Methotrexate

Possible food and drug interactions when taking Methotrexate

If you are being given methotrexate for the treatment of cancer or psoriasis, you should not take aspirin or other nonsteroidal painkillers such as Advil or Naprosyn; this combination could increase the toxic effects of methotrexate. If you are taking methotrexate for rheumatoid arthritis, you may be able to continue taking aspirin or a nonsteroidal painkiller, but your doctor should monitor you carefully.

Other drugs that may increase the toxic effects of methotrexate include:

Cisplatin (Platinol)
Penicillins
Phenylbutazone
Phenytoin (Dilantin)
Probenecid
Retinoid drugs such as Retin-A and Renova
Sulfa drugs such as Bactrim and Gantrisin

Sulfa drugs may increase methotrexate's toxic effect on the bone marrow, where new blood cells are made.

Certain antibiotics, including tetracycline (Sumycin) and chloramphenicol (Chloromycetin), may reduce the effectiveness of methotrexate. This is also true of vitamin preparations that contain folic acid.

In addition, methotrexate can alter the effect of theophylline (Quibron, Theo-Dur).

Special information if you are pregnant or breastfeeding

A woman should not start methotrexate therapy until the doctor is sure she is not pregnant. Because methotrexate causes birth defects and miscarriages, it must not be taken during pregnancy by women with psoriasis or rheumatoid arthritis. It should be taken by women being treated for cancer only if the potential benefit outweighs the risk to the developing baby. In fact, a couple should avoid pregnancy if either the man or the woman is taking methotrexate. After the end of methotrexate treatment, a man should wait at least 3 months, and a woman should wait for the completion of at least one menstrual cycle, before attempting to conceive a child.

Methotrexate should not be taken by a woman who is breastfeeding; it does pass into breast milk and may harm a nursing baby.

Recommended dosage

Treatment with methotrexate is highly individualized. Your doctor will carefully tailor your dosage of methotrexate in order to avoid serious side effects and possible under- or overdosing.