Most Common Side Effects of Ocrevus
Ocrevus (ocrelizumab), approved for relapsing and primary progressive multiple sclerosis (MS), most often causes infusion reactions in up to 40% of patients during or within 24 hours of administration. These include itching, rash, nausea, fatigue, headache, flushing, fever, and swelling. Premedication with antihistamines, acetaminophen, and corticosteroids reduces severity.[1][2]
Upper respiratory tract infections occur in about 40% of users, alongside lower respiratory infections in 10%. Patients also report mild increases in urinary tract infections.[1]
Infusion-Specific Reactions
First infusions carry higher risk (nearly 50% affected) compared to later ones (under 35%). Serious reactions like anaphylaxis or life-threatening events happen in under 1%, but monitoring for 1 hour post-infusion is standard. Symptoms peak within hours and resolve quickly for most.[1][2]
Why Infections Are Frequent
Ocrevus depletes B cells, weakening immune response and raising infection risk. Opportunistic infections (e.g., herpes reactivation) affect 7-10%; hepatitis B screening is required pre-treatment to avoid reactivation.[1]
Long-Term Risks Patients Report
Over years, 1-2% develop malignancies like breast cancer (observed more than expected). Liver enzyme elevations occur in 10%, and low immunoglobulin levels increase infection vulnerability. Progressive multifocal leukoencephalopathy (PML) risk is low (under 0.1 cases per 1,000).[1][2]
How Side Effects Differ by MS Type
Relapsing MS trials showed similar profiles to progressive MS, but progressive patients had slightly higher serious infection rates (9% vs. 6%). No major differences in infusion reactions.[1]
What to Watch During Pregnancy or Breastfeeding
Avoid during pregnancy due to B-cell depletion risks to fetus; effective contraception advised for 12 months post-last dose. Data on breastfeeding is limited.[2]
Sources
[1]: Ocrevus Prescribing Information (FDA)
[2]: OCREVUS HCP Site (Genentech)