Is Your MS Medication Working?

How to Tell If It Isn't

Though multiple sclerosis (MS) is an incurable condition, disease-modifying therapies (DMTs) can help prevent relapses and slow the natural progression of the disease. That said, selecting the right DMT when diagnosed with MS can be a challenging task. A number of factors must be taken into consideration, including how active your disease is and the drug's side effects.

Even then, sometimes a person's disease stops responding to their chosen DMT, warranting a switch in medication. This article will review the factors that affect how effective a DMT is and the signs that your therapy may not be working.

Person with multiple sclerosis discusses brain MRI with neurologist

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Factors That Affect MS Medication Efficacy

There are nine classes of DMTs available, all unique in their mode of action and efficacy (level of effectiveness).

Monoclonal antibody DMTs, like Ocrevus (ocrelizumab), are considered highly effective in reducing relapses. This is because they target specific markers or pathways within a person's immune system.

In contrast, the older DMTs, like the interferon beta drugs, work more generally on the immune system. They may not be as effective in reducing relapses for patients with an aggressive MS course.

Besides the innate mode of action, other factors that affect a DMT's efficacy include:

  • Whether a person with MS adheres to taking their medication
  • If the person is taking other drugs that interact with their MS DMT
  • How active or aggressive a person's disease is when they start their DMT

Signs Treatment Isn’t Working

The primary goal of taking a DMT is to prevent MS disease activity.

MS disease activity is measured in three different ways:

The occurrence of any of the above may be a sign that your DMT isn't working. Although, keep in mind that it takes months, if not over a year, for most DMTs to reach their full effect.

To formally measure your response to a DMT, your neurologist can calculate your Rio score. The Rio score (modified in 2012) ranges from 0 to 3.

One year after treatment, a person with MS receives 1 point if six or more new lesions are seen on their MRI, or if they experience a relapse. They receive 2 points for two or more relapses.

Interpretation of the Rio score is as follows:

  • A score of 0 means that you are responding well to your DMT.
  • A score of 2 or 3 means you are not responding well to your DMT and would probably benefit from changing drugs.
  • A score of 1 is considered indeterminate. It requires a repeat score analysis after six months. At that point, if you have a relapse or more than one new lesion on your MRI, a DMT switch should be considered.

The Flip Side: Signs Your MS DMT Is Working

Three signs that your DMT is effective (in the last six to 12 months) are:

  • You are not experiencing new relapses.
  • Your MRIs have not revealed any new lesions.
  • Your physical abilities have remained stable.

At Your Next Neurologist Appointment: Discussing Concerns

After starting your DMT, it's important to be open and honest with your neurologist (a specialist for conditions of the nervous system). Don't hesitate to ask questions and discuss any concerns you have.

Whether you are worried about side effects, drug effectiveness, or are anticipating a move, pregnancy, or change in insurance, communicating any care concerns early and often with your neurologist can minimize any potential negative impact on your MS care.

Keep in mind that at your follow-up appointments, your neurologist will also ask you about new, worsening, or recurring neurological symptoms. They will also perform a neurological examination.

Depending on the DMT you are on, you may also need to undergo various blood tests, like a complete blood count (CBC) or liver function panel.

Screening for the John Cunningham (JC) virus is also required for people taking Tysabri. This is due to the increased risk of developing progressive multifocal leukoencephalopathy (PML), a rare brain infection.

Timing of Next MRI

At your appointment, your neurologist may also order an MRI to see if you have developed any new lesions, regardless of whether or not you are having symptoms.

A brain MRI is generally ordered before starting or switching a DMT, and then repeated three to six months later, followed by yearly scans thereafter.

General Reminders

Taking a disease-modifying therapy is essential to preventing relapses, delaying MS-related disability and, ultimately, caring for your future self. All said, choosing the right DMT and sticking with it can be a difficult process. You may find taking the medication costly, inconvenient, or unpleasant.

Also, it may be hard to grasp its benefits, considering DMTs are long-term, "behind-the-scenes" therapies. They do not treat daily MS symptoms like pain, fatigue, or numbness.

To help you navigate the treatment part of life with MS, consider these tips and reminders:

  • To help stay organized, consider using a pillbox, phone alarm, or arranging for telephone or text message reminders.
  • Ask loved ones for assistance with sticking to your treatment plan.
  • Continue to gain knowledge and stay up-to-date on the latest MS research.
  • If you have financial concerns, contact your neurologist, drug manufacturer, and/or patient assistance programs through the National Multiple Sclerosis Society.


MS is an incurable disease, but there are multiple disease-modifying therapies (DMTs) available that can help reduce relapses and slow the course of the disease. Sometimes, though, your MS medication stops working, as evidenced by new relapses, MRI lesions, and/or disability progression. When a DMT stops being effective, your neurologist will probably switch you to a new drug.

A Word From Verywell

As you navigate the physical, emotional, and logistical obstacles of living with MS, remember to set aside time for self-care and enjoyment. Some people find that journaling, meditating, or engaging in deep breathing exercises can help provide comfort and ease stress. You may also consider joining an MS support group as a social outlet and source of encouragement.

Frequently Asked Questions

  • What side effects are red flags that MS medication isn’t working?

    There are multiple MS disease-modifying therapies, all varying in their side effect profiles. Experiencing side effects is not a sign that a drug is not working.

    Rather, signs that your MS medication isn't working are if you continue to have severe or multiple relapses, you develop new MRI lesions, or your disability worsens after being on that medication for a year.

  • Why is PML a side effect of some MS medications?

    PML is a rare, potentially fatal brain disease caused by infection with or reactivation of the John Cunningham virus (JC virus). Since MS disease-modifying therapies (DMTs) change how your immune system works, people who take certain DMTs are at a higher risk of contracting (or reactivating) the JC virus.

  • Is it safe to stop MS medications suddenly?

    It's important to not stop your MS medication, unless under the guidance of your neurologist. Stopping your medication, especially if done suddenly without preparation for the next treatment steps, may worsen your MS activity.

10 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Colleen Doherty, MD
 Colleen Doherty, MD, is a board-certified internist living with multiple sclerosis.