Kesimpta (Ofatumumab) - Subcutaneous

What Is Kesimpta?

Kesimpta (ofatumumab) is an injectable medication used to treat relapsing multiple sclerosis (MS) in adults. MS develops when the B cells of the immune system begin to cause inflammation to attack and kill the covering of the nerves in the brain. Kesimpta is an antibody that works by targeting the B cells so that they cannot continue this attack.

Kesimpta is available as a subcutaneous (under the skin) injection in either a single-dose prefilled Sensoready pen or a single-dose prefilled syringe.

Drug Facts

Generic Name: Ofatumumab

Brand Name(s): Kesimpta

Drug Availability: Prescription

Therapeutic Classification: Antineoplastic agent

Available Generically: No

Controlled Substance: No

Administration Route: Subcutaneous injection

Active Ingredient: Ofatumumab

Dosage Form(s): Solution

What Is Kesimpta Used For?

The Food and Drug Administration (FDA) approved Kesimpta to treat adults with relapsing forms of MS, including:

  • Clinically isolated syndrome
  • Relapsing-remitting disease
  • Active secondary progressive disease

It targets a protein on the outside of B cells, called CD20.

How to Take Kesimpta

When starting treatment with Kesimpta, the first doses are given once a week for three weeks, and then change to once every four weeks. It is given through the Sensoready pen or prefilled syringe.

Sensoready Pen

Before using the Kesimpta Sensoready pen, remove it from the refrigerator 15 to 30 minutes before using it. Evaluate the pen to ensure the medication isn't expired and the liquid inside is clear or slightly cloudy.

The front of the thighs is the recommended injection site, although the lower half of the abdomen (stomach) can be used as well. If administering into the abdomen, make sure you inject at least 2 inches away from the navel.

After washing your hands, clean the injection site of the skin with an alcohol wipe and allow it to dry. When ready to inject, remove the cap from the Kesimpta pen, and discard it.

To administer the pen:

  • Hold the pen at a 90-degree angle from the skin where it will be injected.
  • Press the pen against the clean skin firmly.
  • You will hear a click, meaning the injection has started.
  • You will hear a second click when it has almost finished.
  • If the green indicator on the pen is now fully visible and is no longer moving, the medication has been given and the pen can be removed from the skin.

After use, place the Kesimpta pen into a disposable sharps container, not the trash.

Prefilled Syringe

Like the pen, remove the prefilled syringe from the refrigerator 15 to 30 minutes before use. Look closely at the syringe to make sure the medication is not expired and that the liquid inside is clear or slightly cloudy.

It is recommended to inject the prefilled syringe into the front of the thigh. You can also inject into the lower half of the abdomen, at least 2 inches away from the navel. Before injecting, wash your hands and clean the injection site of the skin with an alcohol wipe and allow it to dry. Once you are ready to inject, remove the cap from the prefilled syringe, and discard it.

To administer the syringe:

  • Using your free hand, pinch the area of the skin that will be injected
  • Inject the needle at a 45-degree angle into the skin
  • Once the needle is all of the way into the skin, push down the plunger completely.
  • Continue to push the plunger for five seconds and then wait another five seconds before removing the needle.
  • Once the plunger is released, a needle cover will automatically release, covering the needle for safe disposal. The syringe should be placed in a sharps container and not thrown into the trash.


Kesimpta should be stored in the refrigerator, and removed only a few minutes before being used.

How Long Does Kesimpta Take to Work?

Although it can begin working quickly after an injection, it can take a few months of therapy to have any noticeable improvement in symptoms of relapsing multiple sclerosis.

What Are the Side Effects of Kesimpta?

This is not a complete list of side effects and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your pharmacist or a healthcare provider. You may report side effects to the FDA at or 800-FDA-1088.

Common Side Effects 

The most common side effects from Kesimpta include:

  • Redness, swelling, or itching at the injection site
  • Upper respiratory tract infection
  • Headache
  • Fever, chills, or muscle pain
  • Low immunoglobulin levels

Severe Side Effects 

Call your healthcare provider right away if you have serious side effects. Call 911 if your symptoms feel life-threatening or if you think you’re having a medical emergency. Serious side effects and their symptoms can include the following.

  • Serious bacterial, viral, and fungal infections
  • Reactivation of previous hepatitis B infection
  • Progressive multifocal leukoencephalopathy (PML): A viral infection in the brain

Long-Term Side Effects 

If any of the severe side effects occur, it is possible for them to become long-term effects.

Report Side Effects

Kesimpta may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your healthcare provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

Dosage: How Much Kesimpta Should I Take?

Drug Content Provided and Reviewed by IBM Micromedex®

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For injection dosage form (prefilled syringe or pen):
    • For multiple sclerosis (MS):
      • Adults—At first, 20 milligrams (mg) injected under the skin at Weeks 0, 1, and 2. Followed by 20 mg once a month starting at Week 4.
      • Children—Use and dose must be determined by your doctor.


There are no recommended dose modifications for any reason.

Missed Dose

If a dose is missed, it should be taken as soon as possible and then continued on the regular schedule.

Overdose: What Happens If I Take Too Much Kesimpta?

If too much Kesimpta is taken, notify the prescribing medical provider immediately for further instructions. 

What Happens If I Overdose on Kesimpta?

If you think you or someone else may have overdosed on Kesimpta, call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses or isn't breathing after taking Kesimpta, call 911 immediately.


Drug Content Provided and Reviewed by IBM Micromedex®

It is very important that your doctor check your progress at regular visits to make sure this medicine is working properly and to check for unwanted effects. Blood and urine tests may be needed to check for unwanted effects.

Using this medicine while you are pregnant can harm your unborn baby. Use an effective form of birth control to keep from getting pregnant during treatment and for at least 6 months after the last dose of this medicine. If you think you have become pregnant while using the medicine, tell your doctor right away.

This medicine may cause chest pain, fever, chills, itching, hives, flushing of the face, rash, dizziness, fainting, or lightheadedness, trouble breathing, or swelling of the face, tongue, and throat within a few hours after you receive it. Check with your doctor or nurse right away if you have any of these symptoms.

This medicine may cause a serious type of reaction called tumor lysis syndrome. Your doctor may give you a medicine to help prevent this. Call your doctor right away if you have a decrease or change in urine amount, joint pain, stiffness, or swelling, lower back, side, or stomach pain, a rapid weight gain, swelling of the feet or lower legs, or unusual tiredness or weakness.

Ofatumumab can temporarily lower the number of white blood cells in your blood, increasing the chance of getting an infection. It can also lower the number of platelets, which are necessary for proper blood clotting. If this occurs, there are certain precautions you can take, especially when your blood count is low, to reduce the risk of infection or bleeding:

  • If you can, avoid people with infections. Check with your doctor immediately if you think you are getting an infection or if you get a fever or chills, cough or hoarseness, lower back or side pain, or painful or difficult urination.
  • Check with your doctor immediately if you notice any unusual bleeding or bruising, black, tarry stools, blood in the urine or stools, or pinpoint red spots on your skin.
  • Be careful when using a regular toothbrush, dental floss, or toothpick. Your medical doctor, dentist, or nurse may recommend other ways to clean your teeth and gums. Check with your medical doctor before having any dental work done.
  • Do not touch your eyes or the inside of your nose unless you have just washed your hands and have not touched anything else in the meantime.
  • Be careful not to cut yourself when you are using sharp objects such as a safety razor or fingernail or toenail cutters.
  • Avoid contact sports or other situations where bruising or injury could occur.

This medicine may increase your risk of developing a serious and rare brain infection called progressive multifocal leukoencephalopathy (PML). Check with your doctor right away if you have vision changes, loss of coordination, clumsiness, memory loss, difficulty speaking or understanding what others say, and weakness in the legs.

This medicine may cause hepatitis B virus reactivation. Check with your doctor right away if you have any symptoms of liver problems, including yellow skin or eyes, dark brown-colored urine, right-sided stomach pain, fever, or severe tiredness.

Do not have any live vaccines (immunizations) while you are being treated with ofatumumab injection. You should have completed any needed immunizations at least 4 weeks for live or live-attenuated vaccines and at least 2 weeks for non-live (inactivated) vaccines before starting treatment with this medicine. Check with your doctor before having any vaccines.

Do not take other medicines unless thy have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

What Are Reasons I Shouldn’t Take Kesimpta? 

You should not use Kesimpta:

  • At least four weeks after getting a live vaccine or two weeks after getting an inactivated vaccine
  • If you are pregnant or trying to become pregnant, as it can cause harm to the fetus
  • If you have an active hepatitis B infection

What Other Medications Interact With Kesimpta? 

There are no specific interactions with other medications. However, other medications which potentially suppress the immune system may need to be avoided to reduce the risk of developing an infection.

What Medications Are Similar?

There are other medications that work similarly to Kesimpta for relapsing MS, but target different cells:

  • Lemtrada (alemtuzumab) is an infusion used for relapsing MS and targets the CD 52 protein on T-cells and B cells.
  • Tysabri (matalizumab) is an infusion used to treat relapsing MS in addition to Crohn’s disease. It works by blocking the ability of cells of the immune system to get into the brain to cause inflammation.
  • Ocrevus (ocrelizumab) works similarly to Kesimpta by targeting the CD 20 protein on B cells and is used to treat primary and relapsing MS.

Frequently Asked Questions

  • What is Kesimpta used for?

    Kesimpta is used to treat relapsing MS, a disease in which the immune system breaks down the coating on the nerves in the brain. This can lead to various symptoms, including vision changes, loss of coordination, weakness, and pain.

  • How does Kesimpta work?

    Kesimpta works by destroying the B cells in the lymph nodes, which are responsible for causing the inflammation and damage to the nerve coating in the brain.

  • What are the side effects of Kesimpta?

    The most common side effects of Kesmpita include headache, injection site reactions, and upper respiratory infection.

  • How to stop taking Kesimpta?

    Kesimpta should not be stopped unless directed by the ordering healthcare provider. 

How Can I Stay Healthy While Taking Kesimpta?

When taking Kesimpta, staying organized to know when the injection is due is important. Remember to take your medication on schedule in order to get the most benefit from your treatment plan.

Be sure to notify your healthcare provider of any side effects that you may experience. They can help you manage any side effects that you may experience.

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and not intended as a replacement for medical advice, diagnosis, or treatment from a healthcare provider. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Food and Drug Administration. Kesimpta label.

  2. Food and Drug Administration. Lemtrada label.

  3. Food and Drug Administration. Tysabri label.

  4. Food and Drug Administration. Ocrevus label.

By Julie Scott, MSN, ANP-BC, AOCNP
Julie is an Adult Nurse Practitioner with oncology certification and a healthcare freelance writer with an interest in educating patients and the healthcare community.