Disease-modifying drugs (DMDs) are an important part of treatment for multiple sclerosis (MS). But while they can make a big impact on the disease, these drugs can cause side effects. If your doctor suggests a DMD for you, it’s important to understand the benefits and risks of DMDs before taking them.

Each DMD has different factors you should discuss with your doctor. Read on to learn about the benefits and side effects that apply to all DMDs.

Side effects of DMDs

Although DMDs have important benefits, they can cause a range of side effects. Your side effects will depend on the type of DMD you take.

Mild side effects

The more common side effects of all types of DMDs are usually short-term, and may include:

  • tiredness
  • depression
  • flu-like symptoms, including chills and fever
  • pain in your abdomen
  • diarrhea
  • nausea
  • muscle aches
  • rash
  • headache
  • infection in your upper respiratory tract
  • decreased levels of white blood cells
  • hair loss
  • reaction at the injection site (for injected DMDs)

Serious side effects

Rare but serious side effects also vary by the type of DMD. These side effects can include:

  • heart rhythm problems
  • heart failure
  • anaphylaxis (serious allergic reaction)
  • liver damage
  • increased risk of certain cancers
  • autoimmune disorders
  • clots in small blood vessels
  • kidney failure
  • swelling in the back of your eye
  • progressive multifocal leukoencephalopathy (PML)

Managing side effects of DMDs

Your side effects will depend on the specific DMD you take. Part of coping with your side effects is knowing what to expect. Be sure to talk to your doctor or pharmacist about likely side effects. They can give you tips on what symptoms to look for, how to manage side effects, and when to call your doctor.

For a few of the more common side effects of DMDs, you can try over-the-counter treatments:

  • For muscle aches, fever, or headache, use pain relievers such as acetaminophen (Tylenol), ibuprofen (Advil), or naproxen (Aleve).
  • For diarrhea, use loperamide (Imodium) or bismuth subsalicylate (Pepto-Bismol).
  • For rash, use diphenhydramine (Benadryl) or hydrocortisone.

You can also look on the website for your particular drug. Manufacturers often provide information on how to manage side effects and when to call your doctor.

Benefits of DMDs

Despite side effects, the benefits of DMDs can be significant. MS causes nerve damage that’s permanent. No medication can reverse it, but DMDs can help delay this nerve damage for as long as possible. According to a paper by the Multiple Sclerosis Coalition, starting a DMD right away can help even if you’ve had only one clinical episode of MS and you don’t have symptoms. DMDs help in several ways.

Slowing the progress of disease and disability

MS is a progressive disease, which means it gets worse over time. Even if your condition doesn’t seem to be getting worse at the moment, most MS specialists would encourage you to start and stay on a DMD. Damage that can’t be reversed can occur early in the disease process. If you start treatment with a DMD right away, that damage can be slowed. In that way, a DMD can help delay disability and lessen the amount of disability you have.

Reducing the number of relapses

Relapses are also called flares or exacerbations. They’re periods of increased or new MS symptoms that last at least 24 hours.During a relapse, your nerves, brain, and spinal cord may be damaged. DMDs reduce the number of relapses by increasing the amount of time between them. This slows the damage the disease can cause.

Improving quality of life

Taking DMDs improves quality of life for people with MS. This may be partly because people who take DMDs have fewer relapses. But also, research shows that people who don’t take DMDs have more mental changes, depression, and fatigue earlier in the disease process. All of these effects can take a toll on your quality of life.

Other considerations for safe use

If a DMD is an option for you, you should talk to your doctor about other drugs or health conditions you have.A DMD might interact with another drug you take or be unsafe for a condition you have. Be sure to tell your doctor about all medications you take, as well as your entire health history.

Be sure to discuss any preferences you have with your doctor. DMDs can come as pills or injectable forms. Also, before starting a DMD, you’ll likely want to make sure your insurance will cover it. Your doctor can help you find that out. If you need more information on insurance coverage and financial issues, visit the website for the National Multiple Sclerosis Society.


DMDs are a key treatment option for people with MS. Many types are available to help slow the progress of your MS, reduce relapses, and help you live a fuller life.

To decide if a DMD is a good choice for you, talk with your doctor. Together, you can explore all of the factors that might affect your decision, such as possible side effects. Because DMDs can have very noticeable side effects, you’ll want to talk to your doctor about what symptoms to watch for. You can return to this conversation later to discuss how to manage any side effects that do affect you.



I have MS, but I feel fine and I’m worried about side effects from DMDs. Can I delay taking a DMD for a while?


That’s a decision you’ll need to make with your doctor. Together, you may decide that you’ll wait before starting a DMD. However, it’s more likely that your doctor will suggest that you start taking one sooner rather than later. This is because DMDs typically work best when given early in the disease process. Research shows that delaying DMDs for even 1 or 2 years could be harmful. Research also shows that DMDs are a good idea for people with even mild forms of MS. This is because people taking DMDs show less damage in their brain and have fewer relapses of MS.

the Healthline Medical TeamAnswers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.