Natalizumab Side Effects

Medically reviewed by Philip Thornton, DipPharm. Last updated on Apr 1, 2025.

Applies to natalizumab: intravenous solution.

Important warnings This medicine can cause some serious health issues

Intravenous route (solution)

Progressive Multifocal Leukoencephalopathy. Natalizumab increases the risk of progressive multifocal leukoencephalopathy (PML), an opportunistic viral infection of the brain that usually leads to death or severe disability.Risk factors for PML include the presence of anti-JC virus antibodies, duration of therapy, and prior use of immunosuppressants.

These factors should be considered in the context of expected benefit when initiating and continuing treatment with natalizumab.Monitor patients, and withhold natalizumab immediately at the first sign or symptoms suggestive of PML.Because of the risk of PML, natalizumab is available only through a restricted distribution program called the TOUCH® Prescribing Program.

Intravenous route (solution)

Progressive Multifocal Leukoencephalopathy Natalizumab products increase the risk of progressive multifocal leukoencephalopathy (PML), an opportunistic viral infection of the brain that usually leads to death or severe disability.

Risk factors for the development of PML include the presence of anti-JCV antibodies, duration of therapy, and prior use of immunosuppressants.

These factors should be considered in the context of expected benefit when initiating and continuing treatment with natalizumab-sztn.

Healthcare professionals should monitor patients on natalizumab-sztn for any new sign or symptom that may be suggestive of PML.

Natalizumab-sztn dosing should be withheld immediately at the first sign or symptom suggestive of PML.

For diagnosis, an evaluation that includes a gadolinium-enhanced magnetic resonance imaging (MRI) scan of the brain and, when indicated, cerebrospinal fluid analysis for JC viral DNA are recommended.

Because of the risk of PML, natalizumab-sztn is available only through a restricted program under a Risk Evaluation and Mitigation Strategy (REMS) called the TYRUKO REMS Program.

Serious side effects of natalizumab

Along with its needed effects, natalizumab 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 natalizumab:

More common side effects

• bladder pain
• blistering, crusting, irritation, itching, or reddening of the skin
• bloody or cloudy urine
• body produces substance that can bind to drug making it less effective or cause side effects
• chest tightness
• cough
• difficult, burning, or painful urination
• difficulty with swallowing
• dizziness
• fast heartbeat
• frequent, strong, or increased urge to urinate
• hives, itching, skin rash
• itching of the vagina or genital area
• lower back or side pain
• pain during sexual intercourse
• passing urine more often
• puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
• thick, white vaginal discharge with no odor or with a mild odor
• unusual tiredness or weakness

Rare side effects

• blurred vision
• changes in behavior
• chest pain
• confusion
• difficult or labored breathing
• fainting or lightheadedness when getting up suddenly from a lying or sitting position
• feeling of warmth
• feeling unusually cold
• fever
• gaseous abdominal or stomach pain
• nausea
• redness of the face, neck, arms, and occasionally, upper chest
• shivering
• sneezing
• sore throat
• stomach fullness
• sweating
• thoughts of killing oneself
• yellow eyes or skin

Incidence not known

• back, leg, or stomach pains
• black, tarry stools
• bleeding gums
• chills
• dark urine
• drowsiness
• general body swelling
• headache
• heavier menstrual periods
• loss of appetite
• nosebleeds
• pale skin
• pinpoint red spots on the skin
• seizures
• unusual bleeding or bruising
• vomiting

Other side effects of natalizumab

Some side effects of natalizumab 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 side effects

• cracked, dry, scaly skin
• diarrhea
• difficulty with moving
• discouragement
• feeling sad or empty
• irregular menstruation
• irritability
• loss of interest or pleasure
• muscle pain or stiffness
• pain, cramps, or heavy bleeding
• pain in the joints
• stomach soreness or discomfort
• swollen glands
• trouble concentrating
• trouble sleeping

Less common side effects

• absent, missed, or irregular menstrual periods
• chest discomfort
• local bleeding
• shakiness in the legs, arms, hands, or feet
• stopping of menstrual bleeding
• trembling or shaking of the hands or feet

For healthcare professionals

Applies to natalizumab: intravenous concentrate.

Ocular adverse events

• Frequency not reported: Acute retinal necrosis (ARN), blindness, decreased visual acuity, redness, eye pain^[Ref]

Nervous system

• Very common (10% or more): Headache (38%)
• Common (1% to 10%): Vertigo, somnolence, tremor, dizziness
• Uncommon (0.1% to 1%): Progressive multifocal leukoencephalopathy (PML)
• Frequency not reported: Tremor^[Ref]

Respiratory

• Very common (10% or more): Upper respiratory tract infection (22%), lower respiratory tract infection (17%)
• Common (1% to 10%): Pharyngolaryngeal pain, cough, sinusitis, nasopharyngitis^[Ref]

Psychiatric

• Very common (10% or more): Depression (19%)^[Ref]

Gastrointestinal

• Very common (10% or more): Nausea (17%), gastroenteritis (11%), abdominal discomfort (11%), diarrhea (10%)
• Common (1% to 10%): Dyspepsia, constipation, flatulence, aphthous stomatitis, tooth infection, tonsillitis
• Frequency not reported: Vomiting^[Ref]

Immunologic

• Very common (10% or more): Influenza-like illness (12%)
• Common (1% to 10%): Herpes, tonsillitis, viral infection, immunogenicity^[Ref]

Hepatic

• Common (1% to 10%): Abnormal liver function test
• Postmarketing reports: Serious liver injuries, increased liver enzymes, hyperbilirubinemia^[Ref]

Other

• Very common (10% or more): Fatigue (27%)
• Common (1% to 10%): Tooth infections, toothache, rigors
• Frequency not reported: Flushing, feeling cold, pyrexia^[Ref]

Local

• Frequency not reported: Localized hypersensitivity reactions^[Ref]

Genitourinary

• Very common (10% or more): Urinary tract infection (21%), vaginitis (10%)
• Common (1% to 10%): Irregular menstruation, dysmenorrhea, amenorrhea, ovarian cyst, urinary incontinence, urinary urgency/frequency^[Ref]

Musculoskeletal

• Very common (10% or more): Arthralgia (19%), pain in extremity (16%), back pain (12%)
• Common (1% to 10%): Rigors, muscle cramp, joint swelling^[Ref]

Dermatologic

• Very common (10% or more): Rash (12%)
• Common (1% to 10%): Dermatitis, pruritus, night sweats, dry skin, urticaria^[Ref]

Hypersensitivity

• Common (1% to 10%): Immediate or delayed hypersensitivity reactions, seasonal allergy
• Frequency not reported: anaphylaxis/anaphylactoid reaction^[Ref]

Hematologic

• Rare (less than 0.1%): Anemia, hemolytic anemia^[Ref]

Metabolic

• Common (1% to 10%): Weight increased, weight decreased, peripheral edema^[Ref]

Cardiovascular

• Common (1% to 10%): Chest discomfort^[Ref]

Frequently asked questions

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Further information

Natalizumab side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.

Medical Disclaimer