Understanding Side Effects

Some safety info


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.

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.


Local injection-site reactions

Symptoms include redness, pain, itching, and swelling.


Injection-related reactions

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

Other possible side effects include:

tissue box

Upper respiratory infections

Symptoms include sore throat, runny nose, and headache.



MS=multiple sclerosis.