Dimethyl Fumarate: What It Does, Side Effects & Practical Tips

Seen the name dimethyl fumarate on a prescription and wondering what it actually does? This drug—often called DMF—is used most commonly to treat relapsing multiple sclerosis and, in some forms, psoriasis. It calms immune activity and lowers inflammation. That’s why it helps reduce relapses in MS and eases certain inflammatory skin conditions.

How to take dimethyl fumarate

The usual oral schedule starts low and steps up. For MS, many people begin with 120 mg twice daily for the first week, then move to 240 mg twice daily. Follow your doctor’s exact plan; don’t change doses on your own. Take it with food to cut down stomach upset. If you forget a dose, take it when you remember unless the next dose is close—don’t double up.

Need to stop or switch? Talk to your neurologist. Stopping suddenly can be okay in some cases, but your doctor will make the plan so your disease stays controlled and any risks are monitored.

Side effects, monitoring, and safety tips

The common side effects are flushing (warmth, redness) and mild-to-moderate stomach issues like nausea, diarrhea, or belly pain. Flushing often improves after the first month. Taking the pill with food and using aspirin for uncomfortable flushing (ask your doctor first) can help.

Less common but serious effects need checking. Dimethyl fumarate can lower white blood cells, especially lymphocytes, so clinics want a baseline complete blood count (CBC) and repeat checks—often every 3 months. Liver tests may be done too. If your white cell count drops a lot, your doctor may pause treatment.

Avoid combining DMF with other strong immune-suppressing meds unless your specialist approves. If you have an active infection, recent serious infection history, or are pregnant or planning pregnancy, discuss risks and alternatives. Pregnant people should get personalized advice—data is limited and decisions depend on individual risk.

Watch for warning signs: persistent fever, severe infections, unexplained bruising, very low white counts, or new neurologic changes. If any of these appear, contact your care team right away.

Practical tips: store the medicine at room temperature, keep a log of doses and side effects, and bring your list of meds to every visit so your doctor can check interactions. If stomach upset is the main issue, try smaller meals when you take the pill. If flushing is frequent and severe, your doctor can suggest options or dose timing changes.

Questions about cost, brands, or ordering online? Ask your clinic for trusted pharmacy options and avoid sellers without a prescription requirement. Your healthcare team can point you to patient-assistance programs if cost is a barrier.

Want specifics for your case? Bring your questions and test results to your next appointment—dimethyl fumarate works well for many people, but the best plan is the one tailored to you.