Understanding Side Effects

The important stuff

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Let’s talk side effects.

KESIMPTA® (ofatumumab) works by impacting your immune system, so it could increase the risk of getting serious infections, including:
  • Hepatitis B virus (HBV) reactivation: Before starting KESIMPTA, you’ll get a blood test for HBV. If you've ever had HBV infection, it may become active again during or after treatment with KESIMPTA.
  • Progressive multifocal leukoencephalopathy (PML): PML may happen with KESIMPTA. PML is a rare, serious brain infection caused by a virus that may get worse over days or weeks, and can result in death or severe disability.
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Here’s what’s most common:

Injection-related reactions were mostly mild to moderate. They mostly happen with the first injection, although they can happen with later injections.

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Local injection-site reactions

Symptoms include redness, pain, itching, and swelling.

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Injection-related reactions

Symptoms include fever, headache, muscle pain, chills, and fatigue.

Other possible side effects include:

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Upper respiratory infections

Symptoms include sore throat, runny nose, and headache.

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MS=multiple sclerosis.