Generic name: ofatumumab (subcutaneous) [ OH-fa-TOO-mue-mab ]
Other brand names of ofatumumab (subcutaneous) include Kesimpta
Drug classes: CD20 monoclonal antibodies, Selective immunosuppressants

Medically reviewed by Drugs.com on Aug 20, 2024. Written by Cerner Multum.

What is ofatumumab?

Ofatumumab is used to treat relapsing forms of multiple sclerosis in adults (including clinically isolated syndrome, relapsing-remitting disease, and active secondary progressive disease).

Ofatumumab may also be used for purposes not listed in this medication guide.

Ofatumumab side effects

Get emergency medical help if you have signs of an allergic reaction: hives, difficult breathing, swelling of your face, lips, tongue, or throat.

Some side effects may occur during the injection. Tell your medical caregivers if you feel dizzy, nauseated, light-headed, itchy, sweaty, or have a headache, chest tightness, back pain, trouble breathing, or swelling in your face.

Ofatumumab may cause a brain infection that can lead to disability or death. Tell your doctor if you have problems with speech, thought, vision, or muscle movement. These symptoms can get worse quickly.

Kesimpta may cause serious side effects. Call your doctor at once if you have:

• an active or chronic infection, including hepatitis B;

• pain or burning when you urinate;

• pain, redness, swelling, or itching where the medicine was injected; or

• right-sided upper stomach pain, vomiting, loss of appetite, yellowing of your skin or eyes, and not feeling well.

Your cancer treatments may be delayed or permanently discontinued if you have certain side effects.

Common side effects of Kesimpta may include:

• bruising, swelling, warmth, redness, oozing, or bleeding where an injection was given;

• fever, cold symptoms such as stuffy nose, sneezing, sore throat;

• cough, chest tightness, trouble breathing, lung infection; or

• headache, tiredness, muscle aches.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Related/similar drugs

Warnings

You may get infections more easily, even serious or fatal infections. Call your doctor if you have flu symptoms, cough, night sweats, neck stiffness, confusion, or vision problems.

Ofatumumab may cause a brain infection that can lead to disability or death. Call your doctor if you have problems with speech, thought, vision, or muscle movement.

If you've had hepatitis B, it may come back or get worse. Tell your doctor if you don't feel well and you have right-sided upper stomach pain, vomiting, loss of appetite, or yellowing of your skin or eyes.

Before taking this medicine

You should not use ofatumumab if you are allergic to it, or if you have:

• an active hepatitis B infection.

Tell your doctor if you have ever had:

• an active or chronic infection;

• a condition for which you have used an immunosuppressant medication; or

• hepatitis B.

Make sure you are current on all vaccines before you start using ofatumumab. Tell your doctor if you have received any vaccines within the past 2 weeks or are scheduled for a booster dose.

May harm an unborn baby. You may need a pregnancy test to make sure you are not pregnant. Use effective birth control while using ofatumumab and for at least 6 months after your last dose. Tell your doctor if you are pregnant or plan to become pregnant.

If you are pregnant, your name may be listed on a pregnancy registry to track the effects of ofatumumab on the baby.

Ask a doctor if it is safe to breastfeed while using this medicine.

How should I use ofatumumab?

Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.

Your doctor will perform tests to make sure ofatumumab is the right treatment for you.

Ofatumumab is injected under the skin, usually once per month. The first 3 doses are given weekly.

Ask your doctor or pharmacist if you don't understand how to use an injection.

Prepare an injection only when you are ready to give it. Call your pharmacist if the medicine looks cloudy, has changed colors or has particles in it.

Throw away a prefilled syringe after one use, even if there is still medicine left inside.

Do not reuse a needle or syringe. Place them in a puncture-proof "sharps" container and dispose of it following state or local laws. Keep out of the reach of children and pets.

Avoid injecting ofatumumab into scars, moles, or stretch marks, or into skin that is red, bruised, scaly, hard, or tender.

Your blood will be tested before, during, and after treatment with ofatumumab, and your next dose may be delayed based on the results.

You may be given medication to prevent certain side effects.

Store this medicine in the original container in the refrigerator away from light, do not freeze. Do not shake the medicine.

Ofatumumab can be stored at room temperature for up to 7 days. If not used, the medicine should be returned to the refrigerator and used within 7 days. Throw away any medicine not used within that time.

What happens if I miss a dose?

Use the medicine as soon as you remember, and then go back to your regular schedule. Do not use two doses at one time.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while using ofatumumab?

You should not receive a vaccine while using ofatumumab.

What other drugs will affect ofatumumab?

Tell your doctor about all your other medicines, especially:

• drugs that weaken the immune system such as cancer medicine, steroids, and medicines to prevent organ transplant rejection.

This list is not complete. Other drugs may affect ofatumumab, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.

Biological Products Related to Kesimpta

Find detailed information on biosimilars for this medication.

Popular FAQ

View more FAQ

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Medical Disclaimer

Copyright 1996-2025 Cerner Multum, Inc. Version: 1.01.