conceive.
Be sure to tell your doctor about all of the medications you are taking, including over-the-counter drugs and natural remedies, as some of these could increase the risk of methotrexate toxicity. Trimethoprim (Bactrim or Septra), an antibiotic often used for respiratory and urinary infections, may significantly increase the toxicity of methotrexate. The level of methotrexate can be affected by nonsteroidal anti-inflammatory drugs (NSAIDs), although these often are prescribed together for the management of rheumatoid arthritis. Other drugs that can affect the liver may increase the risk of liver damage from methotrexate. Radiation therapy, used to treat some cancers, may increase the risk of serious side effects from methotrexate as well.
Be sure to tell your other physicians that you are taking this drug. It is especially important that women discuss the use of this medicine (even past use) with their obstetrician/gynecologist. Methotrexate can cause serious birth defects and complication during pregnancy, so women taking this medication should discuss appropriate forms of birth control with their primary care physician or gynecologist. An effective form of contraception is critical while taking methotrexate and for at least three months after stopping the medication. Additionally, methotrexate can pass into breast milk, so breast feeding should be avoided while taking methotrexate.
Because this medication can lower your immunity, it is important that you discuss this with any physician treating you for an infection, as this may lead to a different evaluation or treatment. You should also talk to your doctor about whether you should stop using methotrexate if you are about to have surgery. When methotrexate treatment is discontinued, its beneficial effects on arthritis symptoms gradually disappear over a period of 2-8 weeks.
Additionally, you should discuss methotrexate with your rheumatologist before starting any chemotherapy or radiation therapy. The risk of liver injury may be increased if methotrexate is combined with other medications. Be sure to discuss this with other physicians when new medications are prescribed.
Updated March 2015 by Michael Cannon, MD, and reviewed by the American College of Rheumatology Communications and Marketing Committee. This patient fact sheet is provided for general education only. Individuals should consult a qualified health care provider for professional medical advice, diagnosis and treatment of a medical or health condition.
© 2015 American College of Rheumatology