If you have multiple sclerosis (MS), your doctor may prescribe Kesimpta for you.

It’s a prescription drug that’s used to treat the following conditions in adults:

To learn more about these conditions, see “What is Kesimpta used to treat?” below.

Kesimpta basics

Kesimpta comes as a liquid solution that’s given as an injection under your skin.

You’ll inject the drug using single-dose syringes or pens.

Kesimpta contains the drug ofatumumab, which is a biologic medication. A biologic is made from parts of living organisms.

Kesimpta isn’t available in a biosimilar form. (Biosimilars are like generic drugs. But unlike generics, which are made for nonbiologic drugs, biosimilars are made for biologic drugs.)

Instead, ofatumumab is available only as the brand-name drug Kesimpta.

Read on to learn about how Kesimpta is given, as well as its uses, side effects, and more.

Below are answers to some common questions about Kesimpta.

What should I know about Kesimpta vs. Ocrevus, Tysabri, and Tecfidera?

Kesimpta is used to treat certain types of multiple sclerosis (MS). (For details on the drug’s uses, see “What is Kesimpta used to treat?” below.)

You may wonder how Kesimpta compares with other drugs that treat MS, such as:

All the drugs listed above help stop your immune system from attacking the covering that protects your brain and spinal cord.

Kesimpta, Ocrevus, and Tysabri are given as injections. Tecfidera comes as capsules you take by mouth.

For more details about how Kesimpta compares with these medications, talk with your doctor or pharmacist.

Are there reviews available from people who’ve taken Kesimpta?

Kesimpta has been found effective for treating certain types of MS. (For details on the drug’s uses, see “What is Kesimpta used to treat?” below.)

The manufacturer of this drug doesn’t provide reviews from people who’ve taken its drug. But you can learn more about Kesimpta’s studies by visiting the manufacturer’s site. Or, you can read the drug’s prescribing information.

For more information about what to expect with Kesimpta treatment, talk with your doctor or pharmacist.

How does Kesimpta work?

MS, which Kesimpta treats, is a condition that causes your immune system to attack the covering that protects your brain and spinal cord. Your spinal cord contains neurons (nerve cells) that help your brain communicate with the rest of your body.

When this protective covering is damaged, your brain has trouble communicating with the rest of your body.

Kesimpta’s mechanism of action (how it works) to treat MS isn’t completely known. The drug is thought to lessen the activity of your immune system. By lessening your immune system’s activity, Kesimpta may keep it from attacking the protective covering around your brain and spinal cord.

If you have more questions about how Kesimpta works, talk with your doctor or pharmacist.

Does Kesimpta cause weight gain?

Weight gain wasn’t a side effect reported in studies of Kesimpta. But weight changes can be symptoms of MS, which Kesimpta treats.

If you’re concerned about weight gain while taking Kesimpta, talk with your doctor. They can suggest healthy ways to manage weight changes that may happen with MS.

Like most drugs, Kesimpta may cause mild or serious side effects. The lists below describe some of the more common side effects that Kesimpta may cause. These lists don’t include all possible side effects.

Keep in mind that side effects of a drug can depend on:

  • your age
  • other health conditions you have
  • other medications you take

Your doctor or pharmacist can tell you more about the potential side effects of Kesimpta. They can also suggest ways to help reduce side effects.

Mild side effects

Here’s a short list of some of the mild side effects that Kesimpta can cause. To learn about other mild side effects, talk with your doctor or pharmacist or read Kesimpta’s medication guide.

Mild side effects of Kesimpta that have been reported include:

Mild side effects of many drugs may go away within a few days or a couple of weeks. But if they become bothersome, talk with your doctor or pharmacist.

* For more information about this side effect, see the “Side effect focus” section below.

Serious side effects

Serious side effects from Kesimpta can occur, but they aren’t common. If you have serious side effects from Kesimpta, call your doctor right away. But if you think you’re having a medical emergency, call 911 or your local emergency number.

Serious side effects of Kesimpta that have been reported include:

* For more information about this side effect, see the “Side effect focus” section below.

Side effect focus

Learn more about some of the side effects Kesimpta may cause.

Reactions at your injection sites

You might have certain reactions around the site of your Kesimpta injections. These side effects were common in studies of the drug.

You’ll typically inject Kesimpta into your lower belly, your upper arm, or the front of your thigh. You may have reactions around these injection sites after any Kesimpta injection. But your risk of these reactions is highest after you receive your first injection of the drug.

Examples of possible reactions you may have at your injection sites include:

  • pain
  • itching
  • redness of the skin or deepening of skin color
  • swelling

What might help

If you have reactions at your Kesimpta injection sites, talk with your doctor. They can recommend ways to help ease your symptoms.

Infections

Kesimpta may weaken your immune system, which can increase your risk of mild and serious infections. Mild infections were more common than serious infections in studies of the drug.

Examples of mild infections that can happen with Kesimpta include:

Symptoms of infection can vary depending on the exact infection you have. Possible symptoms include chills, cough, fever, and painful urination.

Kesimpta may also cause a rare but serious brain infection called PML.

What might help

Tell your doctor right away if you have any symptoms of infection while using Kesimpta. If you have an infection, they may stop your Kesimpta treatment until the infection is treated.

Back pain

You may have back pain while using Kesimpta. This was one of the most common side effects in studies of the drug.

Keep in mind that back pain can be a symptom of a UTI. This is another possible side effect of Kesimpta. For details about your risk of infections with Kesimpta, see “Infections” just above.

What might help

If you have bothersome back pain while using Kesimpta, talk with your doctor. They may check you for other signs of a UTI. Your doctor can also suggest ways to relieve this side effect.

Allergic reaction

It’s not known from studies of Kesimpta how often allergic reactions occur. But, as with most drugs, these reactions are possible.

Symptoms of a mild allergic reaction can include:

  • skin rash
  • itchiness
  • flushing (temporary warmth, redness, or deepening of skin color)

A more severe allergic reaction is rare but possible. Symptoms of a severe allergic reaction can include swelling under your skin, typically in your eyelids, lips, hands, or feet. They can also include swelling of your tongue, mouth, or throat, which can cause trouble breathing.

Call your doctor right away if you have an allergic reaction to Kesimpta. But if you think you’re having a medical emergency, call 911 or your local emergency number.

Costs of prescription drugs can vary depending on many factors. These factors include what your insurance plan covers and which pharmacy you use. To find current prices for Kesimpta in your area, visit GoodRx.com.

If you have questions about how to pay for your prescription, talk with your doctor or pharmacist. You can also visit the Kesimpta manufacturer’s website to see if it offers any support options.

If you have multiple sclerosis (MS), your doctor may prescribe Kesimpta for you.

It’s a prescription drug that’s used to treat the following conditions in adults:

  • Clinically isolated syndrome (CIS). CIS is a single episode of MS symptoms that lasts at least 24 hours. CIS is often the first sign of MS, but it doesn’t always lead to MS.
  • Relapsing-remitting MS (RRMS). RRMS is repeated cycles of MS relapses (periods of new or worsening symptoms) followed by remissions (periods of no symptoms). Relapse episodes may last for many days or months, while remission episodes can last for many years.
  • Active secondary-progressive MS (SPMS). Active SPMS usually develops after RRMS. Over time, people with RRMS may stop having episodes of remission while their MS symptoms keep getting worse. When this happens, a doctor will usually diagnose active SPMS.

With MS, your immune system attacks the covering that protects your brain and spinal cord. Your spinal cord contains neurons (nerve cells) that help your brain communicate with the rest of your body.

When this protective covering is damaged, your brain can’t communicate well with the rest of your body. This is what causes many of the symptoms related to MS, such as:

How Kesimpta treats MS isn’t completely known. The drug is thought to lessen the activity of your immune system.

Your doctor will recommend the dosage of Kesimpta that’s right for you. Below are commonly used dosages, but always take the dosage your doctor prescribes.

Forms

Kesimpta comes as a liquid solution that’s given as an injection under your skin.

It’s available in two forms:

  • a single-dose, prefilled syringe
  • a single-dose, prefilled injection pen

Your doctor can show you how to give yourself Kesimpta injections. And they can advise which form of Kesimpta is best for you.

Recommended dosage

The usual dosage of Kesimpta is one injection into your lower belly, your upper arm, or the front of your thigh.

Your doctor may start by prescribing loading doses of Kesimpta for you. Loading doses are meant to get a high level of the drug into your body. With Kesimpta, this means getting more injections during the first month. This helps the drug start working quickly to treat your condition.

You may receive your first few injections of Kesimpta from your doctor. You’ll receive your first injection followed by a second injection 1 week later. Then, you’ll get your third injection 2 weeks after the first injection. You won’t have any injections during week 3. Then, you’ll get one injection of Kesimpta at week 4.

You’ll take your next injection at week 8. And you’ll continue using only one injection of Kesimpta each month after that.

After your first few doses, you may start giving Kesimpta injections to yourself at home. Your doctor will show you how to do this.

Questions about Kesimpta’s dosage

Below are answers to a few common questions about Kesimpta’s dosage.

  • What if I miss a dose of Kesimpta? This depends on where you are in your injection schedule. If you miss a dose of Kesimpta in your first 4 weeks of treatment, talk with your doctor. They’ll tell you what to do about your missed dose. But if you miss one of your monthly injections of Kesimpta, inject your missed dose as soon as you remember. Then, your next dose should be taken 1 month from the date you injected your missed dose.
    • For example, if you took your missed dose on the 10th of the month, you’ll take all of your upcoming doses on the 10th of each month. If you have any questions about a missed dose, talk with your doctor.
  • Will I need to use Kesimpta long term? Yes, Kesimpta is meant to be used long term. But your doctor will tell you exactly how long you should use the drug.
  • How long does Kesimpta take to work? It will likely take several weeks after your first dose of Kesimpta for you to notice your symptoms easing.
  • Should I take Kesimpta doses with food? You can give yourself Kesimpta injections with or without having eaten.

When considering Kesimpta treatment, it’s important to talk with your doctor about:

  • your overall health
  • any medical conditions you have
  • other medications you’re taking

Below are some things to consider before taking Kesimpta.

Interactions

Taking medications, vaccines, foods, and other things with a certain drug can affect how the drug works. These effects are called interactions.

Before taking Kesimpta, be sure to tell your doctor about all medications you take, including prescription and over-the-counter types. Also, describe any vitamins, herbs, or supplements you use. Your doctor or pharmacist can tell you about any interactions these items may cause with Kesimpta.

Interactions with drugs or supplements

Kesimpta can interact with drugs that weaken your immune system, such as corticosteroids. Prednisone (Rayos) is an example of a corticosteroid.

There are other drugs that may interact with Kesimpta. Your doctor or pharmacist can tell you more about these interactions and any others that may occur with use of Kesimpta.

Other interactions

You should avoid getting vaccines while using Kesimpta. This includes live (active) vaccines and non-live (inactive) vaccines.

Live vaccines

Live vaccines contain a weakened form of the bacterium or virus that the vaccine helps prevent an infection from.

Live vaccines don’t usually cause an infection in a person with a healthy immune system. But in a person with a weakened immune system, including someone using Kesimpta, a live vaccine could cause infection.

Below are a few examples of live vaccines:

Before starting Kesimpta treatment, talk with your doctor about whether you’re up to date on all recommended vaccines.

They’ll likely recommend that you don’t get a live vaccine for at least 4 weeks before you start using Kesimpta. They’ll also suggest that you avoid live vaccines while using the drug and for a while after your last dose.

Talk with your doctor about when it’s safe for you to get live vaccines after you’ve stopped Kesimpta treatment.

Non-live vaccines

Non-live vaccines don’t contain any live bacteria or viruses. Still, Kesimpta can make non-live vaccines less effective for you.

Examples of non-live vaccines include:

Before starting Kesimpta treatment, talk with your doctor about whether you’re up to date on all recommended vaccines.

In most cases, your doctor will suggest that you avoid non-live vaccines for at least 2 weeks before you start using Kesimpta. They’ll also likely suggest that you avoid non-live vaccines during treatment with this drug and for a while after your last dose.

Talk with your doctor about when it’s safe for you to get non-live vaccines after you’ve stopped Kesimpta treatment.

Warnings

Kesimpta may not be right for you if you have certain medical conditions or other factors that affect your health. Talk with your doctor about your health history before you take Kesimpta. Factors to consider include those in the list below.

  • Active infection. Before starting Kesimpta treatment, tell your doctor about any infections you have. Your body may not be able to fight infections as well after you start taking the drug. Your doctor will want to make sure that any active infections are treated before you take Kesimpta.
  • Hepatitis B virus (HBV). You shouldn’t use Kesimpta if you have active HBV. (“Active” means that you have a detectable amount of the virus in your body.) Before you start using Kesimpta, your doctor will order an HBV test for you. If you have HBV in your system, your doctor will likely treat the infection before you start using the drug.
  • Recent vaccination. Before you start Kesimpta treatment, tell your doctor if you’ve recently had any vaccines. They may have you wait to start using Kesimpta until several weeks after your vaccine was given. For details about using Kesimpta with vaccines, see the “Interactions” section just above.
  • Allergic reaction. If you’ve had an allergic reaction to Kesimpta or any of its ingredients, you should not take Kesimpta. Ask your doctor what other medications are better options for you.

Kesimpta and alcohol

There aren’t any known issues with drinking alcohol while using Kesimpta. But before you start treatment, talk with your doctor about the amount of alcohol that’s safe for you to drink while using this drug.

Pregnancy and breastfeeding

It may not be safe to use Kesimpta while pregnant.

To help prevent pregnancy, females* should use an effective form of birth control while taking Kesimpta. And they should continue using birth control for at least 6 months after their last dose.

The manufacturer of Kesimpta hasn’t provided birth control recommendations for males* who use the drug. If you’re a male taking Kesimpta, talk with your doctor about your birth control options.

It isn’t known if Kesimpta is safe to use during breastfeeding. Talk with your doctor about the risks and benefits of using Kesimpta during this time.

* In this article, we use the terms “male” and “female” to refer to someone’s sex assigned at birth. For information about the difference between sex and gender, see this article.

Your doctor will explain how you should inject Kesimpta. They will also explain how much to take and how often. Be sure to follow your doctor’s instructions.

Taking Kesimpta

Kesimpta comes as a liquid solution that’s given as an injection under your skin.

Kesimpta is available in two forms:

  • a single-dose, prefilled syringe
  • a single-dose, prefilled injection pen

Your doctor can advise which form of Kesimpta is best for you.

You’ll inject Kesimpta into your lower belly, your upper arm, or the front of your thigh.

Your doctor can show you how to give yourself Kesimpta injections. You can also visit the drug manufacturer’s website for more information on how to self-inject Kesimpta.

Questions for your doctor

You may have questions about Kesimpta and your treatment plan. It’s important to discuss all your concerns with your doctor.

Here are a few tips that might help guide your discussion:

  • Before your appointment, write down questions such as:
    • How will Kesimpta affect my body, mood, or lifestyle?
  • Bring someone with you to your appointment if doing so will help you feel more comfortable.
  • If you don’t understand something related to your condition or treatment, ask your doctor to explain it to you.

Remember, your doctor and other healthcare professionals are available to help you. And they want you to get the best care possible. So, don’t be afraid to ask questions or offer feedback on your treatment.

Don’t take more Kesimpta than your doctor prescribes. For some drugs, using more than this can lead to serious side effects.

What to do in case you take too much Kesimpta

Call your doctor if you think you’ve taken too much Kesimpta. You can also call 800-222-1222 to reach the American Association of Poison Control Centers, or you can use its online resource. But if you have severe symptoms, immediately call 911 (or your local emergency number) or go to the nearest emergency room.

If you have multiple sclerosis (MS), your doctor may prescribe Kesimpta for you. (For details on the drug’s uses, see “What is Kesimpta used to treat?” above.)

Here are a few questions you may want to ask them about this drug:

  • Will my MS symptoms come back after I stop using Kesimpta?
  • How is this drug different from other MS treatments?
  • Can I use Kesimpta with other MS treatments?
  • What other MS treatment options might work well for me?

There are other treatment options available for MS. You can view this article to learn more about them. Be sure to discuss the best treatment option for you with your doctor or pharmacist.

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Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.