Ofatumumab Injection (Multiple Sclerosis)
Kesimpta (ofatumumab) is a self-injected antibody treatment for relapsing forms of multiple sclerosis in adults.
🧬 Where this information comes from Click to expand
The clinical label records used on this page are FDA-filed Structured Product Labeling (SPL) retrieved through openFDA. We identified 1 clinical label set within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. Forms, routes, brands, labelers, strengths, and NDC product-record counts are built separately from matching FDA National Drug Code Directory records. The linked DailyMed document is a representative official source for verification, not the page’s only clinical source. View the linked label on DailyMed →
📖 Ofatumumab Injection (Multiple Sclerosis): Patient Information Guide
A plain-language walkthrough of Ofatumumab Injection (Multiple Sclerosis) — what it treats, how it works, how it’s taken, side effects, warnings and interactions. Tap any section to expand it.
🎯What it's used for▾
Kesimpta treats relapsing forms of multiple sclerosis (MS) in adults. The specific forms it covers include:
- Clinically isolated syndrome — a first neurological episode that may signal MS
- Relapsing-remitting MS — the most common type, with defined flares and periods of recovery
- Active secondary progressive MS — a stage where the disease gradually worsens but still has active inflammatory activity
⚙️How it works▾
Kesimpta is a monoclonal antibody — a lab-made protein designed to seek out a specific target. It locks onto a protein called CD20 on the surface of B lymphocytes (a type of white blood cell). Once it binds, it triggers two immune processes that destroy those B cells. Since overactive B cells are thought to contribute to the nerve inflammation and damage seen in MS, reducing them helps calm the disease.
The exact reason depleting B cells helps MS is not fully understood, but clinical studies show it significantly reduces relapses and disease activity while on treatment.
💊How it's taken▾
Kesimpta is given as a subcutaneous (under-the-skin) injection using a pre-filled autoinjector pen — similar to an EpiPen. There are no dietary restrictions. A short loading phase with injections on three consecutive weeks gets levels up quickly, followed by one injection per month for ongoing treatment.
- Loading phase: injections at Week 0, Week 1, and Week 2
- Maintenance: one injection per month starting at Week 4
- If you miss a dose, take it as soon as you remember — don't wait for your next scheduled date
- After a missed dose, resume your regular monthly schedule
🤒Side effects — in detail▾
The most common side effects reported with Kesimpta include:
- Upper respiratory infections (colds, sinus infections, sore throats)
- Headache
- Systemic injection reactions — chills, fatigue, or flu-like feelings shortly after injecting
- Local injection site reactions — redness or soreness at the shot site
- Urinary tract infections
- Declining IgM levels (a type of protective antibody that can drop over time)
More serious reactions — including severe infections, liver injury, severe allergic reactions (anaphylaxis), or very low immunoglobulin levels — require immediate medical attention. Don't ignore a fever, trouble breathing, or yellowing of the skin.
⚠️Warnings & precautions▾
- Serious infections: Because Kesimpta depletes B cells, your immune defenses are lowered. Serious, even life-threatening infections — bacterial, fungal, or viral — can occur. Delay your injection if you have an active infection and call your doctor.
- Hepatitis B reactivation: You must be screened for hepatitis B before starting. If you have active hepatitis B, Kesimpta cannot be used. Carriers need specialist input.
- Low immunoglobulins: Over time, levels of protective antibodies (immunoglobulins) can fall. Your doctor will monitor these; very low levels may mean treatment needs to stop.
- Liver injury: Clinically significant liver damage has been reported. Liver function tests are needed before and during treatment.
- Fetal harm: Based on animal studies, Kesimpta may harm an unborn baby. Use reliable contraception during treatment and for 6 months after your last dose.
- Vaccines: Live vaccines cannot be given during treatment or until your B cells recover. Get all needed vaccines before starting.
🔀What it interacts with▾
Kesimpta doesn't go through the usual liver enzyme pathways most drugs use, but it does interact with therapies that affect the immune system:
- Immunosuppressant drugs (e.g., systemic corticosteroids): Combining these with Kesimpta multiplies the immune-suppressing effect, raising infection risk significantly
- Other MS disease-modifying therapies: Switching from one MS drug to another requires careful planning — some leave lasting immune effects that can stack on top of Kesimpta's action
- Live vaccines: Cannot be given during Kesimpta treatment or until B cells have recovered after stopping — the weakened immune response could let the vaccine virus cause illness
This is not a complete list of interactions. Always talk with your doctor or pharmacist before starting, stopping, or changing any medication.
📋Before taking it▾
- You must not use Kesimpta if you have an active hepatitis B infection or have had a life-threatening allergic reaction to ofatumumab
- Hepatitis B screening and liver function tests are required before your first dose
- Your immunoglobulin (protective antibody) levels should be checked before starting
- Get all recommended vaccines up to date before starting — live vaccines at least 4 weeks prior, inactivated vaccines at least 2 weeks prior
- Pregnancy: The drug may cross the placenta and affect the baby's immune system — effective contraception is required during treatment and for 6 months after stopping; enroll in the MotherToBaby pregnancy registry if you become pregnant
- Avoid giving live vaccines to infants born to mothers who used Kesimpta during pregnancy, until the baby's B-cell count is confirmed normal
- Tell your doctor about all immunosuppressant or immune-modulating medications you take
- Delay your dose if you have any active infection — wait until it clears
📡Pharmacodynamics — effects in the body▾
Kesimpta works by depleting B cells — a type of immune cell tracked using a marker called CD19+. Within just one to two weeks of starting treatment, the vast majority of patients see B-cell counts fall below the normal lower limit. By 12 weeks, nearly all patients on Kesimpta have significantly depleted B-cell levels, and this depletion is maintained throughout treatment.
When treatment stops, B cells gradually return. On average, it takes roughly 24 weeks (about 6 months) after the last dose for B-cell counts to recover to normal or baseline levels.
🔬Pharmacokinetics — how your body processes it▾
After a subcutaneous injection, Kesimpta is primarily absorbed through the lymphatic system — the network of vessels that is part of the immune system — rather than directly into the bloodstream. It stays distributed in a relatively small volume within the body, suggesting it stays mostly in the blood and lymph tissue rather than spreading broadly into other tissues.
Ofatumumab is cleared from the body in two ways: a steady breakdown pathway (like most proteins), and a faster B-cell-mediated pathway that shrinks as B cells are depleted. This means the drug's half-life (the time for levels to fall by half) actually lengthens as treatment continues — settling at roughly 16 days once B cells are depleted. The drug is broken down into small peptides and amino acids; it is not cleared by the kidneys or processed by the liver's usual drug-metabolizing enzymes.
📦How to store it▾
refrigerated at 2ºC to 8ºC (36ºF to 46ºF). protect from light until the time of use. Do not freeze.
📄 Written from Ofatumumab Injection (Multiple Sclerosis)’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Every point is grounded in that labeling — nothing is invented. How we use AI →
Supplements & herbs that interact with Ofatumumab Injection (Multiple Sclerosis)
53 supplements and herbal products have documented interactions with Ofatumumab Injection (Multiple Sclerosis) in the licensed clinical database we use. Most are manageable — but your pharmacist should know about everything you take, including vitamins and herbals.
- Moderate · 52
- Minor · 1
Educational information from a licensed clinical database (Natural Medicines) — see our data sources & update cadence. Not medical advice: an interaction being documented does not mean it will happen to you; do not start or stop medications or supplements without professional guidance.
🩺 Pharmacist Counseling Corner
Quick, plain-English answers to the questions patients ask most about Ofatumumab Injection (Multiple Sclerosis) — the kind of thing our pharmacy team would talk through with you at the counter.
What exactly is Kesimpta doing to treat my MS? ▾
How do I actually take this — do I have to go to a clinic for every injection? ▾
What side effects should I expect, and which ones mean I need to call someone? ▾
I've heard it can cause infections — how worried should I be? ▾
Can I get vaccinated while I'm on Kesimpta? ▾
Is it safe to use Kesimpta if I'm pregnant or trying to get pregnant? ▾
Is Ofatumumab Injection (Multiple Sclerosis) available over the counter? ▾
💬 Answers drafted from Ofatumumab Injection (Multiple Sclerosis)’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Grounded in that labeling — nothing is made up. How we use AI →
🧰 Keep exploring
📈 How widely Ofatumumab Injection (Multiple Sclerosis) is used
A general measure of how commonly Ofatumumab Injection (Multiple Sclerosis) is prescribed, based on Medicaid — one of the largest public drug programs. The figure below is prescriptions filled in Q1–Q4 2025, summed across every form and brand of the drug.
Think of this as a proxy for how widely Ofatumumab Injection (Multiple Sclerosis) is used, drawn from freely available public data. Medicaid is just one program — these numbers don’t include Medicare, other government coverage, or commercial and cash-pay prescriptions, so real-world use is higher than what’s shown here.
How commonly is Ofatumumab Injection (Multiple Sclerosis) prescribed? Of the 1,596 medications we measure, Ofatumumab Injection (Multiple Sclerosis) ranks #660 by Medicaid prescriptions — more than 59% of them.
Utilization by Ofatumumab Injection (Multiple Sclerosis) product
Pick a product to see its own Medicaid numbers. Each chip is one clinical product — a specific strength & dosage form as defined by RxNorm — with brand-name and generic versions combined.
0.4 ML ofatumumab 50 MG/ML Pen Injector
Summed across the 1 of 2 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 2390949
Shares are of the Medicaid prescriptions shown here. Product grouping follows RxNorm (the National Library of Medicine’s drug terminology), so “one product” means one strength & dosage form regardless of manufacturer. Dollar figures are gross Medicaid reimbursement before mandatory rebates — rebates (often large, especially for brand-name drugs) are confidential, so actual net cost to Medicaid is lower than shown.
Source: Medicaid State Drug Utilization Data (CMS), aggregated by generic ingredient — summed across every NDC (all brands, strengths, salt forms and dosage forms) of Ofatumumab Injection (Multiple Sclerosis), and across all states and both fee-for-service and managed-care claims. A general popularity signal; it excludes Medicare, commercial insurance and cash prescriptions, so it is not total U.S. use. Based on the 1 of 2 listed Ofatumumab Injection (Multiple Sclerosis) NDCs with Medicaid activity.
📈 What people report — real-world data (FDA FAERS)
After a medicine reaches the market, patients, doctors and drugmakers can send the FDA reports of problems they think may be linked to it. Here’s what’s been reported for Ofatumumab Injection (Multiple Sclerosis) — a signal of what to watch for, not proof the drug caused it.
Source: openFDA, from the FDA Adverse Event Reporting System (FAERS). These are voluntary reports — they don’t prove the drug caused the effect, and counts reflect how often something was reported, not how often it actually happens. Reports also often name the very problem the medicine is taken for — a common reason to file one is that the drug didn’t help — so for a pain reliever you may see “pain” high on the list; that points to why the report was filed, not to the drug causing the symptom. This counts every report that lists Ofatumumab Injection (Multiple Sclerosis) in any role, so the total runs higher than the FDA’s official dashboard, which counts only cases where the drug is the suspect. For the authoritative figures, see the FDA FAERS Public Dashboard. Always talk to your pharmacist or doctor.
🏛️ The road to your pharmacy
How Ofatumumab Injection (Multiple Sclerosis) went from FDA review to the pharmacy shelf — the key milestones in its regulatory journey.
Source: Drugs@FDA.
🚨 Recall history
A recall is when a specific batch of a medicine is pulled from the market — usually a manufacturing issue, not a problem with the drug itself. Class I is most serious, Class III least.
Source: openFDA drug enforcement (recall) reports.
RxNorm Concept Web — From Ingredient to Every Form and Strength
This page starts with one ingredient concept (IN). The branches below show its dose-form concepts (SCDF), then the available clinical drug and strength concepts (SCD). Combination products remain separate concepts with their own pages.
RxCUI 712566 2 dose forms · 3 strengths
-
Dose form (SCDF) Injection RxCUI 1658041No current FDA listingClinical drug / strength (SCD) 5 ML ofatumumab 20 MG/MLRxCUI 165804750 ML ofatumumab 20 MG/MLRxCUI 1658042 -
Dose form (SCDF) Pen Injector RxCUI 2390948No current FDA listingClinical drug / strength (SCD) 0.4 ML ofatumumab 50 MG/MLRxCUI 2390949
Look up RxCUI 712566 in the RxCUI Atlas →
RxNorm is the U.S. National Library of Medicine’s normalized drug vocabulary. Its concept hierarchy can include forms that are not currently marketed; the status on each branch compares that concept with current FDA listings. RxCUIs identify vocabulary concepts, not individual packages or manufacturers.
📦 Supply & shortage status
Whether Ofatumumab Injection (Multiple Sclerosis) is in short supply in the U.S. right now, plus any shortage history the FDA has on record. A shortage usually reflects a manufacturing or demand issue — not a safety problem with the drug.
Source: openFDA, from the FDA Drug Shortages database.
🏷️ Sold under these brand names
RxNorm drug class
Ofatumumab Injection (Multiple Sclerosis) belongs to the CD20-directed Cytolytic Antibody class.
Classified by RxNorm RxClass — the U.S. National Library of Medicine's standardized drug-classification service (Established Pharmacologic Class from the FDA, the ATC drug family from the WHO, and mechanism of action). Reference only, not medical advice.
🔬 Where this comes from
Core label, product, RxNorm, safety, and utilization data on this page come from the sources identified below. AI-written, editorial, and licensed sections are labeled separately.
How we combine label and product data
HelloPharmacist combines public FDA and NLM records; we don’t author the underlying clinical facts. We identified 1 FDA-filed SPL label set within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. The representative label is the starting point for the displayed reference monograph; the 12 largest stored in-scope SPL records, which may include that representative, are compared section by section, and the longest available version of each section is retained. Forms, routes, brands, labelers, product-listed strengths, and product-record counts are aggregated separately from ingredient-matched FDA NDC Directory records; package records listed above are associated with the linked SPL; and the normalized concept hierarchy comes from NLM RxNorm.
For canonical ingredient pages, bounded product-attributed indication and administration excerpts may be added to the AI evidence, and the generator is instructed to preserve available product, brand, route, and form qualifiers instead of treating one label as universal. Where a section is identified as AI-written, its plain-language text is generated from bounded label evidence. New draft drug pages remain in the admin review queue before first publication. Novartis Pharmaceuticals Corporation is the representative DailyMed label linked for verification and dates; it is not the sole source used for the page.
This is general education, not medical advice — always consult your doctor or pharmacist about your medications and any medical condition. For the exact wording of the linked representative label, view that label on DailyMed; some displayed composite sections may come from other in-scope SPL labels. Learn how we use AI and our data sources & update cadence.