Tecfidera (dimethyl fumarate) is a brand-name prescription medication. It’s typically used as a long-term treatment for multiple sclerosis.

Specifically, Tecfidera is approved by the Food and Drug Administration (FDA) to treat the following conditions in adults:

Here are some fast facts about Tecfidera:

  • Active ingredient: dimethyl fumarate
  • Drug class: Nrf2 activator, a type of drug called an immunomodulator
  • Drug form: oral capsule

Like other drugs, Tecfidera can cause side effects. Read on to learn about potential common, mild, and serious side effects. For a general overview of Tecfidera, including details about its uses, see this article.

Tecfidera can cause certain side effects, some of which are more common than others. These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

These are just a few of the more common side effects reported by people who took Tecfidera in clinical trials:

* For more information about this side effect, see “Side effect specifics” below.
† For more information about this side effect, see “Digestive side effects” in the “Side effect specifics” section below.

Mild side effects can occur while taking Tecfidera. This list doesn’t include all possible mild side effects of the drug. For more information, you can refer to Tecfidera’s prescribing information.

Mild side effects that have been reported with Tecfidera include:

These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks side effects of the medication. If you develop a side effect while taking Tecfidera and want to tell the FDA about it, visit MedWatch.

* For more information about this side effect, see “Side effect specifics” below.

Tecfidera may cause serious side effects. The list below may not include all possible serious side effects of the drug. For more information, you can refer to Tecfidera’s prescribing information.

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

Serious side effects that have been reported and their symptoms include:

* For more information about this side effect, see “Side effect specifics” below.
† An allergic reaction is possible after taking Tecfidera. However, it’s not clear how often this side effect occurred in clinical trials.

Long-term side effects

Tecfidera isn’t known to cause long-term side effects.

However, Tecfidera may increase your risk of infections, and some infections may cause long-term problems. For example, a shingles infection may cause lasting nerve problems. Rarely, brain infections may occur while taking Tecfidera, and some serious brain infections can lead to severe, permanent disabilities. These infections have occurred in people who have taken Tecfidera for a long time.

Tecfidera’s common side effects, such as flushing and nausea, are usually temporary. These side effects are more common when you first start the drug. These side effects usually go away within a month.

If side effects from Tecfidera become severe or don’t go away, talk with your doctor. They may suggest stopping treatment with the medication.

Tecfidera may cause several side effects. Here are some frequently asked questions about the drug’s side effects and their answers.

Are weight gain or fatigue side effects of Tecfidera?

Tecfidera shouldn’t cause weight gain or fatigue. These side effects weren’t seen in the drug’s clinical trials.

However, fatigue is a symptom of multiple sclerosis (MS). Tecfidera is prescribed to treat MS. And weight gain is common among people with MS. This is because some MS symptoms can reduce a person’s ability to exercise. Some examples of these symptoms are low energy levels, stiffness, and balance problems.

Fatigue can also be a symptom of liver damage,* a rare, potentially serious side effect Tecfidera may cause.

Talk with your doctor if you have weight gain or fatigue while taking Tecfidera. They can suggest ways to manage these symptoms.

* For more information about this side effect, see “Side effect specifics” below.

Does Tecfidera cause hair loss?

No, hair loss wasn’t a side effect reported by people who took Tecfidera in clinical trials.

In one report, a person had temporary hair loss during the first few months of taking Tecfidera for relapsing-remitting multiple sclerosis (RRMS). Their hair loss improved over a few more months of continued treatment. And it isn’t known for sure if the drug was the cause.

If you notice hair loss while taking Tecfidera, talk with your doctor. They may be able to help find what’s causing your hair loss and suggest ways to manage it.

Should I expect any side effects when stopping Tecfidera treatment?

No, stopping Tecfidera treatment shouldn’t cause side effects. However, stopping taking this medication may lead to worsened symptoms or progression of MS.

If you have questions about stopping treatment with Tecfidera, talk with your doctor. They can guide you on whether a different treatment option would be better for you.

Do Tecfidera’s side effects vary between the 120-mg and 240-mg strengths?

No, Tecfidera’s possible side effects are the same with both strengths. However, it’s important to note that only the maintenance (ongoing) dosage of Tecfidera has been shown to be effective for the drug’s approved uses. The recommended maintenance dosage is 240 milligrams (mg) twice per day. The lower strength (120 mg) is typically prescribed only as a starting dose for the first week of treatment.

Some people have digestive problems, such as nausea and diarrhea, when they start taking the maintenance dosage. In this situation, your doctor may suggest temporarily reducing your dose of Tecfidera to 120 mg. However, this lower strength is prescribed only short term for up to 4 weeks because it may not work as well for treating your condition. If digestive problems remain severe at this dose, your doctor will likely recommend switching to a different treatment option.

If you have additional questions about the side effects of different Tecfidera strengths, talk with your doctor.

Are teeth-related side effects possible with Tecfidera?

Tecfidera shouldn’t cause tooth problems. People who took the drug in clinical trials didn’t report any teeth-related side effects.

People with MS may have more dental problems than those without the condition. It’s thought that certain MS symptoms could make oral health practices more challenging. For example, some people with MS have numbness or tremors in their hands. This can make it harder to grip or maneuver a toothbrush and floss.

If you have a toothache or other tooth-related problems, talk with your dentist. They can recommend ways to fix the problem and maintain good oral hygiene.

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

Flushing

Flushing is a common side effect of Tecfidera. In fact, it was the most common side effect seen in people taking this medication in clinical trials.

Flushing occurs when the blood vessels just under your skin dilate (widen). Symptoms most commonly appear on your cheeks, neck, and chest. And these symptoms may include reddening or deepening of skin color, warmth, or a burning sensation.

Flushing from Tecfidera is usually temporary or easily managed. Less commonly, flushing can be severe.

What you can do

Symptoms of flushing tend to be worse when you first start taking the drug. Flushing usually gets better or goes away after the first month of treatment.

To help prevent or ease this side effect, it’s best to take Tecfidera with food.

Taking a non-coated aspirin tablet 30 minutes before taking Tecfidera may also help reduce or prevent flushing. The drug’s manufacturer suggests that aspirin doses of up to 325 milligrams (mg) are effective. However, you should talk with your doctor about how much aspirin (if any) is safe for you.

Digestive problems

It’s common to have digestive problems while taking Tecfidera. These side effects are especially common at the start of treatment. Symptoms often include:

In Tecfidera’s clinical trials, digestive problems occurred most often within the first month of treatment. In some cases, these symptoms were severe enough that some people had to stop treatment.

What you can do

For most people, digestive problems with Tecfidera are temporary. The symptoms should become less bothersome or go away with continued use of the drug.

To help prevent or ease digestive problems from Tecfidera, it’s best to take each dose with food. Consider these other tips to help minimize or prevent digestive side effects:

  • Snack frequently. Some people feel more nausea when their stomach is empty. It may help to keep crackers or dry cereal on hand to snack on.
  • Stay hydrated. When you experience vomiting and diarrhea, you may lose too much fluid. Make sure to drink water or electrolyte replacement beverages to help combat dehydration.
  • Try to avoid foods that may aggravate an upset stomach. Eating fried or spicy foods could make digestive problems such as indigestion or diarrhea worse. Consider choosing non-fried or bland foods for a while after starting treatment with this medication.

It’s important to talk with your doctor if your symptoms don’t go away or become severe. Your doctor may temporarily reduce your dose of Tecfidera to see if the side effects ease.

Less commonly, digestive problems could be a sign of liver damage, a potentially serious side effect of Tecfidera. If this is the case, your doctor may have you temporarily or permanently stop the medication.

Serious infection

People taking Tecfidera may have an increased risk of serious viral, bacterial, or fungal infections. This includes serious infections of the eyes, ears, brain, meninges (tissues surrounding the brain), spinal cord, digestive tract, and lungs.

Serious infections were rare in Tecfidera’s clinical trials. However, since the drug came on the market in 2013, there have been reports of serious infections in people taking it. It isn’t clear how often this has occurred or if Tecfidera was the cause.

A virus called herpes zoster may cause serious infections of the eyes or brain in people taking Tecfidera. (Herpes zoster is also the virus that causes shingles.)

Rarely, people have developed a serious brain infection called progressive multifocal leukoencephalopathy (PML) while taking Tecfidera. This infection is caused by the John Cunningham virus. PML may lead to severe disability, and in some cases, death. Symptoms may include:

  • weakness on one side of the body
  • clumsiness
  • vision changes
  • confusion
  • changes in your personality

During clinical trials of Tecfidera, one person died from PML after taking the drug for 4 years. This person experienced prolonged lymphopenia (low levels of lymphocytes, a type of white blood cell) during the trial.

What you can do

Your doctor will order blood tests to monitor your white blood cell levels before you start taking Tecfidera and regularly during treatment. If you have lymphopenia, your risk of developing infections is higher. Because of this risk, your doctor may not have you start or continue taking the drug.

If you develop symptoms of a possible infection, tell your doctor right away. If they suspect or confirm that you have an infection, they’ll likely treat it. Your doctor will also likely have you stop taking Tecfidera until the infection has cleared up.

Liver damage

In Tecfidera’s clinical trials, some people had certain changes seen on liver function tests. These changes included increased liver enzymes and high bilirubin levels.

These changes can sometimes be an early sign of liver damage. However, in these trials, no one had liver damage.

There have been reports of serious liver problems in people taking Tecfidera. However, it’s unclear how often this has happened or if Tecfidera was the cause.

Symptoms of liver damage can include:

What you can do

Before you start taking Tecfidera, your doctor will check the health of your liver using blood tests. These tests will help your doctor to decide if your liver is working well enough for you to take the drug. During your treatment, your doctor will recheck these tests regularly.

If you develop signs or symptoms of liver damage, your doctor will likely have you stop taking Tecfidera.

Allergic reaction

As with most drugs, Tecfidera can cause an allergic reaction in some people. However, it’s not clear how often allergic reactions occurred in clinical trials.

Symptoms can be mild or serious and can include:

  • skin rash or hives
  • itching
  • 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 you can do

For mild symptoms of an allergic reaction, call your doctor right away. They may recommend ways to ease your symptoms and determine whether you should keep taking Tecfidera. However, if your symptoms are serious and you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Be sure to talk with your doctor about your health history before you take Tecfidera. This drug may not be the right treatment option for you if you have certain medical conditions or other factors that affect your health. The conditions and factors to consider include:

Liver problems. If you have liver problems, it isn’t known if Tecfidera is safe for you. The drug could increase your liver enzyme levels, which can be an early sign of liver damage. If you already have liver problems, this medication could worsen your condition. If you have liver problems, talk with your doctor to see if Tecfidera is safe for you.

Low level of lymphocytes. Taking Tecfidera may lower the level of lymphocytes (certain white blood cells) in your body. These white blood cells are important because they work in your immune system to fight infections. If your lymphocyte levels are already too low, your doctor will likely not prescribe Tecfidera for you. Taking the drug could increase your risk of serious infections.

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

Alcohol with Tecfidera

Alcohol doesn’t cause any interactions with Tecfidera.

However, excessive alcohol consumption may cause some of the same side effects as Tecfidera. These include flushing, nausea, vomiting, and liver problems. So drinking alcohol while taking Tecfidera could worsen these side effects.

If you drink alcohol, talk with your doctor about how much is safe for you to consume while taking Tecfidera.

Pregnancy and breastfeeding while taking Tecfidera

Here’s some information about pregnancy, breastfeeding, and Tecfidera.

Pregnancy. It’s not known if Tecfidera is safe to take during pregnancy. This is because the drug hasn’t been studied in pregnant people.

Negative effects were seen when Tecfidera was studied in pregnant animals. These effects included problems with fetal development as well as reduced offspring survival. However, animal studies don’t always predict what would happen in humans.

If you’re pregnant or planning to become pregnant, talk with your doctor before taking Tecfidera. They’ll help you consider the risks and benefits of the treatment options for your condition.

If you take Tecfidera during your pregnancy, consider participating in the drug’s pregnancy registry. A pregnancy registry serves to collect and provide information about a drug’s safety during pregnancy. You can find out more by calling 866-810-1462 or visiting this website.

Breastfeeding. It’s not known if Tecfidera is safe to take while breastfeeding. Clinical trials haven’t looked at the drug’s effects on breast milk or in children who are breastfed.

If you’re breastfeeding or have plans to breastfeed, talk with your doctor. They can discuss the risks and benefits of different feeding options, including breastfeeding, while taking Tecfidera.

Tecfidera can cause side effects, some of which are more common than others. However, not everyone who takes the drug has side effects. And most of Tecfidera’s common side effects usually go away with continued use of the drug. Serious side effects are possible, however, they’re less common. Be sure to talk with your doctor if you develop any serious side effects during Tecfidera treatment.

If you’d like to learn more about Tecfidera, talk with your doctor or pharmacist. They can help answer any questions you have about side effects of taking the drug.

Besides talking with your doctor, you can do some additional reading on your own. These articles might help:

  • More information about Tecfidera. For details about other aspects of Tecfidera, refer to this article.
  • Drug comparison. To learn how Tecfidera compares with other drugs, read this article.
  • A look at multiple sclerosis (MS). For details about MS, see our MS hub and list of MS articles.

Disclaimer: Medical News Today 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.