If you have multiple sclerosis (MS), your doctor might suggest Tecfidera* as a treatment option for you. Along with other questions you may have about the drug, you could be wondering about its side effects.

Tecfidera is a prescription medication that’s used to treat the following conditions in adults:

Tecfidera comes as a capsule that you swallow. It’s typically used for the long-term treatment of MS. For more information about Tecfidera, see this in-depth article on the drug.

Like other drugs, Tecfidera can cause mild or serious side effects. Keep reading to learn more.

* Dimethyl fumarate is the generic name for Tecfidera.

Some people may experience mild or serious side effects during their Tecfidera treatment. Examples of Tecfidera’s more commonly reported side effects may include:

* To learn more about this side effect, see the “Side effects explained” section above.

Keep reading to learn about other mild and serious side effects that may happen with Tecfidera.

Examples of mild side effects that have been reported with Tecfidera include:

* To learn more about this side effect, see the “Side effects explained” section above.

In most cases, these side effects should be temporary. And some may be easily managed, too. But if you have any symptoms that are ongoing or that bother you, talk with your doctor or pharmacist. And don’t stop using Tecfidera unless your doctor recommends it.

Tecfidera may cause mild side effects other than the ones listed above. See the Tecfidera prescribing information for details.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks side effects of the medication. If you’d like to notify the FDA about a side effect you’ve had with Tecfidera, visit MedWatch.

Serious side effects of Tecfidera are rare, but they can still happen.

Serious side effects that have been reported with Tecfidera include:

* To learn more about this side effect, see the “Side effects explained” section above.
† An allergic reaction is possible after using Tecfidera. But it’s not clear whether this side effect occurred in studies.

If you develop serious side effects while taking Tecfidera, call your doctor right away. If the side effects seem life threatening or if you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Here are answers to a few frequently asked questions about Tecfidera’s side effects.

Does Tecfidera cause weight gain?

Weight gain wasn’t a side effect reported in studies of Tecfidera. But weight changes can be a symptom of multiple sclerosis (MS), which Tecfidera treats.

Other drugs used to treat MS are known to have weight gain as a side effect. For example, corticosteroids may cause weight gain. Rayos (prednisone) is an example of a corticosteroid used to treat MS.

If you’re concerned about weight gain while using Tecfidera, talk with your doctor. They can suggest ways to reach or maintain a suitable weight.

Can Tecfidera affect my teeth?

It isn’t likely. Tooth-related side effects weren’t reported in studies of Tecfidera.

MS, which Tecfidera is used to treat, may cause tooth-related problems. This is because the symptoms of this condition can make it difficult to care for your teeth.

For example, MS can cause tingling or numbness in your hands. These symptoms can make it hard to floss or brush your teeth regularly. And this can lead to problems such as tooth cavities.

Other medications used to treat MS are known to have tooth-related side effects. Examples include Aubagio (teriflunomide) and Avonex (interferon beta-1a). These medications can cause side effects such as toothache and gum disease.

Talk with your doctor about ways to lower your risk of tooth-related problems with Tecfidera and MS.

Does the generic version of Tecfidera have any side effects that differ from the brand-name drug?

No. The generic version of Tecfidera is expected to have the same side effects as brand-name Tecfidera.

Tecfidera contains the active drug dimethyl fumarate. The drug is also available in a generic form called dimethyl fumarate. Because both forms of the drug contain the same active ingredient, their side effects are typically the same.

If you have questions about what to expect with brand-name Tecfidera or its generic, talk with your doctor.

Is hair loss possible with Tecfidera?

Yes, it’s possible. Hair loss wasn’t reported as a side effect in studies of Tecfidera. But there has been at least one report of hair loss since the drug became available for use.

If you have questions about your risk of hair loss while taking Tecfidera, talk with your doctor.

Could I have withdrawal symptoms if I stop taking Tecfidera?

It’s not likely. Withdrawal symptoms are side effects that can happen if you stop taking a drug suddenly. But withdrawal side effects weren’t reported in studies of Tecfidera.

However, if you stop taking Tecfidera, it’s possible that your MS may flare up. This means you may have new or worsening symptoms of MS.

Even though withdrawal side effects aren’t likely, talk with your doctor before you stop taking Tecfidera.

Learn more about some of the side effects Tecfidera may cause.

Flushing

Flushing is the most common side effect of Tecfidera.

With flushing, you may have itching, warmth, or a burning sensation on your face or neck. Flushing caused by Tecfidera usually goes away with time.

What might help

If you have flushing while taking Tecfidera, these tips may help ease this side effect:

  • Take Tecfidera with food. In this case, you’ll take Tecfidera after you’ve eaten.
  • Take uncoated aspirin at least 30 minutes before you take Tecfidera.

If this side effect is bothersome for you, talk with your doctor. They can recommend other ways to reduce your flushing.

Belly pain (sometimes called stomach pain)

Belly pain is a common side effect of Tecfidera. It mostly occurs right after taking the drug for the first time. This side effect should go away as your body gets used to the drug.

Belly pain can also be a symptom of other side effects from Tecfidera. These include problems with digestion, such as:

What might help

Tell your doctor if you have bothersome belly pain while taking Tecfidera. They can suggest ways to ease this side effect.

Progressive multifocal leukoencephalopathy (PML)

Progressive multifocal leukoencephalopathy (PML) is a rare but serious side effect of Tecfidera.

PML is a viral condition. It happens when a certain virus attacks the central nervous system (CNS). PML causes symptoms such as:

What might help

Tell your doctor right away if you have symptoms of PML. They’ll run tests to see if you have this condition. If you test positive for PML, your doctor will likely recommend that you stop taking Tecfidera. And they’ll advise on other treatments you may need for the symptoms of this condition.

Allergic reaction

Like most drugs, Tecfidera can cause an allergic reaction in some people. But it’s not clear whether this side effect occurred in studies.

Symptoms can be mild or serious and can include:

  • skin rash
  • itchiness
  • flushing (temporary warmth, redness, or deepening of skin color)
  • swelling under your skin, typically in your eyelids, lips, hands, or feet
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What might help

If you have mild symptoms of an allergic reaction, such as a mild rash, call your doctor right away. To help manage symptoms, they may suggest an over-the-counter antihistamine you take by mouth, such as Benadryl (diphenhydramine). Or they may recommend a topical product, such as hydrocortisone cream.

If your doctor confirms you had a mild allergic reaction to Tecfidera, they’ll decide if you should continue using it.

If you have symptoms of a severe allergic reaction, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms could be life threatening and require immediate medical care.

If your doctor confirms you had a serious allergic reaction to Tecfidera, they may have you switch to a different treatment.

Keeping track of side effects

During your Tecfidera treatment, consider keeping notes on any side effects you’re having. Then, you can share this information with your doctor. This is especially helpful to do when you first start taking new drugs or using a combination of treatments.

Your side effect notes can include things such as:

  • what dose of drug you were taking when you had the side effect
  • how soon after starting that dose you had the side effect
  • what your symptoms were from the side effect
  • how it affected your daily activities
  • what other medications you were also taking
  • any other information you feel is important

Keeping notes and sharing them with your doctor will help your doctor learn more about how Tecfidera affects you. And your doctor can use this information to adjust your treatment plan if needed.

Tecfidera may not be right for you if you have certain medical conditions or other factors that affect your health. Talk with your doctor about your health history before you take Tecfidera. The list below includes factors to consider.

Weakened immune system. If you have a weakened immune system, tell your doctor before starting Tecfidera treatment. This is because Tecfidera may cause a low level of lymphocytes (a type of white blood cell). And this can raise your risk of serious infections, such as shingles. Your risk of this side effect may be even higher if your immune system doesn’t work as well as it should. Your doctor can discuss with you whether it’s safe for you to take Tecfidera.

Allergic reaction. If you’ve had an allergic reaction to Tecfidera or any of its ingredients, your doctor likely won’t prescribe Tecfidera. Ask your doctor what other medications are better options for you.

Alcohol use and Tecfidera

There aren’t any known safety issues with drinking alcohol while taking Tecfidera.

However, drinking alcohol may worsen certain side effects of Tecfidera. These include:

* To learn more about this side effect, see the “Side effects explained” section above.

If you drink alcohol, talk with your doctor about the amount that’s safe for you to drink while taking Tecfidera.

Pregnancy and breastfeeding while taking Tecfidera

Below are details about Tecfidera and pregnancy and breastfeeding.

Tecfidera and pregnancy

It may not be safe to take Tecfidera while pregnant. If you become pregnant while taking Tecfidera, tell your doctor right away.

Talk with your doctor if you plan to become pregnant while taking Tecfidera. They may prescribe a drug other than Tecfidera to treat your condition.

If you become pregnant while taking Tecfidera, consider taking part in a pregnancy registry. A pregnancy registry helps researchers understand how certain drugs can affect pregnancy. To learn more, call 866-810-1462 or talk with your doctor.

Tecfidera and breastfeeding

It isn’t known if Tecfidera is safe to use while breastfeeding.

If you’re breastfeeding or planning to breastfeed while taking Tecfidera, talk with your doctor. They can discuss with you the risks and benefits of using the drug.

Tecfidera is used to treat multiple sclerosis (MS). Some people have mild side effects, such as itching or skin rash, from Tecfidera. But serious side effects from Tecfidera, including progressive multifocal leukoencephalopathy (PML), are possible.

If you have questions about Tecfidera’s side effects, talk with your doctor or pharmacist. To help decide if Tecfidera is right for you, there are a few things you may want to discuss with your doctor. Below are a few questions you might ask:

  • Can Tecfidera cause any long-term side effects?
  • Is fatigue a possible side effect of Tecfidera?
  • Am I at higher risk of any side effects of Tecfidera?

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Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.