Kesimpta (ofatumumab)

Reviewed by: HU Medical Review Board | Last reviewed: April 2023

Kesimpta® (ofatumumab) has been approved to treat relapsing forms of multiple sclerosis (RMS) in adults. This includes clinically isolated syndrome, relapsing-remitting disease (RRMS), and active secondary progressive disease.1

Kesimpta is a first-line treatment option for people RMS. It is given as a subcutaneous (under the skin) injection. People with RMS can give themselves the drug with a Sensoready® autoinjector pen or prefilled syringe. Kesimpta is the first B-cell therapy approved to be self-administered at home.1

What are the ingredients in Kesimpta?

The active ingredient in Kesimpta is ofatumumab.1

How does Kesimpta work?

Kesimpta belongs to a class of drugs called monoclonal antibodies. Monoclonal antibodies are proteins that are made in a lab. They act like human antibodies to restore, enhance, or mimic the immune system’s attack on cells.1,2

The exact way Kesimpta works in people with MS is unknown. Doctors think it sticks to the protein CD20 on the surface of B cells. These are cells that play a key role in the body’s immune response. In people with MS, B cells damage nerves in the brain and spinal cord. Kesimpta works to kill these cells, which reduces inflammation and helps slow down nerve damage.1,2

What are the possible side effects of Kesimpta?

The most common side effects of Kesimpta include:1,2

  • Upper respiratory tract infection
  • Headache
  • Injection-relation reaction, such as fever, chills, headache, muscle pain, fatigue. These usually occur within the first 24 hours following the first injection and can with later injections as well
  • Local injection site reaction, such as redness, swelling, itching, pain

Contact your doctor right away if you have any signs of infection, such as fever, chills, cough, or painful urination.2

These are not all the possible side effects of Kesimpta. Talk to your doctor about what to expect when taking Kesimpta. You also should call your doctor if you have any changes that concern you when taking Kesimpta.

Things to know about Kesimpta

Kesimpta can lower the amount of antibodies in your blood. Antibodies are proteins your immune system makes to kill germs. This makes it harder to fight off infections.2

Kesimpta may reactivate hepatitis B infection. Do not use Kesimpta if you have an active hepatitis B infection. Your doctor will screen you for hepatitis B before prescribing Kesimpta. Your doctor will also screen you for serum immunoglobulins (antibodies).2

Risk of PML

A rare, life-threatening brain infection known as progressive multifocal leukoencephalopathy (PML) has occurred in people with chronic lymphocytic leukemia (CLL) who have taken Kesimpta. The doses of Kesimpta given to these people for their CLL were higher than the doses for MS. While no cases of PML occurred in Kesimpta clinical trials, this is still a possible risk. If you have any symptoms like weakness, clumsiness, vision problems, confusion, or personality changes, contact your doctor right away.2

Live vaccines

You should not get live vaccines during treatment with Kesimpta and for some time after the last dose. Talk to your doctor option your options for vaccines while taking Kesimpta.2


Kesimpta can harm an unborn baby. People who can become pregnant should use birth control during treatment and for 6 months after the last dose of Kesimpta. There isn’t any data on the presence of Kesimpta in breast milk. The risk versus benefit should be evaluated and discussed with your doctor. Talk to your doctor about all of your options for birth control and breastfeeding while taking Kesimpta.2

Have your doctor or nurse teach you how to use Kesimpta and how to dispose of syringes and needles.2

Before beginning treatment for multiple sclerosis, tell your doctor about all your health conditions and any other drugs, vitamins, or supplements you are taking. This includes over-the-counter drugs.

For more information, read the full prescribing information of Kesimpta.

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