Dimethyl fumarate (Tecfidera)

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• Who can take dimethyl fumarate (Tecfidera)?
• How does dimethyl fumarate (Tecfidera) work?
• How well does dimethyl fumarate (Tecfidera) work?
• Dimethyl fumarate (Tecfidera) side effects
• Stopping dimethyl fumarate (Tecfidera)
• What tests do you need with dimethyl fumarate (Tecfidera)?
• Dimethyl fumarate (Tecfidera) and pregnancy, breastfeeding and contraception

Who can take dimethyl fumarate (Tecfidera)?

Dimethyl fumarate (Tecfidera) is recommended for people with ‘active’ relapsing MS. That means you’ve had a recent relapse, or MRI scans show new, active or growing lesions (areas of damage) in your brain or spinal cord.

You might be offered a ‘generic’ version of this DMT with a different brand name. It works just as well as Tecfidera.

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How does dimethyl fumarate (Tecfidera) work?

We don't know exactly how dimethyl fumarate (Tecfidera) works, but it dampens down inflammation. This may be helpful in reducing the inflammation that causes damage in the brain and spinal cord of people with MS.

Dimethyl fumarate is a tablet you take twice a day. Taking it with food may help reduce some of its side effects. 

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How well does dimethyl fumarate (Tecfidera) work?

The effectiveness of dimethyl fumarate (Tecfidera) is classed as ‘good’. Each DMT can be rated as ‘moderate’, ‘good’ or ‘high’. This is based on how much it can reduce relapses and slow down disability getting worse.

Relapses dropped by 53% compared to placebo

In the two-year DEFINE trial, on average, people saw a 53% drop in the number of relapses they had. This was compared to people who took a placebo, a dummy treatment with no drug in it.

Disability getting worse was slowed by 38% compared to placebo

In the DEFINE trial, on average, people saw a 38% drop in the risk of their disability getting worse. This was compared to people who took a placebo.

A second two-year trial of dimethyl fumarate, called CONFIRM, had similar results.

Long-term results 

Dimethyl fumarate (Tecfidera) continues to work well over many years. The ENDORSE study followed people for up to 11 years. It continued to follow 1,736 people who had taken part in the DEFINE and CONFIRM trials. Over this longer period, dimethyl fumarate continued to work well and no new side effects were found.

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Dimethyl fumarate (Tecfidera) side effects

Very common side effects (more than 1 in 10 people get them):

• flushing (going red in the face)
• feeling hot
• upset stomach
• feeling sick

Common side effects (up to 1 in 10 people get them):

• being sick
• indigestion
• itchy skin
• rash
• hair loss
• a drop in white blood cells (lymphopenia)

Side effects usually get better after a few weeks. Talk to your MS team about ways you can manage side effects. Medicines you can buy over the counter may help, like antacids or anti-diarrhoea medicines.

Flushing and stomach problems are the most common side effects. Taking an aspirin half an hour before you take dimethyl fumarate (Tecfidera) can help with flushing. Taking the drug just after food may help with flushing and with stomach problems.

Find out more about all the possible side effects of dimethyl fumarate (Tecfidera)

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Stopping dimethyl fumarate (Tecfidera)

You should never stop taking a DMT without telling your neurologist. With some DMTs, if you suddenly stop, there’s a risk of ‘rebound’. This is when your MS gets much worse within a few weeks or months. This has happened with dimethyl fumarate (Tecfidera) but it’s not common.

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What tests do you need with dimethyl fumarate (Tecfidera)?

Dimethyl fumarate may affect your kidneys and liver and how many white blood cells you have. So you’ll have blood tests before treatment and every three months during it. You may also have tests on your pee before and during treatment.

Like most DMTs, this drug makes infections more likely. Before you start it, your neurologist will check if you have protection against some of the infections it puts you at risk of. 

Your neurologist will check you’re up to date on your vaccines. This includes childhood ones like chickenpox (that vaccine protects you against shingles) and the MMR vaccine for measles, mumps and rubella. Some ‘live’ vaccines, like these two, aren’t safe to have once you’ve started many DMTs. Your MS team or GP can tell you whether a vaccine is ‘live’ or not. 

You’ll have any vaccines you need a few weeks before you start this drug. 

You can safely have the annual flu jab while taking this DMT. 

Read more about vaccines 

Your neurologist might want you to have an MRI scan once a year to see if the drug is working. But how often you have scans depends on what your neurologist thinks you need. If your MS seems stable, you might have scans less often.

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Dimethyl fumarate (Tecfidera) and pregnancy, breastfeeding and contraception

Pregnancy

Dimethyl fumarate (Tecfidera) isn’t licensed to be used during pregnancy. There’s no evidence that this drug harms babies in the womb. In animal studies it harmed the unborn. We need more studies into whether it can do this with people, although some studies have found it was safe in pregnancy.

Guidelines say it’s best to avoid getting pregnant while taking this drug. If you think you’re pregnant, get medical advice at once about coming off the drug. 

Your neurologist may recommend you keep taking this drug through your pregnancy, if the benefits outweigh the risks. 

If you can get pregnant, talk to your neurologist. You can talk about the benefits and risks of taking dimethyl fumarate while pregnant, and whether to switch to a different DMT.

There’s no set time for the ‘wash out period’ for this drug but doctors might recommend a month or less. This is how long it takes for the drug to leave your body.

If you want to have a child, discuss this with your neurologist or MS nurse. If you think you’ve become pregnant, let your medical team know at once. Never stop your DMT without first getting their advice.

Breastfeeding

It’s not clear if dimethyl fumarate (Tecfidera) gets into breast milk. It’s recommended that you don’t breastfeed while on this treatment.

Contraception

If you can get pregnant, you should use reliable contraception while taking dimethyl fumarate (Tecfidera), like ‘the pill’, condoms, a coil, injections or implant.

Stomach problems are a common side effect of this drug, especially early on. If you’re on the pill, this might stop it working. So you might need extra contraception until this side effect stops.

Read more about pregnancy, breastfeeding and contraception and DMTs

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