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Kesimpta Side Effects

Generic name: ofatumumab

Medically reviewed by Philip Thornton, DipPharm. Last updated on Mar 7, 2023.

Note: This document contains side effect information about ofatumumab. Some dosage forms listed on this page may not apply to the brand name Kesimpta.

Applies to ofatumumab: solution.


Intravenous route (Solution)

Hepatitis B Virus (HBV) reactivation can occur in patients receiving CD20-directed cytolytic antibodies, including ofatumumab, in some cases resulting in fulminant hepatitis, hepatic failure, and death. Progressive Multifocal Leukoencephalopathy (PML) resulting in death can occur in patients receiving CD20-directed cytolytic antibodies, including ofatumumab.

Serious side effects of Kesimpta

Along with its needed effects, ofatumumab (the active ingredient contained in Kesimpta) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor or nurse immediately if any of the following side effects occur while taking ofatumumab:

More common

  • Black, tarry stools
  • bloating or swelling of the face, arms, hands, lower legs, or feet
  • blurred vision
  • body aches or pain
  • chest pain or tightness
  • chills
  • confusion
  • cough producing mucus
  • difficult or labored breathing
  • dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
  • ear congestion
  • facial swelling
  • fainting
  • fast heartbeat
  • feeling of warmth
  • headache
  • hives or welts, itching, or skin rash
  • increased sweating
  • lightheadedness
  • loss of voice
  • lower back or side pain
  • nausea or vomiting
  • painful blisters on the trunk of the body
  • painful or difficult urination
  • pale skin
  • rapid, shallow breathing
  • redness of the face, neck, arms, and occasionally, upper chest
  • runny or stuffy nose
  • sneezing
  • sore throat
  • tingling of the hands or feet
  • trouble breathing
  • ulcers, sores, or white spots in the mouth
  • unusual bleeding or bruising
  • unusual tiredness or weakness
  • unusual weight gain or loss

Less common

Incidence not known

  • Blistering, peeling, or loosening of the skin
  • dark urine
  • diarrhea
  • fluid-filled skin blisters
  • joint or muscle pain
  • light-colored stools
  • no blood pressure or pulse
  • red skin lesions, often with a purple center
  • red, irritated eyes
  • sensitivity to the sun
  • skin thinness
  • stopping of heart
  • unconsciousness
  • yellow eyes or skin

Check with your doctor immediately if any of the following side effects occur while taking ofatumumab:

More common

  • Bladder pain
  • bloody or cloudy urine
  • body aches or pain
  • chills
  • cough
  • difficult, burning, or painful urination
  • dryness or soreness of throat
  • ear congestion
  • fever
  • flushing, redness of skin
  • frequent urge to urinate
  • hoarseness
  • joint pain
  • loss of voice
  • lower back or side pain
  • muscle aches
  • pain or tenderness around eyes and cheekbones
  • pain, itching, swelling of the skin
  • runny nose
  • sneezing
  • sore throat
  • stuffy or runny nose
  • sweating
  • swollen joints
  • tender, swollen glands in the neck
  • trouble in swallowing
  • unusually warm skin
  • voice changes
  • vomiting

Other side effects of Kesimpta

Some side effects of ofatumumab may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

  • Back pain
  • muscle aches
  • redness of the skin
  • trouble sleeping

Less common

  • Bleeding, blistering, burning, coldness, discoloration of the skin, feeling of pressure, hives, infection, inflammation, itching, lumps, numbness, pain, rash, redness, scarring, soreness, stinging, swelling, tenderness, tingling, ulceration, or warmth at the injection site
  • muscle spasms
  • pain or tenderness around the eyes and cheekbones

For Healthcare Professionals

Applies to ofatumumab: intravenous solution, subcutaneous solution.


Very common (10% or more): Neutropenia (up to 27%), anemia (up to 18%)

Common (1% to 10%): Leukopenia, febrile neutropenia, thrombocytopenia

Uncommon (0.1% to 1%): Agranulocytosis, coagulopathy, red cell aplasia, lymphopenia[Ref]


Very common (10% or more): Upper respiratory tract infection (up to 19%), pneumonia (up to 23%), cough (up to 19%), dyspnea (up to 14%), bronchitis (up to 11%), lower respiratory tract infection

Common (1% to 10%): Sinusitis, nasopharyngitis, bronchospasm, hypoxia, dyspnea, chest discomfort, pharyngolaryngeal pain, nasal congestion

Uncommon (0.1% to 1%): Pulmonary edema[Ref]


Very common (10% or more): Diarrhea (up to 18%), nausea (up to 11%)

Common (1% to 10%): Upper abdominal pain

Uncommon (0.1% to 1%): Small bowel obstruction[Ref]


Very common (10% or more): Rash (e.g., rash, rash macular, rash vesicular) (up to 14%)

Common (1% to 10%): Urticaria, hyperhidrosis, erythema, pruritus

Uncommon (0.1% to 1%): Coagulopathy, red cell aplasia

Postmarketing reports: Stevens-Johnson syndrome, porphyria cutanea tarda[Ref]


Common (1% to 10%): Arthralgia, back pain, chills, muscle spasms, rigors[Ref]


Common (1% to 10%): Insomnia[Ref]

Nervous system

Common (1% to 10%): Headache[Ref]


Common (1% to 10%): Hypertension, hypotension, tachycardia

Uncommon (0.1% to 1%): Bradycardia

Postmarketing reports: Cardiac arrest (infusion related)[Ref]


Common (1% to 10%): Urinary tract infection[Ref]


Rare (less than 0.1%): Hepatitis B infection and reactivation[Ref]


Common (1% to 10%): Anaphylactoid reactions, hypersensitivity

Uncommon (0.1% to 1%): Anaphylactic shock, cytokine release syndrome[Ref]


Common (1% to 10%): Herpes simplex (e.g., oral herpes, herpes, herpes virus infection, genital herpes), influenza, herpes zoster, hypogammaglobulinemia, bacterial infections, viral infections, fungal infections, sepsis (e.g., sepsis, neutropenic sepsis, bacteremia, septic shock)

Uncommon (0.1% to 1%): Immunogenicity[Ref]


Very common (10% or more):

Common (1% to 10%): Peripheral edema

Uncommon (0.1% to 1%): Tumor lysis syndrome[Ref]


Very common (10% or more): Pyrexia (up to 20%), fatigue (up to 15%)[Ref]

Frequently asked questions


1. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

2. Pharmaceutical Society of Australia "APPGuide online. Australian prescription products guide online." (2006):

3. "Product Information. Arzerra (ofatumumab)." GlaxoSmithKline (2009):

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.