Dimethyl fumarate is used to treat relapsing forms of multiple sclerosis in adults (including clinically isolated syndrome, relapsing-remitting disease, and active secondary progressive disease).

Dimethyl fumarate may also be used for purposes not listed in this medication guide.

Dimethyl fumarate may cause a serious brain infection that can lead to disability or death. Call your doctor right away if you have problems with speech, thought, vision, or muscle movement. These symptoms may start gradually and get worse quickly.

Your doctor will perform blood tests to make sure you do not have conditions that would prevent you from safely using dimethyl fumarate.

Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose. Use the medicine exactly as directed.

You may take dimethyl fumarate with or without food. Taking the medicine with food may help prevent flushing (sudden warmth, redness, or tingly feeling).

Swallow the capsule whole and do not crush, chew, break, or open it.

While using dimethyl fumarate, you will need frequent blood tests.

Store this medicine in the original container at room temperature, away from moisture, heat, and light.

Usual Adult Dose for Multiple Sclerosis:

Initial dose: 120 mg orally twice a day for 7 days
Maintenance dose: 240 mg orally twice a day

Use: For the treatment of relapsing forms of multiple sclerosis, to include clinically isolated syndrome, relapsing-remitting disease, and active secondary progressive disease

You should not use dimethyl fumarate if you have had a severe allergic reaction to dimethyl fumarate or diroximel fumarate (Vumerity).

Tell your doctor if you have ever had:

• an active infection; or

• low white blood cell (WBC) counts.

Tell your doctor if you are pregnant or breastfeeding.

If you are pregnant, your name may be listed on a pregnancy registry to track the effects of dimethyl fumarate on the baby.

Dimethyl fumarate is not approved for use by anyone younger than 18 years old.

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Follow your doctor's instructions about any restrictions on food, beverages, or activity.

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Dimethyl fumarate may cause a serious brain infection that can lead to disability or death. Call your doctor right away if you have problems with speech, thought, vision, or muscle movement. These symptoms may start gradually and get worse quickly.

Also call your doctor at once if you have:

• symptoms of herpes virus--flu-like symptoms, cold sores around your mouth, tingly or painful blistering rash, burning pain in your thigh or lower back;

• low white blood cell counts--fever, mouth sores, skin sores, sore throat, cough, trouble breathing; or

• liver problems--loss of appetite, stomach pain (upper right side), tiredness, itching, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).

Common side effects of dimethyl fumarate may include:

• stomach pain, indigestion, nausea, vomiting, diarrhea;

• redness, rash, itching; or

• flushing (sudden warmth, redness, or tingly feeling).

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Other drugs may affect dimethyl fumarate, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.