As cold and flu season approaches, people living with multiple sclerosis (MS) — especially those on certain disease-modifying therapies (DMTs) — may face a higher risk for infections. A new study from Cleveland Clinic adds to what’s already known: Some high-efficacy (HE) DMTs can modestly increase your risk for infections.

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With the right precautions and regular check-ins with your healthcare team, you can stay protected and continue benefiting from your treatment.

Understanding the Research

The Cleveland Clinic study looked at nearly 3,900 people with MS treated between 2017 and 2023. Although serious infections are not a common side effect of MS treatment, the study found those using ocrelizumab (Ocrevus) had roughly twice the rate of serious infections compared with people taking older injectable therapies like interferon beta or glatiramer acetate.

Specifically, over an average of three years of treatment, serious infections occurred in roughly 4.2 out of every 100 people each year among ocrelizumab users, compared with about 2.6 out of every 100 people each year on injectable medications.

Respiratory infections were the most common, followed by urinary tract and skin infections. Researchers noted that infection risk didn’t rise significantly with age — and that lower levels of antibodies (immunoglobulins) weren’t clearly linked to more infections in this study.

Why Risk Can Differ by Treatment

Ocrelizumab is one of several HE DMTs — medications that powerfully suppress immune activity to reduce relapses and slow MS progression. HE DMTs include treatments such as:

• Alemtuzumab (Lemtrada)
• Cladribine (Mavenclad)
• Fingolimod (Gilenya)
• Natalizumab (Tysabri)
• Ofatumumab (Kesimpta)

Because these drugs work by calming or depleting parts of the immune system, they can make you more prone to infections than the general population. Still, their ability to prevent MS relapses and disability progression often outweighs these risks — making ongoing care and communication with your healthcare team especially important.

Protecting Yourself During Cold and Flu Season

If you’re taking ocrelizumab or another high-efficacy DMT, you can lower your chances of infection and stay ahead of any potential problems by taking a few precautions:

• Stay current on vaccines. Ask your doctor about flu, COVID-19, and shingles vaccines, and whether timing matters based on your DMT schedule.
• Practice good hygiene. Wash your hands often, avoid close contact with people who are sick, and consider masking in crowded indoor spaces during outbreaks.
• Check in regularly with your neurologist. Routine bloodwork can help you track immune function and spot potential changes early.
• Report symptoms right away. Persistent cough, fever, urinary changes, or unusual fatigue could signal an infection worth checking.
• Support your immune system. Prioritize rest, hydration, and balanced nutrition — all of which can help your body recover faster if you do get sick.

Talk to Your Healthcare Team

Talk with your healthcare provider about your personal risk factors and what preventive measures make the most sense for you this season.

Learn more about the most effective treatments for MS — including their benefits and side effects.

Join the Conversation

On MyMSTeam, people share their experiences with multiple sclerosis, get advice, and find support from others who understand.

Have you or a loved one experienced infections while on ocrelizumab or another MS treatment? Let others know in the comments below.