Kesimpta (ofatumumab)
An approved treatment for Multiple Sclerosis.
The same compound appears under different names depending on the context. Here is how to identify Ofatumumab wherever you encounter it, plus the key facts at a glance.
- Generic name
- Ofatumumab
- Brand name
- Kesimpta
- Drug class
- Monoclonal antibody (anti-CD20)
- Manufacturer
- Novartis
- How it's taken
- Comes as a prefilled pen delivering 20 mg under the skin.
A self-injectable anti-CD20 therapy given monthly under the skin at home. Offers the B-cell depletion benefits of infusion drugs like ocrelizumab in a convenient subcutaneous injection.
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Where Ofatumumab fits
Self-administered subcutaneous anti-CD20 therapy for adults with relapsing forms of MS (clinically isolated syndrome, relapsing-remitting MS, and active secondary progressive MS). It is not approved for children. Positioned as a high-efficacy option with the convenience of at-home monthly injections versus IV infusion center visits.
How Ofatumumab works
Ofatumumab targets and destroys B cells, which produce the antibodies that attack nerve cells in MS. Unlike similar drugs that require clinic infusions, ofatumumab is the first anti-B cell therapy you can inject yourself at home.
Mechanism: Anti-CD20 monoclonal antibody that depletes B cells via antibody-dependent cytotoxicity, complement-dependent cytotoxicity, and apoptosis
Side effects and safety
The most common side effects are upper respiratory infections, headache, and mild injection-site reactions. Serious infections can occur more easily. Hepatitis B can become active again, so you will be tested before starting. PML, a rare brain infection, has happened with ofatumumab at much higher IV doses used for leukemia. Other warnings include lower antibody (immunoglobulin) levels, liver injury (liver blood tests are done before starting), and injection reactions or allergic reactions that can be serious. It may harm an unborn baby, so women who can become pregnant should use effective birth control during treatment and for 6 months after stopping. Watch for signs of infection and report them.
This is not a complete list of side effects. Talk to your doctor or pharmacist about what to expect and when to seek medical attention.
Taking Ofatumumab
Comes as a prefilled pen delivering 20 mg under the skin. Start with injections at weeks 0, 1, and 2, then one injection every month. You inject into your abdomen or thigh at home, or a caregiver can inject into the outer upper arm. A prefilled syringe is also available.
Availability and cost
Only available as the brand-name product.
Anti-CD20 monoclonal antibody administered as a monthly subcutaneous self-injection, offering convenience over IV anti-CD20 therapies. Specialty biologic pricing.
Help paying for Kesimpta
Pick your insurance to see which help fits. Drugmaker copay cards can't be used with Medicare, Medicaid or TRICARE; charity funds are the usual route there.
- Copay help
Co-Pay Plus: eligible patients with private insurance may pay as little as $0; combined annual limit up to $18,000.
For: private insurance · source - Bridge or quick-start supply
If a commercially insured patient's coverage is denied pending prior authorization, up to 15 doses may be provided free until coverage is approved.
For: private insurance · source - Insurance and case manager help
Dedicated Novartis Patient Support team helps with insurance paperwork, coverage questions, plan changes and ongoing support. Call 855-KESIMPTA, option 2 for financial and insurance help.
The official page does not say who qualifies. Ask the program. · source - Free medicine program
Novartis Patient Assistance Foundation may provide the medicine at no cost to patients who are uninsured or have government insurance and meet income guidelines.
For: no insurance, Medicare, Medicaid, TRICARE · source
Good to know: Free drug is through the Novartis Patient Assistance Foundation (NPAF), a separate nonprofit; call 1-800-277-2254. Co-Pay Plus and bridge are not valid with Medicare, Medicaid, TRICARE, VA or other government coverage.
- From a charity · TotalAssist (formerly PAN Foundation)Multiple Sclerosis fundOpen
Pays for: Out-of-pocket costs for approved medications, up to $8,000 per year. Requires Medicare, Medicaid or TRICARE.
- From a charity · The Assistance FundMultiple Sclerosis fundWaitlist
Pays for: Copays, coinsurance, deductibles and other health-related expenses.
The foundation says: “WAITLIST — Accepting Waitlist Patients. TAF is currently accepting requests to join the enrollment waitlist for this program. Waitlists a…”
Clinical trial results
In two Phase 3 trials, ofatumumab was more effective than oral teriflunomide at reducing relapses and preventing new brain lesions. Patients preferred it because it could be self-administered at home.
Development history
Ofatumumab was first approved in 2009 as an IV cancer medicine for chronic lymphocytic leukemia (Arzerra). Novartis developed the low-dose monthly injection for MS, which the FDA approved as Kesimpta on August 20, 2020. It was the first self-administered B-cell therapy for MS. The innovation of home injections instead of clinic infusions made treatment more convenient.
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Common questions about Ofatumumab
▸What is Ofatumumab (Kesimpta)?
A self-injectable anti-CD20 therapy given monthly under the skin at home. Offers the B-cell depletion benefits of infusion drugs like ocrelizumab in a convenient subcutaneous injection.
▸How does Ofatumumab work?
Ofatumumab targets and destroys B cells, which produce the antibodies that attack nerve cells in MS. Unlike similar drugs that require clinic infusions, ofatumumab is the first anti-B cell therapy you can inject yourself at home.
▸What are the side effects of Ofatumumab?
The most common side effects are upper respiratory infections, headache, and mild injection-site reactions. Serious infections can occur more easily. Hepatitis B can become active again, so you will be tested before starting. PML, a rare brain infection, has happened with ofatumumab at much higher IV doses used for leukemia. Other warnings include lower antibody (immunoglobulin) levels, liver injury (liver blood tests are done before starting), and injection reactions or allergic reactions that can be serious. It may harm an unborn baby, so women who can become pregnant should use effective birth control during treatment and for 6 months after stopping. Watch for signs of infection and report them.
▸How is Ofatumumab taken?
Comes as a prefilled pen delivering 20 mg under the skin. Start with injections at weeks 0, 1, and 2, then one injection every month. You inject into your abdomen or thigh at home, or a caregiver can inject into the outer upper arm. A prefilled syringe is also available.
▸Is Ofatumumab FDA approved?
Yes, Ofatumumab (Kesimpta) is FDA approved (2020) for the treatment of Multiple Sclerosis.
▸What is Kesimpta and what is it used for?
Kesimpta is the brand name of ofatumumab, a prescription injection from Novartis for adults with relapsing forms of multiple sclerosis.
Approved uses: The FDA label covers clinically isolated syndrome, relapsing-remitting MS and active secondary progressive MS.
Not approved for: Children or primary progressive MS.
Related product: The same antibody was approved earlier, at much higher intravenous doses, as Arzerra for chronic lymphocytic leukemia.
Source: FDA label for Kesimpta, DailyMed, effective 2026-04-01
▸What is the generic name for Kesimpta, and is there a generic version?
The generic name is ofatumumab, and there is no generic or biosimilar version of Kesimpta in the United States.
Same medicine: The 2 names refer to the same medicine.
Only product: Kesimpta is the only ofatumumab product sold for MS.
▸What drug class is Kesimpta, and how does it work?
Kesimpta is a CD20-directed cytolytic antibody, usually called an anti-CD20 B-cell therapy, in the same class as Ocrevus and Briumvi.
How it works: It attaches to CD20, a protein on the surface of B cells, and removes those cells from the blood through the body's own immune mechanisms.
Why that matters: B cells are believed to drive the inflammation that damages nerve coverings in MS, so fewer B cells means fewer relapses and fewer new lesions.
Label note: The label notes the exact way it helps in MS is presumed rather than proven.
Source: FDA label for Kesimpta, DailyMed, effective 2026-04-01
▸What are the side effects of Kesimpta?
The most common side effects in the 2 Phase 3 trials were upper respiratory infections, injection-related reactions, headache and injection-site reactions.
Most common: Reported in more than 10% of people were upper respiratory infections (39%, versus 38% on teriflunomide), injection-related reactions such as fever, headache, muscle aches, chills and fatigue (21% versus 15%), headache (13% versus 12%), and local injection-site reactions such as redness, pain, itching and swelling (11% versus 6%).
Also more common: Urinary tract infections (10% versus 8%), back pain (8% versus 6%) and low immunoglobulin M on blood tests (6% versus 2%).
Serious risks: Infections including hepatitis B reactivation, injection and allergic reactions, reduced immunoglobulins, liver injury, and harm to a fetus.
Source: FDA label for Kesimpta, DailyMed, effective 2026-04-01
▸What are the Kesimpta injection side effects, and do they get better?
Injection reactions are most common with the first dose and fall off sharply after that.
Whole-body reactions: Fever, chills, headache and muscle aches in the hours after an injection happened in 14.4% of people with the first injection, 4.4% with the second and under 3% from the third on, and 99.8% were mild or moderate.
Injection-site reactions: Local reactions at the injection site were all mild or moderate.
Allergic reactions: Since approval, rarer allergic reactions including anaphylaxis, angioedema, hives and rash have been reported.
What to do: A severe reaction means stopping the drug and getting care.
Source: FDA label for Kesimpta, DailyMed, effective 2026-04-01
▸Where do you inject Kesimpta?
Kesimpta is injected under the skin of the abdomen or the front of the thigh, and a caregiver can also inject into the outer upper arm.
Abdomen: Stay away from the 2-inch area around the navel.
Site rotation: Rotate sites and avoid skin that is tender, bruised, red, scaly or hard.
Device: Kesimpta comes as a 20 mg single-dose Sensoready pen or a prefilled syringe; the pen is used for self-injection and does not need to be mixed.
Source: FDA label for Kesimpta, DailyMed, effective 2026-04-01
▸Is Kesimpta an infusion or an injection?
Kesimpta is an injection, not an infusion.
How it is given: Kesimpta is given only under the skin, from a pen or syringe, and most people inject themselves at home after training. It is never infused into a vein.
Why the confusion: It comes from Arzerra, the older intravenous form of ofatumumab used for leukemia, and from Ocrevus, a related MS drug that is given as an infusion.
Source: FDA label for Kesimpta, DailyMed, effective 2026-04-01
▸What is the Kesimpta dosing schedule?
The dose is 20 mg every time.
Starting doses: The first 3 doses are given 1 week apart, at week 0, week 1 and week 2.
Maintenance: Then 1 injection a month starting at week 4.
Before the first dose: The label requires a hepatitis B test, immunoglobulin levels and liver blood tests.
Source: FDA label for Kesimpta, DailyMed, effective 2026-04-01
▸Does Kesimpta cause urinary tract infections?
Urinary tract infections were reported in 10% of people on Kesimpta in the trials compared with 8% on teriflunomide, so the drug adds a small amount of risk.
Overall infections: Overall infection rates were similar between the 2 groups (51.6% versus 52.7%), and serious infections were 2.5% versus 1.8%.
What to do: Any infection should be treated promptly, and the label says to delay an injection while an active infection is being treated.
Source: FDA label for Kesimpta, DailyMed, effective 2026-04-01
▸Does Kesimpta increase the risk of cancer?
The Kesimpta label does not carry a warning about cancer, and no increase in cancers was reported in its MS trials.
Compared with Ocrevus: This differs from the Ocrevus label, which includes a note about malignancies.
Screening: Anti-CD20 drugs as a class suppress part of the immune system, so standard cancer screening should continue on schedule.
Source: FDA label for Kesimpta, DailyMed, effective 2026-04-01
▸Does Kesimpta weaken your immune system?
Partly; it removes B cells, one arm of the immune system.
Why it matters: That is why infections are the main risk and why immunoglobulin levels are checked before, during and after treatment.
Immunoglobulin changes: Immunoglobulin M fell in 7.7% of patients versus 3.1% on teriflunomide, and 3.4% stopped the drug for that reason. Immunoglobulin G did not fall by the end of the study.
Vaccines: Live vaccines are not recommended during treatment or afterward until B cells return. The label advises completing live vaccines at least 4 weeks and other vaccines at least 2 weeks before starting.
Source: FDA label for Kesimpta, DailyMed, effective 2026-04-01
▸Who should not take Kesimpta?
People with an active hepatitis B infection, and anyone who has had a serious allergic reaction or a life-threatening injection reaction to ofatumumab, should not take Kesimpta.
Past hepatitis B: People who have had hepatitis B in the past need a liver specialist involved before starting.
Other MS drugs: It has not been studied in combination with other MS drugs.
Immune-suppressing medicines: Combining it with other immune-suppressing medicines raises infection risk.
Source: FDA label for Kesimpta, DailyMed, effective 2026-04-01
▸Can Kesimpta affect the liver?
Yes, rarely.
What has been reported: Since approval, cases of significant liver injury without viral hepatitis have been reported with anti-CD20 MS drugs including Kesimpta, appearing weeks to months after a dose.
Testing: The label now requires liver blood tests before starting.
Symptoms to report: Check liver tests promptly if you develop new or worsening fatigue, loss of appetite, nausea, vomiting, pain in the upper right abdomen, dark urine or yellowing of the skin or eyes.
Source: FDA label for Kesimpta, DailyMed, effective 2026-04-01
▸How should Kesimpta be stored, and what is its shelf life?
Keep Kesimpta pens and syringes in the refrigerator, and never freeze or shake them.
Refrigerator: Store at 36 to 46 degrees F, in the original carton to protect from light.
Room temperature: If needed, Kesimpta can sit at room temperature up to 86 degrees F for a total of 7 days. Write the date it came out on the carton, and discard it after 7 days out.
Shelf life: The expiration date is printed on the carton and pen.
Source: FDA label for Kesimpta, DailyMed, effective 2026-04-01
▸Is it safe to take Kesimpta while pregnant or trying to conceive?
The label says Kesimpta may harm a fetus, based on animal studies showing B-cell depletion in offspring.
Contraception: The label advises effective contraception during treatment and for at least 6 months after the last dose.
Newborns: Babies born to mothers treated during pregnancy should not receive live vaccines until their B-cell counts are confirmed normal.
Pregnancy registry: A pregnancy registry run by MotherToBaby tracks outcomes.
What to do: Decisions about continuing treatment around pregnancy belong with your neurologist.
Source: FDA label for Kesimpta, DailyMed, effective 2026-04-01
▸What did the Kesimpta clinical trials show?
In 2 trials, Kesimpta cut the annualized relapse rate by 51% and 58% compared with oral teriflunomide.
Trial design: The ASCLEPIOS I and II trials (NCT02792218 and NCT02792231) randomized 1,882 adults with relapsing MS to Kesimpta or oral teriflunomide for up to 120 weeks.
Results: Kesimpta cut the annualized relapse rate by 51% in the first trial and 58% in the second, with fewer new brain lesions and a lower rate of confirmed disability worsening in the pooled analysis.
Approval: The FDA approved it on August 20, 2020 on the strength of those 2 trials.
Source: FDA label for Kesimpta, DailyMed, effective 2026-04-01
▸How much does Kesimpta cost?
Kesimpta is a specialty biologic with no generic, so the list price runs to tens of thousands of dollars a year and what you pay depends on your insurance.
Assistance: Novartis Patient Support offers a copay program for people with commercial insurance and can supply the drug at no cost while a coverage decision is pending.
If denied: If your plan denies it, our guide to appealing a rare disease drug denial walks through the process.
▸How does ofatumumab compare to ocrelizumab?
Both target CD20 on B cells and are highly effective at reducing relapses.
Main difference: Convenience, since ofatumumab is a monthly self-injection at home, while ocrelizumab (Ocrevus) is given by a healthcare professional every 6 months, as an infusion or an under-the-skin injection.
Head-to-head data: There is no head-to-head trial.
Choosing: The choice often comes down to lifestyle, access to an infusion center and insurance.