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CD20 monoclonal antibodies single-dose prefilled Sensoready pen for subcutaneous use (2…

Kesimpta

Generic name: ofatumumab

Last updated September 16, 2026 0 views Reviewed by Carmen Pope, Senior Medical Editor, B. Pharm
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What is Kesimpta?

Kesimpta is used to treat relapsing forms of multiple sclerosis (MS), including clinically isolated syndrome, relapsing-remitting disease, and active secondary progressive disease, in adults. It is self-administered once a month by subcutaneous injection after an initial dosing period.

Exactly how Kesimpta works is unknown, but it is thought to involve binding to CD20, a protein present on pre-B and mature B lymphocytes (lymphocytes are a type of white blood cell that are more abundant in people with MS). Once bound to the B-cell, Kesimpta triggers the destruction of the cell. Clinical trials report that Kesimpta slows MS progression and reduces the rate of relapse, but it is not a cure. Kesimpta belongs to the drug class called CD20-directed cytolytic antibodies. It may also be called a selective immunosuppressant.

Kesimpta (ofatumumab) gained FDA approval on October 26, 2009. There is no generic or biosimilar. Kesimpta is not interchangeable with another brand of ofatumumab called Arzerra used for CLL.

How should I use Kesimpta?

See the detailed Instructions for Use that come with the Kesimpta Package Insert for information about how to prepare and inject a dose of this medicine and how to properly throw away (dispose of) used Sensoready pens or prefilled syringes.

  • Use Kesimpta exactly as your healthcare provider tells you to use it.
  • Kesimpta is given as an injection under your skin (subcutaneous injection), in your thigh or stomach area (abdomen) by you or a caregiver. A caregiver may also give you an injection in your upper outer arm. See Where and how is Kesimpta injected? for more information.
  • Your healthcare provider will show you how to prepare and inject this medicine the right way before you use it for the first time.
  • Do not inject into areas where the skin is tender, bruised, red, scaly, or hard. Avoid areas with moles, scars, or stretch marks.

Before using Kesimpta

Do not use Kesimpta if you:

  • have an active hepatitis B virus infection
  • have had an allergic reaction to ofatumumab, Kesimpta, or a life-threatening injection-related reaction to Kesimpta.

Before using this medicine, tell your healthcare provider about all of your medical conditions, including if you:

  • have or think you have an infection, including HBV or PML (see Important information above)
  • have ever taken, currently take, or plan to take medicines that affect your immune system. These medicines could increase your risk of getting an infection
  • have a history of liver problems
  • have had a recent vaccination or are scheduled to receive any vaccinations. You should receive any required ‘live’ or ‘live-attenuated’ vaccines at least 4 weeks before you start treatment. You should not receive ‘live’ or ‘live-attenuated’ vaccines while you are being treated with this medicine and until your healthcare provider tells you that your immune system is no longer weakened. Whenever possible, you should receive any ‘non-live’ vaccines at least 2 weeks before you start treatment with Kesimpta. Talk to your healthcare provider about vaccinations for your baby if you used Kesimpta during your pregnancy. Your baby should not receive 'live' vaccines until blood tests show their immune system is back to normal.
  • are pregnant, think you might be pregnant, or plan to become pregnant. Kesimpta may harm your unborn baby. Females who can become pregnant should use birth control (contraception) during treatment with this medicine and for 6 months after your last treatment. Talk with your healthcare provider about what birth control method is right for you during this time.

Pregnancy Registry: There is a registry for women who become pregnant during treatment with Kesimpta. If you become pregnant while taking Kesimpta, tell your healthcare provider right away. Talk to your healthcare provider about registering with the MotherToBaby Pregnancy Study in Multiple Sclerosis.

The purpose of the registry is to collect information about your health and your baby’s health. For moreinformation or to register, contact MotherToBaby by calling 1-877-311-8972, by sending an email to [email protected], or go to www.mothertobaby.org/join-study.

  • are breastfeeding or plan to breastfeed. It is not known if Kesimpta passes into breast milk. Talk to your healthcare provider about the best way to feed your baby if you take this medicine.

Before starting Kesimpta, your healthcare provider will screen for the hepatitis B virus (HBV) and obtain blood tests for immunoglobulins, aminotransferases, alkaline phosphatase, and bilirubin.

Side effects

Common side effects

The most common side effects of Kesimpta are:

  • upper respiratory tract infections with symptoms such as a sore throat, runny nose, and headache
  • headaches.

Important information: serious side effects and warnings

Kesimpta can cause serious side effects, including:

  • Infections. Serious infections, which can be life-threatening or cause death, can happen during treatment with Kesimpta. If you have an active infection, your healthcare provider should delay your treatment until your infection is gone. Kesimpta taken before or after other medicines that weaken the immune system may increase your risk of getting infections. Tell your healthcare provider right away if you have any infections or get any symptoms, including painful and frequent urination, nasal congestion, runny nose, sore throat, fever, chills, cough, or body aches. Hepatitis B virus (HBV) reactivation. Before starting treatment, your healthcare provider will do blood tests to check for HBV. If you have ever had an HBV infection, the HBV may become active again during or after treatment. Hepatitis B virus becoming active again (called reactivation) may cause serious liver problems, including liver failure or death. You should not receive this medicine if you have active hepatitis B liver disease. Your healthcare provider will monitor you for HBV infection during and after you stop using this medicine.

Tell your healthcare provider right away if you get worsening tiredness or yellowing of your skin or the white part of your eyes during treatment.

  • Progressive Multifocal Leukoencephalopathy (PML). PML may happen with this medicine. PML is a rare, serious brain infection caused by a virus that may get worse over days or weeks. PML can result in death or severe disability. Tell your healthcare provider right away if you have any new or worsening neurologic signs or symptoms. These may include weakness on one side of your body, loss of coordination in arms and legs, vision problems, and changes in thinking and memory, which may lead to confusion and personality changes. Weakened immune system. Kesimpta taken before or after other medicines that weaken the immune system could increase your risk of getting infections.
  • Injection-related reactions. Injection-related reactions are a common side effect of Kesimpta. These can happen within 24 hours (1 day) following the first injection and with later injections. There are 2 kinds of reactions: at or near the injection site: redness of the skin, swelling, itching, and pain. Talk with your healthcareprovider if you have any of these signs and symptoms. those that may happen when certain substances are released in your body: fever, headache, pain in the muscles, chills, tiredness, rash, hives, trouble breathing, swelling of the face, eyelids, lips, mouth, tongue, and throat, and feeling faint, or chest tightness. Contact your healthcare provider right away if you experience any of these signs and symptoms, especially if they become worse or you have new severe signs of reactions after subsequent injections. It could be a sign of an allergic reaction, which can be serious.
  • Low immunoglobulins. Kesimpta may cause a decrease in some types of antibodies. Your healthcare provider will do blood tests to check your blood immunoglobulin levels.
  • Liver damage. Kesimpta may cause liver damage. Your healthcare provider will do blood tests to check your liver before you start Kesimpta and while you take Kesimpta if needed. Tell your healthcare provider right away if you have any symptoms of liver damage, such as: yellowing of the skin and eyes (jaundice) nausea vomiting unusual darkening of the urine feeling tired or weak.

These are not all the possible side effects of Kesimpta. Call your healthcare provider for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Dosing information

Dosage of Kesimpta for relapsing forms of Multiple Sclerosis

  • Weeks 0, 1, 2: 20 mg subcutaneously (SC)
  • Week 3: No injection
  • Week 4 and monthly thereafter: 20 mg subcutaneously (SC)

What happens if I miss a dose?

If you miss an injection of Kesimpta at Week 0, 1, or 2, talk to your healthcare provider. If you miss a monthly injection, give it as soon as possible without waiting until the next scheduled dose. After that, use your injections a month apart.

What other drugs will affect Kesimpta?

Tell your doctor about all your other medicines, especially drugs that weaken the immune system such as

  • cancer medicine
  • steroids
  • medicines to prevent organ transplant rejection.

This list is not complete. Other drugs may affect Kesimpta, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here. Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements. Know the medicines you take. Keep a list of them to show your healthcare provider and pharmacist when you get a new medicine.

Storage

Store Kesimpta in a refrigerator between 36°F and 46°F (2°C and 8°C). Keep it in the original carton until ready for use to protect it from light.

If needed, Kesimpta may be stored for up to 7 days at room temperature, up to 86°F (30°C ). Write the date taken out of the refrigerator in the space provided on the carton.

If stored below 86°F (30°C), unused Kesimpta may be returned to the refrigerator and must be used within the next 7 days. If this Kesimpta is not used within those 7 days, then discard the medicine.

Do not freeze. Do not shake.

Keep out of the reach of children.

Ingredients

Active ingredient: ofatumumabInactive ingredients (pen and prefilled syringe): arginine, disodium edetate, polysorbate 80, sodium acetate trihydrate, sodium chloride, and Water for Injection. Hydrochloric acid may be added.

Available as:

  • Single-dose prefilled Sensoready Pen 20 mg/0.4 mL
  • Single-dose prefilled syringe 20 mg/0.4 mL.

Kesimpta (ofatumumab) is distributed by Novartis Pharmaceuticals Corporation, East Hanover, New Jersey 07936. For more information, go to www.novartis.us or call 1-888-669-6682.

Common questions about Kesimpta

What are Monoclonal Antibodies and how do they work?
Monoclonal antibodies (mAbs) are man-made proteins that mimic the natural antibodies produced by our immune systems. Monoclonal antibodies can be formulated into medicines to treat various types of illnesses, such as cancer, rheumatoid arthritis or psoriasis. Continue reading
Is Kesimpta better than Ocrevus?
Kesimpta (ofatumumab) may offer advantages over Ocrevus (ocrelizumab) for treating relapsing forms of multiple sclerosis (MS), particularly in reducing relapse rates and offering convenient at-home administration. However, no prospective head-to-head clinical trial has directly compared these two drugs. Both are prescribed for relapsing MS, but Ocrevus is the only FDA-approved option for primary progressive MS (PPMS), making it the clear choice for that indication. Continue reading
How long can Kesimpta be out of the fridge?
Kesimpta (ofatumumab) can be kept at room temperature for up to 7 days, as long as the temperature doesn’t get higher than 30 degrees C (86 degrees F). Continue reading
How long does it take for Kesimpta to work?
Kesimpta (ofatumumab) begins working in your body after your first injections by quickly lowering certain B cells that drive inflammation in multiple sclerosis (MS). In clinical studies, many people noticed benefits, such as fewer MS relapses and reduced disease activity, within about 2 weeks. For others, it took up to 12 weeks (around 3 months) to see the full effect. Continue reading
Where and how is Kesimpta injected?
Kesimpta (ofatumumab) is injected under the skin (subcutaneously). It should be injected into the stomach area, thigh, or outer upper arm. Continue reading
How is Arzerra administered and how long to work?
Arzerra (ofatumumab) was administered by an intravenous infusion. Arzerra has now been discontinued. Continue reading

Related medicines

Before you take this medicine: the information on this page is general and may not cover your personal circumstances. Read the label supplied with your medicine and ask a pharmacist or doctor if you are unsure, especially if you are pregnant, breastfeeding, taking other medicines or managing a long-term condition.
General medicine information Consumer-friendly language Source: Drugs.com

Content is provided for education and is not medical advice. See our medical disclaimer. Source page medically reviewed by Carmen Pope, Senior Medical Editor, B. Pharm on September 16, 2026.