Kesimpta is a brand-name prescription medication. It’s FDA-approved to treat certain forms of multiple sclerosis (MS) in adults.

MS is a condition that affects your brain and spinal cord. It can cause symptoms such as vision changes, difficulty walking, and fatigue (lack of energy).

To be specific, Kesimpta is approved to treat:

  • Relapsing-remitting MS. Withrelapsing-remitting MS (RRMS), the condition wavers between stages of remission and relapse. During remission, you have few or no symptoms. During a relapse, symptoms flare up.
  • Active secondary progressive MS. With secondary progressive MS (SPMS), there are no periods of remission. Symptoms continue to worsen over time.
  • Clinically isolated syndrome. With clinically isolated syndrome (CIS), you experience symptoms similar to those of MS in an episode lasting 24 hours or more. In some cases, CIS may become MS, but in other cases, it may not.

Drug details

The active drug ingredient in Kesimpta is ofatumumab. Kesimpta belongs to a group of medications called monoclonal antibodies.

Kesimpta comes as a liquid solution that’s given as a subcutaneous injection (an injection given just under your skin). The drug comes in two forms: a single-dose prefilled Sensoready pen and a single-dose prefilled syringe. Your doctor can help determine which form is right for you.

Both forms contain 20 milligrams (mg) of Kesimpta in 0.4 milliliters (mL) of liquid solution. To learn how often Kesimpta is typically used, see the “Kesimpta dosage” section below.

Effectiveness

For information about the effectiveness of Kesimpta, see the “Kesimpta uses” section below.

Kesimpta is available only as a brand-name medication. It’s a biologic drug, which is a medication made from living cells.

Because it’s not possible to copy living cells in a lab, biologic drugs don’t have generic forms. Instead, they may have a biosimilar form. A biosimilar form is a drug that has been shown to be just as safe and effective as the original biologic form. Kesimpta is not currently available in biosimilar form.

Biosimilar drugs usually cost less than brand-name biologic drugs.

Kesimpta can cause mild or serious side effects. The following lists contain some of the key side effects that may occur while using Kesimpta. These lists don’t include all possible side effects.

For more information about the possible side effects of Kesimpta, talk with your doctor or pharmacist. They can give you tips on how to deal with any side effects that may be concerning or bothersome.

Note: The Food and Drug Administration (FDA) tracks side effects of drugs it has approved. If you would like to notify the FDA about a side effect you’ve had with Kesimpta, you can do so through MedWatch.

Mild side effects

Mild side effects* of Kesimpta can include:

Most of these side effects may go away within a few days or a couple of weeks. But if they become more severe or don’t go away, talk with your doctor or pharmacist.

* This is a partial list of mild side effects from Kesimpta. To learn about other mild side effects, talk with your doctor or pharmacist, or view Kesimpta’s medication guide.
† For more information about this side effect, see “Side effect details” below.

Serious side effects

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

Serious side effects and their symptoms can include:

* For more information about this side effect, see “Side effect details” below.

Side effect details

Here’s some detail on certain side effects this drug may cause.

Infections

Kesimpta may increase the risk of developing an infection. Many infections that were reported in people using Kesimpta included colds, sinus infections, and urinary tract infections (UTIs).

Mild infections were very common in people using Kesimpta. Depending on the type of mild infection you have, symptoms may include a runny or stuffy nose, cough, sore throat, or painful urination.

For information on a serious brain infection, see “Progressive multifocal leukoencephalopathy” below.

To find out how often infections occurred in clinical studies, see the drug’s prescribing information. If you have any additional concerns about infections that may occur when you’re using Kesimpta, talk with your doctor or pharmacist. They may be able to recommend ways to boost your immune system to prevent infections from occurring.

Injection site reactions

Injection site reactions may occur with Kesimpta use. These are reactions around the area where Kesimpta was injected and can include:

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

These reactions are some of the most common side effects that may occur in people using Kesimpta. In clinical trials, all injection site reactions were mild or moderate. There were no cases of severe injection site reactions.

To find out how often injection site reactions occurred in clinical studies, see the drug’s prescribing information. If you have any additional concerns about injection site reactions, talk with your doctor or pharmacist. They may be able to recommend different injection techniques or suggest using ice after your dose to help prevent the reactions from occurring.

Hepatitis B reactivation

If a person has had hepatitis B, the virus that causes hepatitis B could become active again. This is known as hepatitis B reactivation. Symptoms may include diarrhea, abdomen (belly) pain, and jaundice (yellowing of the skin or the whites of eyes).

Hepatitis B reactivation didn’t occur in clinical trials of people with multiple sclerosis (MS) who used Kesimpta. But this side effect did occur in clinical trials of people with chronic lymphocytic leukemia who used ofatumumab (Arzerra). Ofatumumab is the active drug ingredient in both Arzerra and Kesimpta.

The Food and Drug Administration (FDA) often requires a drug’s prescribing information to include potential serious risks. This is no matter how rare the side effect may be or whether there’s a known link between the side effect and the medication.

Because Kesimpta contains ofatumumab, hepatitis B reactivation is included in Kesimpta’s prescribing information.

If you have any questions about hepatitis B reactivation, talk with your doctor.

Progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is a rare but very serious brain infection. Symptoms may include difficulty walking or speaking, changes in personality, and facial drooping.

PML didn’t occur in clinical trials of people with MS who used Kesimpta. But this side effect did occur in clinical trials of people with chronic lymphocytic leukemia who used ofatumumab (Arzerra). Ofatumumab is the active drug ingredient in both Arzerra and Kesimpta.

The FDA often requires a drug’s prescribing information to include potential serious risks. This is no matter how rare the side effect may be or whether there’s a known link between the side effect and the medication.

Because Kesimpta contains ofatumumab, PML is included in Kesimpta’s prescribing information.

If you have any questions about PML, talk with your doctor.

Allergic reaction

As with most drugs, some people can have an allergic reaction after using Kesimpta. But it’s not known how often allergic reactions may have occurred in people using Kesimpta in clinical trials.

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
  • swelling of your tongue, mouth, or throat
  • trouble breathing

Call your doctor right away if you have an allergic reaction to Kesimpta, as the reaction could become severe. Call 911 or your local emergency number if your symptoms feel life threatening or if you think you’re having a medical emergency.

As with all medications, the cost of Kesimpta can vary. For instance, the drug’s cost per month and cost per year may differ between people. The actual price you’ll pay depends on your insurance plan, your location, and the pharmacy you use.

Keep in mind that you may be able to get a 90-day supply of Kesimpta. If approved by your insurance company, getting a 90-day supply of the drug could reduce your number of trips to the pharmacy and help lower the cost. If you’re interested in this option, check with your doctor or your insurance company.

It’s important to note that you may have to get Kesimpta at a specialty pharmacy. This type of pharmacy is authorized to carry specialty medications. These are drugs that may be expensive or may require help from healthcare professionals to be used safely and effectively.

Before approving coverage for Kesimpta, your insurance company may require you to get prior authorization. This means that your doctor and insurance company will need to communicate about your prescription before the insurance company will cover the drug. The insurance company will review the prior authorization request and decide if the drug will be covered.

If you’re not sure if you’ll need to get prior authorization for Kesimpta, contact your insurance company.

Financial and insurance assistance

If you need financial support to pay for Kesimpta, or if you need help understanding your insurance coverage, help is available.

Novartis Pharmaceuticals, the manufacturer of Kesimpta, offers ways to help lower the cost of the drug. For more information and to find out if you’re eligible for support, call 800-721-8909 or visit the drug website.

Mail-order pharmacies

Kesimpta may be available through a mail-order pharmacy. Using this service may help lower the drug’s cost and allow you to get your medication without leaving home.

If recommended by your doctor, you may be able to receive a 90-day supply of Kesimpta, so there’s less concern about running out of the medication. If you’re interested in this option, check with your doctor and your insurance company. Some Medicare plans may help cover the cost of mail-order medications.

If you don’t have insurance, you can ask your doctor or pharmacist about online pharmacy options.

Generic or biosimilar version

Kesimpta is available only as a brand-name medication. It’s a biologic drug, which is a medication made from living cells.

Because it’s not possible to copy living cells in a lab, biologic drugs don’t have generic forms. Instead, they may have a biosimilar form. A biosimilar form is a drug that has been shown to be just as safe and effective as the original biologic form. Kesimpta is not currently available in biosimilar form.

Biosimilar drugs usually cost less than brand-name biologic drugs.

Other drugs are available that can treat multiple sclerosis (MS) and clinically isolated syndrome (CIS). To learn about these conditions, see the “Kesimpta for MS” section below.

Some medications may be a better fit for you than others. If you’re interested in finding an alternative to Kesimpta, talk with your doctor. They can tell you about other medications that may work well for you.

Note: Some of the drugs listed here are used off-label to treat these specific conditions. Off-label drug use is when a drug approved by the Food and Drug Administration (FDA) for one purpose is used for a different purpose.

Examples of other drugs that may be used to treat MS and CIS include:

Here are answers to some frequently asked questions about Kesimpta.

What should I know about Kesimpta vs. Ocrevus?

Like Kesimpta, Ocrevus is approved to treat certain forms of multiple sclerosis (MS) and clinically isolated syndrome (CIS).

Kesimpta is given as a subcutaneous injection (an injection under your skin). Ocrevus, on the other hand, is given by intravenous (IV) infusion. (This is an injection into a vein over a period of time.)

If you’d like to know more about how these drugs compare, talk with your doctor. They can tell you about possible side effects of each drug. And they can recommend if one option may be better for you.

Does Kesimpta cause hair loss or weight gain?

No, these weren’t reported as side effects in clinical trials of the drug.

Symptoms of multiple sclerosis (MS), the condition that Kesimpta is used to treat, may lead to weight changes. For example, having trouble walking or exercising may lead to weight gain.

It’s possible that hair loss can be a side effect of other medications used to treat MS. This includes the drug methotrexate.

Keep in mind that stress can also contribute to both hair loss and weight changes.

If you’re concerned about hair loss or weight gain while you’re taking Kesimpta, tell your doctor. They can suggest ways to help you manage these symptoms.

Will I need to have lab tests done while I’m using Kesimpta?

Yes, you’ll need to have blood tests done while you’re using Kesimpta. Before you start treatment, your doctor will order blood tests to check for infections, such as hepatitis B. They’ll also look at your immunoglobulin levels, which help show how well your immune system is working. (An immunoglobulin is a type of protein.)

Your doctor will continue to monitor your immunoglobulin levels throughout your Kesimpta treatment. If your levels become too low, they may have you stop using the drug. Low immunoglobulin levels may cause you to develop infections easier than usual, which may be serious.

Before you start using Kesimpta, talk with your doctor about blood tests that you need.

Is Kesimpta an immunosuppressant?

Yes, Kesimpta is a type of drug called an immunosuppressant, which is meant to weaken the immune system. It’s believed that Kesimpta works by decreasing the activity of your immune system. This helps ease the symptoms of multiple sclerosis (MS). For more information on how Kesimpta works, see the “How Kesimpta works” section above.

If I used Kesimpta during pregnancy, can my child receive vaccines on schedule?

It depends. If you use Kesimpta during pregnancy, the drug may affect both your immune system and that of your developing child. Once your child is born, their doctor will order blood tests to see how strong your child’s immune system is.

Your child shouldn’t receive any live vaccines until their immune system is healthy enough. Live vaccines contain live but weakened pieces of the virus or bacterium they’re meant to defend against. When an immune system is strong, live vaccines usually won’t cause infection. But live vaccines may cause infection if an immune system is weak.

Once your child is born, they should be able to receive non-live vaccines on schedule. Non-live vaccines don’t contain live viruses or bacteria. So they aren’t likely to cause symptoms of the illness the vaccine is meant to prevent.

However, your child’s doctor may order blood tests to see if the non-live vaccine is working. This is because non-live vaccines require the immune system to be healthy in order to act properly. If your child has a weakened immune system, non-live vaccines may not work as well as usual.

For information on which vaccines are live and which are non-live, see “Live vaccines” and “Non-live vaccines” in the “Kesimpta interactions” section above. If you have any questions about your child’s vaccine schedule, be sure to talk with their doctor.

The Food and Drug Administration (FDA) approves prescription drugs such as Kesimpta to treat certain conditions. A drug’s approved uses are also called its indications.

Kesimpta is FDA-approved to treat certain forms of multiple sclerosis (MS) in adults. To be specific, the drug is approved to treat:

  • Relapsing-remitting MS. Withrelapsing-remitting MS (RRMS), the condition wavers between stages of remission and relapse. During remission, you have few or no symptoms. During a relapse, symptoms flare up.
  • Active secondary progressive MS. With secondary progressive MS (SPMS), there are no periods of remission. Symptoms continue to worsen over time.
  • Clinically isolated syndrome. With clinically isolated syndrome (CIS), you experience symptoms similar to those of MS in an episode lasting 24 hours or more. In some cases, CIS may become MS, but in other cases, it may not.

MS explained

MS is a condition that affects your brain and spinal cord. With MS, your immune system mistakenly attacks the myelin sheath (the covering over your nerves). Your nerves help your brain communicate with the rest of your body. If the myelin sheath doesn’t work properly, your brain can’t communicate easily with the rest of your body. This may lead to the symptoms of MS, including vision changes, difficulty walking, and fatigue (lack of energy).

Effectiveness for MS

Kesimpta has been shown to be an effective treatment option for RRMS, SPMS, and CIS. For additional information on how Kesimpta performed in clinical studies, see the Kesimpta prescribing information.

Kesimpta and children

Kesimpta is approved for use only in adults. At this time, it’s not known if Kesimpta is a safe and effective treatment option for children with MS.

If you’re interested in MS treatments for your child, talk with your doctor.

The following information describes dosages that are commonly used or recommended. However, be sure to use the dosage your doctor prescribes for you. Your doctor will determine the best dosage to fit your needs.

Drug forms and strengths

Kesimpta comes as a liquid solution that’s given as a subcutaneous injection (an injection given just under your skin). The drug comes in two forms:

  • single-dose prefilled Sensoready pen
  • single-dose prefilled syringe

Your doctor can help determine which form is right for you. Kesimpta is available in one strength: 20 milligrams (mg) of the drug in 0.4 milliliters (mL) of liquid solution.

Dosage for MS

Kesimpta is used to treat certain forms of multiple sclerosis (MS) in adults. To be specific, the drug is approved to treat the following:*

For this purpose, the usual dose of Kesimpta is one 20-mg injection into your thigh, abdomen (belly), or the outer part of your upper arm. Your doctor or another healthcare professional will first show you or your caregiver how to properly give a dose of medication. After that, you or your caregiver can inject the doses at home. (For more information on Kesimpta injections, see the “How to use Kesimpta” section below.)

You’ll use Kesimpta more frequently at the beginning of treatment than later on. These starting doses are called loading doses and they’re meant to help start treating your symptoms quickly. Here’s the typical dosing schedule:

  • Week 0: first dose
  • Week 1: second dose
  • Week 2: third dose
  • Week 3: no dose
  • Week 4: fourth dose

After your first four doses, you’ll have a dose of Kesimpta once every month.

* For more information on these conditions, see the “Kesimpta for MS” section above.

What if I miss a dose?

If you miss a dose of Kesimpta during your first 4 weeks of treatment, talk with your doctor or pharmacist. They can advise you on what to do.

If you miss a dose of Kesimpta after your first 4 weeks of treatment, take it as soon as you remember, even if it’s almost time for your next dose. After that, you should continue using Kesimpta once per month.

If you have any questions about when to take your next dose, talk with your doctor or pharmacist.

To help make sure that you don’t miss a dose, try using a medication reminder. This can include setting an alarm or timer on your phone or downloading a reminder app. A kitchen timer can work, too.

Will I need to use this drug long term?

Kesimpta is meant to be used as a long-term treatment. If you and your doctor determine that Kesimpta is safe and effective for you, you’ll likely use it long term.

Kesimpta is used to treat certain forms of multiple sclerosis (MS). MS is a condition in which your immune system is overactive. It mistakenly attacks the myelin sheath (the covering over your nerves). Your nerves help your brain communicate with the rest of your body. If the myelin sheath doesn’t work properly, your brain can’t communicate easily with the rest of your body.

Kesimpta’s mechanism of action (how it works) to treat MS isn’t known exactly. But it’s believed that the drug attaches to a protein called CD20. This protein is on cells in your immune system called lymphocytes. When Kesimpta attaches to lymphocytes, it kills them. Because MS is a condition in which your immune system is overactive, Kesimpta likely works by decreasing the activity of your immune system so that it doesn’t destroy your myelin sheath.

How long does it take to work?

Kesimpta should begin working as soon as you have your first dose. But it may take a few weeks before you notice your symptoms easing. This is because the drug takes some time to relieve your symptoms. For the first few weeks of Kesimpta treatment, you’ll have a dose once weekly. This helps the medication to begin working quickly.

You should use Kesimpta according to your doctor’s or healthcare professional’s instructions.

Kesimpta comes as a liquid solution that’s administered as a subcutaneous injection (an injection given just under your skin). The drug comes in two forms:

  • single-dose prefilled Sensoready pen
  • single-dose prefilled syringe

Your doctor can help determine which form is right for you.

Injection information

Your doctor or another healthcare professional will first show you or your caregiver how to inject the medication. After that, you or your caregiver can inject the doses at home.

You should inject Kesimpta into your thigh, abdomen (belly), or the outer part of your upper arm. Be sure to avoid any areas that have moles, scars, or stretch marks. Also avoid injecting into skin that is bruised, red, hard, or scaly.

For more information on how to inject Kesimpta using the Sensoready pen, see the drug website. You’ll find step-by-step instructions and videos.

After injection

Once you inject a dose of Kesimpta, be sure to discard the pen or syringe that you use. These are for one-time use only and shouldn’t be used again. To learn more about disposal, see the “Kesimpta expiration, storage, and disposal” section below.

When to use

When you first begin using Kesimpta, you’ll use the medication almost every week, then switch to once per month. For details, see the “Kesimpta dosage” section above.

You should try to take your dose of Kesimpta on the same day of the week throughout your treatment. This helps make sure that you have a consistent amount of medication working in your body at all times. That way, the drug can be more effective at treating your condition.

To help make sure that you don’t miss a dose, try using a medication reminder. This can include setting an alarm or timer on your phone or downloading a reminder app. A kitchen timer can work, too.

When you get Kesimpta from the pharmacy, the pharmacist will add an expiration date to the label on the box. This date is typically 1 year from the date they dispensed the medication.

The expiration date helps guarantee that the medication is effective during this time. The current stance of the Food and Drug Administration (FDA) is to avoid using expired medications. If you have unused medication that has gone past the expiration date, talk with your pharmacist about whether you might still be able to use it.

Storage

How long a medication remains good to use can depend on many factors, including how and where you store the medication.

You should store Kesimpta Sensoready pens and syringes in the refrigerator at 36°F to 46°F (2°C to 8°C). To protect the medication from light, keep the pens and syringes in their original boxes until you’re ready to use them.

It’s important to not shake or freeze Kesimpta.

Disposal

Right after you’ve used a syringe, needle, or autoinjector, dispose of it in an FDA-approved sharps disposal container. This helps prevent others, including children and pets, from using the drug by accident or harming themselves with the needle. You can buy a sharps container online, or ask your doctor, pharmacist, or health insurance company where to get one.

This article provides several useful tips on medication disposal. You can also ask your pharmacist for information about how to dispose of your medication.

There are no known interactions between Kesimpta and alcohol. However, alcohol may make some multiple sclerosis (MS) symptoms worse. Both alcohol use and MS may cause difficulty walking or changes in vision. So if you have these MS symptoms, drinking alcohol may make them more severe.

Before you use Kesimpta, talk with your doctor about what amount of alcohol is safe for you to drink.

Kesimpta can interact with several other medications. It’s not known to interact with herbs, supplements, or foods.

Different interactions can cause different effects. For instance, some interactions can interfere with how well a drug works. Other interactions can increase the number of side effects or make them more severe.

Kesimpta and other medications

Below are medications that can interact with Kesimpta. This list doesn’t contain all drugs that may interact with Kesimpta.

Before using Kesimpta, talk with your doctor and pharmacist. Tell them about all prescription, over-the-counter, and other drugs you take. Also tell them about any vitamins, herbs, and supplements you use. Sharing this information can help you avoid potential interactions.

If you have questions about drug interactions that may affect you, ask your doctor or pharmacist.

Types of drugs that can interact with Kesimpta include medications that weaken your immune system. Kesimpta itself may weaken your immune system. So using Kesimpta with these medications may cause your immune system to become even weaker. This could increase the risk of infection.

Examples of these drugs include:

If you need to take any drugs that decrease your immune system during your treatment with Kesimpta, talk with your doctor or pharmacist. They may recommend monitoring you more often than usual for infection.

Kesimpta and herbs and supplements

There aren’t any herbs or supplements that have been specifically reported to interact with Kesimpta. However, you should still check with your doctor or pharmacist before using any of these products while taking Kesimpta.

Kesimpta and foods

There aren’t any foods that have been specifically reported to interact with Kesimpta. If you have any questions about eating certain foods with Kesimpta, talk with your doctor.

Kesimpta and vaccines

Before you begin treatment with Kesimpta, your doctor will typically discuss vaccines with you. They’ll likely recommend that you get any immunizations you need prior to starting treatment with the medication. This should help avoid interactions between Kesimpta and vaccines.

Live vaccines

You shouldn’t get any live (active) vaccines while you’re using Kesimpta. You also shouldn’t get them for certain lengths of time before and after you use the medication.

Live vaccines contain live but weakened pieces of the virus or bacterium they’re meant to defend against. When your immune system is healthy, live vaccines usually won’t cause infection.

Kesimpta may weaken your immune system. So if you get a live vaccine, your immune system may not be able to fight the virus or bacterium. This may cause you to become sick or develop symptoms of the illness the vaccine is meant to prevent.

Examples of live vaccines include:

You shouldn’t get live vaccines for 4 weeks before you start using Kesimpta and throughout your treatment with the drug. You should also avoid live vaccines after you stop Kesimpta treatment, until your doctor recommends that you can receive them. This is because it may take time for your immune system to strengthen after you stop using Kesimpta. You shouldn’t receive any live vaccines until your immune system has recovered.

Non-live vaccines

If possible, you should avoid getting non-live (inactive) vaccines for 2 weeks before you start using Kesimpta and during your treatment.

Non-live vaccines don’t contain live viruses or bacteria. So you’re not likely to become sick or develop symptoms of the illness the vaccine is meant to prevent.

But non-live vaccines do require your immune system to be working well for the vaccines to act correctly. Kesimpta may weaken your immune system. So if you get a non-live vaccine during your treatment, it may not work as well as usual.

Examples of non-live vaccines include:

If you have any questions about which vaccines you may need or the best time to get a vaccine while you are using Kesimpta, talk with your doctor or pharmacist. They will be able to help you determine the best vaccination schedule for you.

It’s not known if Kesimpta is safe to use while pregnant. Clinical studies of drugs that work similarly to Kesimpta showed that when they were used during pregnancy, some children were born with a weakened immune system. But it’s not known how long this effect may last or if it will occur when females* use Kesimpta.

Animal studies also show pregnant animals given Kesimpta had an increased risk of pregnancy loss.

If you’re pregnant or thinking about becoming pregnant, talk with your doctor. They can review the pros and cons of Kesimpta with you.

* Sex and gender exist on spectrums. Use of the term “female” in this article refers to sex assigned at birth.

It’s not known if Kesimpta is safe to use during pregnancy. If you’re sexually active and you or your partner can become pregnant, talk with your doctor about your birth control needs while you’re using Kesimpta.

For more information about using Kesimpta during pregnancy, see the “Kesimpta and pregnancy” section above.

For females using Kesimpta

If you’re a female* who can become pregnant, you should use an effective form of birth control when taking Kesimpta. You should continue using birth control throughout your treatment with Kesimpta and for at least 6 months after your last dose.

If you have any questions about the best birth control for you while you’re using Kesimpta, talk with your doctor.

* Sex and gender exist on spectrums. Use of the term “female” in this article refers to sex assigned at birth.

For males using Kesimpta

The manufacturer of Kesimpta doesn’t have specific recommendations about birth control use in males* using the drug. If you’re a male using Kesimpta, talk with your doctor about your birth control needs.

* Sex and gender exist on spectrums. Use of the term “male” in this article refers to sex assigned at birth.

It’s not known if Kesimpta is safe to use while breastfeeding. It’s also not known if Kesimpta passes into breast milk.

If you’re breastfeeding or thinking about it, talk with your doctor before using Kesimpta. They may recommend a different treatment option for you.

Before using Kesimpta, talk with your doctor about your health history. Kesimpta may not be right for you if you have certain medical conditions or other factors affecting your health. These include the ones mentioned below.

For more information about the potential negative effects of Kesimpta, see the “Kesimpta side effects” section above.

Hepatitis B. If you have active hepatitis B, you shouldn’t use Kesimpta. “Active” means you currently have the hepatitis B virus in your body. Your doctor will order lab tests to confirm this before you start using Kesimpta. If you do have hepatitis B, they’ll treat it before you begin using the drug.

Be sure to tell your doctor if you have a history of hepatitis B. The virus that causes hepatitis B could be in your system and become active again. Your doctor can help determine if Kesimpta is right for you.

Active infections. If you have an infection, including progressive multifocal leukoencephalopathy (PML), your doctor will treat the infection before starting Kesimpta. This is because Kesimpta may weaken your immune system, which can make it harder for your body to fight an infection. Be sure to tell your doctor about any infections that you have before you start using Kesimpta.

Recent vaccination. Before you start using Kesimpta, tell your doctor about any recent vaccinations that you’ve had. They may want you to wait a few weeks after you receive a vaccine before you begin Kesimpta treatment. For more information about how vaccines and Kesimpta interact, see “Kesimpta and vaccines” in the “Kesimpta interactions” section above.

Allergic reaction. If you’ve had an allergic reaction to Kesimpta or any of its ingredients, you shouldn’t use Kesimpta. Ask your doctor what other medications are better options for you.

Pregnancy. It’s not known if Kesimpta is safe to use during pregnancy. If you’re pregnant or planning to become pregnant, talk with your doctor. For more information, see the “Kesimpta and pregnancy” section above.

Breastfeeding. It’s not known if Kesimpta is safe to use while breastfeeding. If you’re breastfeeding or thinking about it, talk with your doctor before using Kesimpta. For more information, see the “Kesimpta and breastfeeding” section above.

Do not use more Kesimpta than your doctor recommends. For some drugs, doing so may lead to unwanted side effects or overdose.

What to do in case you use too much Kesimpta

If you think you’ve used too much of this drug, call your doctor. You can also call the American Association of Poison Control Centers at 800-222-1222 or use their online tool. But if your symptoms are severe, call 911 or your local emergency number, or go to the nearest emergency room right away.

Disclaimer: Medical News Today 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.