10 Things Parents Should Know About Methotrexate 

Methotrexate isn’t new – it’s been used for more than two decades to treat juvenile idiopathic arthritis (JIA). Studies consistently show it’s safe and effective, and it’s the most commonly prescribed DMARD for JIA.  

If your child has trouble swallowing pills or recoils at the sight of needles, methotrexate is available as a drinkable liquid. Studies comparing the effectiveness of the two forms (oral and injectable) are mixed, but some doctors prefer injections because they believe the drug is better absorbed that way. When taken orally, absorption may vary due to several factors, including how much food is in your child’s stomach. Doctors may also prescribe injectable methotrexate if the oral form causes gastrointestinal problems.

For many kids with arthritis, methotrexate alone is enough to control disease activity. But if the drug isn’t working as well as hoped, your child’s doctor may do one of two things: Add another traditional DMARD (i.e., sulfasalazine or hydroxychloroquine) or a biologic (i.e., etanercept or adalimumab) to target all possible causes.

Methotrexate interferes with the body’s ability to use folate, an essential B vitamin. This may lead to folate deficiency, which can cause diarrhea, loss of appetite, mouth sores and/or mild hair shedding. Fortunately, many side effects can be prevented by taking a folic acid or folinic acid supplement (Leucovorin).

Nausea is a common side effect of methotrexate but taking it with food or milk won’t help. That’s because methotrexate-related nausea isn’t caused by stomach irritation. If methotrexate makes your child sick, your child’s doctor may prescribe ondansetron (Zofran), a drug that blocks the signal in the brain that causes nausea and vomiting.

Mixing alcohol with methotrexate increases the risk of liver damage, and the drug may also cause birth defects in children of both men and women taking the drug. If you suspect your child is drinking or is sexually active, speak with your child’s pediatric rheumatologist right away.

Methotrexate is slow acting. It could take a few weeks before your child receives any benefit and up to 12 weeks to notice any significant improvement. While waiting for the drug to take effect, your child’s doctor may prescribe other medications – including a nonsteroidal anti-inflammatory drug (NSAID) or possibly a corticosteroid such as prednisone – to ease inflammation. If after a few months your child’s symptoms still haven’t improved, your doctor may consider another treatment strategy.

Though rare, methotrexate still carries the risk of serious side effects like organ toxicity (especially liver toxicity) and low blood cell counts. Your child’s doctor will run regular blood tests to monitor the effects of methotrexate so he or she can adjust the dose or discontinue the drug if necessary.

While on methotrexate, your child should not be given any live virus vaccines (i.e., chicken pox, MMR, nasal flu vaccines), as these may increase his or her risk of infection. Most all other vaccines are safe. Before scheduling any vaccination for your child, be sure to discuss it with his or her doctor.

Even if your doctor recommends a biologic at diagnosis, your child may have to try methotrexate first before your insurer covers the cost of a more expensive drug.  This is called “Step Therapy” or “Fail First Protocols,” and the Arthritis Foundation is working hard to reform this practice across the country.