What to Know about MS Medication Side Effects

By Ann Pietrangelo
Reviewed by Dana Cooper, M.D.
March 27, 2023

If you have multiple sclerosis (MS), you’re probably familiar with disease-modifying therapies (DMTs). The goal of these therapies is to prevent relapses and improve overall quality of life. When it comes to DMTs and other medications you may take to treat MS symptoms, their effectiveness depends on consistently taking them as prescribed—but that can be a challenge if a medication causes unpleasant side effects.

Side effects are a common reason some people might be tempted to skip doses or stop taking their medication, research says. And some people may be reluctant to start a potentially helpful medication because they are concerned about possible side effects.

For any medication, it’s important to balance the potential risk of side effects with the benefit, experts say. Before prescribing MS medications, Sammita Satyanarayan, M.D., a board-certified neurologist at Mount Sinai in New York City, advises patients on the most common side effects that can occur. That way, they can decide together which drug may be the best one to try. “However,” she says, “that isn’t to say that every person will even experience side effects, or that others’ experiences will be predictive of how you feel with the medication.”

Here’s what to know about some common potential side effects of MS medications so that you can help manage them, address any concerns with your doctor, and get the treatment that works best for you.

What Side Effects Can Happen with DMTs?

There are now more than 20 approved DMTs for MS, says Daniel E. Smith, M.D., a board-certified neurologist at OhioHealth in Pickerington, Ohio. “They come in injectable and oral forms, as well as through intravenous infusions,” he says. Smith notes that potential side effects of MS medications are drug-specific and difficult to generalize, but these are a few that may occur.


Smith explains that most DMTs result in some form of immunosuppression, which reduces a person’s immune response. As a result, DMTs may increase the risk of getting certain infections.

How to cope: The level of risk tends to depend on the specific drug a person is prescribed, so be sure to discuss potential risks with your doctor before starting therapy. If you begin to show signs of an infection after you start taking immune-suppressing medications, it’s important to let your doctor know right away.

“Importantly, we have protocols and lab monitoring in place as standard practice to help de-risk these therapies for our patients,” Smith says. In other words, your doctor is keeping a watchful eye for this potential side effect to help address it early, should it occur.

Injection Site Reactions

With injectable medications, it’s possible to experience minor side effects at the injection site. Injection site reactions can include pain, redness, swelling, itching, or burning.

How to cope: There are several ways to help minimize these problems. Try these strategies:

  • If your medication is stored in the refrigerator, let it sit at room temperature for about 20 minutes before use, if your doctor okays it.
  • Apply a warm compress to the injection site for five minutes. Then, clean the site before injecting.
  • Avoid injecting into skin that’s already damaged.
  • Don’t rub the area after injecting.
  • If you want, you can place a cold pack on the site for a minute after injecting.
  • Be sure to switch injection sites according to the instructions that came with your medication.

Flu-Like Symptoms

Some MS medications can cause temporary flu-like symptoms, such as:

  • Tiredness and fatigue
  • Chills
  • Fever
  • Headache
  • Body aches

How to cope: According to the National Multiple Sclerosis Society, these symptoms tend to lessen over time as your body gets used to the medication. In the meantime, to help relieve these side effects if you experience them, you can talk to your doctor about using over-the-counter (OTC) pain and fever reducers such as aspirin, acetaminophen, and nonsteroidal anti-inflammatory drugs (NSAIDs) to make you more comfortable.

Infusion Reaction

An infusion reaction is one that occurs during or just after the administration of an infused drug. An infusion reaction can result in temporary symptoms such as:

  • Itchiness
  • Throat irritation
  • Flushing
  • Rash
  • Headache

An infusion reaction is more likely to occur with your first infusion treatment than subsequent ones. For most people, these side effects are mild to moderate. Very rarely, there can be a more serious reaction.

How to cope: Your healthcare team may give you medications such as steroids and antihistamines before the infusion to help prevent these side effects. Your care provider will also keep a close eye on you for an hour or two after the infusion so that they can watch for and treat any potential infusion reactions.

What About My Other Medications?

Some side effects are also possible with medications used to treat MS symptoms, such as bladder issues, muscle tightness or spasticity, and sensations such as pain, burning, and tingling.

Smith says that some common side effects from neuropathic medications (those that treat nerve pain) and antispasmodic drugs (muscle relaxants) can include cognitive fog, changes in weight and appetite, and fatigue. Some bladder medications are associated with dry mouth and lightheadedness.

People may think that stopping their symptomatic medications is the best way to avoid side effects like these. Symptomatic medications are tailored to each person and what they’re experiencing, explains Smith. Symptoms may be present in the long term, though, and stopping and starting medications abruptly typically won’t help with most of these problems.

“Generally speaking, if they need to be stopped, it is best to taper off these slowly with a plan from your care provider as to the speed and the specifics,” Smith says.

What to Know About Switching or Stopping a Medication

Because MS has such a long list of variable symptoms, it can sometimes be a challenge to know whether you’re dealing with MS medication side effects, symptoms of the condition, or other bodily sensations. See your doctor for their opinion (and advocate for your health if something doesn’t feel right). Your doctor can help you determine whether you’re likely experiencing side effects and figure out the best next steps, which may include switching medication.

Everyone has their own level of tolerance for side effects, and you and your doctor should factor them in when making medication decisions. Side effects may subside over time, and what’s more, there may be strategies to lessen them. When a medication isn’t working well enough to address your symptoms and causes persistent and bothersome side effects, those are good reasons to consider switching medications, says Satyanarayan.

Your doctor should be willing to discuss your options. “Any medication has its own side effect and risk profile, so it’s important to think about the pros and cons of any alternative medication, as well as to take into consideration the risk of not treating or undertreating your MS activity,” Satyanarayan says. You and your doctor should also consider:

  • Your treatment goals
  • The status of your disease activity
  • Your medication history
  • Personal preferences

“We are privileged to be in a position today where we have a multitude of treatment options to choose from,” Satyanarayan says. “At the end of the day, I want a patient’s medication regimen to work best for them, whether that's the efficacy of the drug or how it makes them feel on a day-to-day basis.”

Keep your doctor informed of any MS medication side effects and symptoms you experience so they can help you through. “The most important advice I can give is to keep open communication with your care provider,” Smith says. “They can help counsel on tips and tricks for dealing with a particular side effect, and also advise on when it may be time to stop right away or give the therapy more time.”

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