Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes Tecfidera (Dimethyl-fumarate). If you are concerned about side effects, discuss the risks and benefits of Tecfidera (Dimethyl-fumarate) with your doctor.

The following side effects have been reported by at least 1% of people taking Tecfidera (Dimethyl-fumarate). Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• Diarrhea
• flushing (e.g., becoming red in the face or body, feeling warm or hot, itchiness or burning sensation)
• heartburn
• nausea
• stomach pain or cramps
• vomiting

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• signs of infection (including Fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, or unexplained weight loss)
• signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
• signs of protein in the urine (e.g., swelling of the face or legs)

Stop taking the medication and seek immediate medical attention if any of the following occur:

• signs of a serious allergic reaction (e.g., difficulty breathing; rash; or swelling of the face, lips, tongue, or throat)
• symptoms of progressive multifocal leukoencephalopathy (PML) (e.g., seizures, vision loss, trouble thinking clearly, difficulty walking)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking Tecfidera (Dimethyl-fumarate).

120 mg
Each delayed-release capsule with a green cap and white body, printed with "BG-12 120 mg" in black ink, is filled with enteric-coated microtablets containing 120 mg of dimethyl fumarate. Nonmedicinal ingredients: colloidal silicon dioxide, croscarmellose sodium, magnesium stearate, methacrylic acid copolymer (type A), methacrylic acid copolymer dispersion, microcrystalline cellulose, polysorbate 80, simethicone, sodium lauryl sulfate, talc, and triethyl citrate. The capsule shell contains black iron oxide, FD&C Blue 1, gelatin, titanium dioxide, and yellow iron oxide.

240 mg
Each delayed-release capsule with a green cap and white body, printed with "BG-12 240 mg" in black ink, is filled with enteric-coated microtablets containing 240 mg of dimethyl fumarate. Nonmedicinal ingredients: colloidal silicon dioxide, croscarmellose sodium, magnesium stearate, methacrylic acid copolymer (type A), methacrylic acid copolymer dispersion, polysorbate 80, silicified microcrystalline cellulose, simethicone, sodium lauryl sulfate, talc, and triethyl citrate. The capsule shell contains black iron oxide, FD&C Blue 1, gelatin, titanium dioxide, and yellow iron oxide.

Do not take Tecfidera (Dimethyl-fumarate) if you are allergic to dimethyl fumarate or any ingredients of the medication.

There may be an interaction between dimethyl fumarate and any of the following:

• aminoglycoside antibiotics (e.g., gentamicin, tobramycin)
• anti-cancer medications (e.g., Mitoxantrone)
• Cyclosporine
• diuretics (water pills; e.g., Furosemide, Hydrochlorothiazide)
• fumaric acid
• lithium
• live vaccines (e.g., yellow fever vaccine, Chickenpox vaccine)
• mitoxantrone
• Mycophenolate Mofetil
• non-steroidal anti-inflammatory medications (NSAIDs; e.g., Ibuprofen, Ketorolac, Naproxen)
• other medications for MS (e.g., Fingolimod, Natalizumab)

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with Tecfidera (Dimethyl-fumarate). Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the Nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or Allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use Tecfidera (Dimethyl-fumarate).

Infection: Dimethyl fumarate can reduce the number of cells that fight infection in the body (white blood cells). If you are taking medications or have an illness that reduces your body's ability to fight infection, discuss with your doctor how Tecfidera (Dimethyl-fumarate) may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Tecfidera (Dimethyl-fumarate), and whether any special monitoring is needed.

Tell your doctor immediately if you notice signs of an infection, such as fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, or unexplained weight loss. Your doctor will do blood tests regularly to monitor your white blood cell count.

Kidney function: Treatment with dimethyl fumarate may cause an increase in the amount of protein removed from the body by the kidneys. In some cases, this may indicate a decrease in kidney function. If you have reduced kidney function or Kidney Disease, discuss with your doctor how Tecfidera (Dimethyl-fumarate) may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Tecfidera (Dimethyl-fumarate), and whether any special monitoring is needed.

Your doctor may want to test your kidney function regularly while you are taking Tecfidera (Dimethyl-fumarate).

Tell your doctor immediately if you experience symptoms of protein in the urine, such as swelling of the face or legs.

Liver function: Treatment with dimethyl fumarate may cause an increase in liver enzymes, which are chemicals produced by the liver. In some cases, increased liver enzymes can indicate a decrease in liver function. If you have liver problems, discuss with your doctor how Tecfidera (Dimethyl-fumarate) may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Tecfidera (Dimethyl-fumarate), and whether any special monitoring is needed. Your doctor may want to test your liver function regularly with blood tests while you are taking Tecfidera (Dimethyl-fumarate).

Tell your doctor immediately if you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin.

Progressive multifocal leukoencephalopathy (PML): There have been reports of PML after using dimethyl fumarate. PML is a rare disorder that causes nerve damage in the brain and is more likely to occur in people who have a weakened immune system. If you experience memory loss, vision loss, trouble thinking, or difficulty walking, contact your doctor immediately.

Vaccines: Live attenuated vaccines such as yellow fever, BCG, Cholera, typhoid, varicella, meningococcal, and diphtheria should not be given while you are taking dimethyl fumarate.

Pregnancy: Tecfidera (Dimethyl-fumarate) should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking Tecfidera (Dimethyl-fumarate), tell your doctor immediately.

Breast-feeding: It is not known if dimethyl fumarate passes into breast milk. If you are a breast-feeding mother and are taking Tecfidera (Dimethyl-fumarate), it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using Tecfidera (Dimethyl-fumarate) have not been established for children below the age of 18.

Seniors: Seniors are more likely to have medical conditions that may be affected by dimethyl fumarate. If you are a senior and taking Tecfidera (Dimethyl-fumarate), your doctor should closely monitor your medical conditions while you are taking Tecfidera (Dimethyl-fumarate).