Natalizumab
Pronunciation: (nah-ta-LIZ-ue-mab).
- Generic name
- natalizumab
- Brand names
- Tysabri, NataliRel, Natzumab
- Drug class
- Monoclonal antibody; Immunomodulator
Availability and supply rules vary by country
Trade names by country: United States · Canada
Australia: · Full directory
What natalizumab is and how it works
Uses, formulations, monitoring, and supply rules can differ by patient, product, and country. Follow the exact local product information and professional advice.
Mechanism of action: how natalizumab works
Natalizumab is a humanized monoclonal antibody that selectively binds to the α4-subunit of integrins (α4β1 and α4β7) on the surface of leukocytes, except neutrophils. By blocking these integrins, natalizumab inhibits the adhesion and migration of leukocytes across the blood-brain barrier and into inflamed tissue, thereby reducing inflammation in the central nervous system (CNS) in multiple sclerosis and in the gastrointestinal tract in Crohn’s disease. (1)
What natalizumab is used for
Relapsing forms of multiple sclerosis (MS)
Monotherapy for clinically isolated syndrome, relapsing-remitting disease, and active secondary progressive disease in adults, generally after an inadequate response to, or inability to tolerate, an alternative MS therapy, given the PML risk. (2)
Moderately-to-severely active Crohn's disease
For inducing and maintaining clinical response and remission in adults with evidence of inflammation who have not responded well enough to, or cannot tolerate, conventional therapy and a TNF-alpha inhibitor. Must not be combined with immunosuppressants or TNF-alpha inhibitors. (2)
Before taking natalizumab
Do not take / not appropriate for
- a history of PML, current serious infections, and hypersensitivity to natalizumab. (Contraindication) (2)
- Screen for latent infections before starting therapy. (Contraindication) (2)
Tell your clinician about
(2)How to take natalizumab
- General Instructions: Natalizumab is administered as an intravenous infusion by a healthcare professional, typically every 4 weeks.. Adult Dosing: The recommended dose for adults is 300 mg by IV infusion over approximately 1 hour every 4 weeks.. Pediatric Dosing: Safety and efficacy in children under 18 years have not been established; use in pediatric patients is not routinely recommended.. Administration: Infusions are given in a clinic or hospital setting. Patients are monitored during and after the infusion for signs of allergic reactions or side effects.. When To Stop: Seek immediate medical attention if PML is suspected, if a severe allergic reaction occurs, or if a serious infection develops; let the clinical team decide right away whether to continue or stop treatment.. Storage: Natalizumab vials should be stored in a refrigerator (2°C–8°C/36°F–46°F) and protected from light. Do not freeze.
- This page does not provide a dose calculator. Dosing must follow the prescriber, pharmacist, or product label.
Procedures and treatment changes
Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (2)
Missed dose
If you miss an infusion, contact your healthcare provider as soon as possible to reschedule. Do not attempt to self-administer this medicine or take an extra dose.
Overdose
There is limited experience with overdose. In case of suspected overdose, seek immediate medical attention. Supportive care and monitoring are recommended. (2)
Side effects
Side effects and their urgency vary; report severe, persistent, or concerning symptoms to a healthcare professional.
Headache
Incidence: Common (>=10%) in both MS and Crohn's disease clinical trials
Fatigue
Incidence: Common (>=10%) in both MS and Crohn's disease clinical trials
Joint pain (arthralgia)
Incidence: Common (>=10%) in MS clinical trials
Urinary tract infection
Incidence: Common (>=10%) in MS clinical trials
Lower respiratory tract infection
Incidence: Common (>=10%) in MS clinical trials
Gastroenteritis
Incidence: Common (>=10%) in MS clinical trials
Vaginitis
Incidence: Common (>=10%) in MS clinical trials
Depression
Incidence: Common (>=10%) in MS clinical trials
Pain in an arm or leg
Incidence: Common (>=10%) in MS clinical trials
Abdominal discomfort
Incidence: Common (>=10%) in MS clinical trials
Diarrhea
Incidence: Common (>=10%) in MS clinical trials
Upper respiratory tract infection
Incidence: Common (>=10%) in Crohn's disease clinical trials
Nausea
Incidence: Common (>=10%) in Crohn's disease clinical trials
Serious warnings
FDA BOXED WARNING — serious
Symptoms: FDA BOXED WARNING: Natalizumab increases the risk of progressive multifocal leukoencephalopathy (PML), a rare brain infection that usually leads to death or severe disability. Risk is highest in people who have antibodies to the JC virus, who have been on treatment longer than 2 years, and who have previously taken an immune-suppressing medicine — having all three raises risk the most. Seek emergency medical attention immediately at the first sign of PML (such as new weakness, vision changes, confusion, or personality changes) — the clinical team will determine right away whether treatment should continue or stop. Because of this risk, natalizumab is only available through a restricted program (the TOUCH Prescribing Program) with enrolled prescribers, pharmacies, and infusion sites.
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2)
Serious, sometimes fatal, liver injury (including acute liver failure requiring transplant) has been reported with natalizumab, in some cases within days of the first dose — serious
Symptoms: Serious, sometimes fatal, liver injury (including acute liver failure requiring transplant) has been reported with natalizumab, in some cases within days of the first dose. Seek prompt medical attention for yellowing of the skin or eyes, dark urine, or unusual fatigue — let the clinician you see advise on liver testing and whether to continue treatment.
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2)
Serious infusion reactions, including anaphylaxis, occur in under 1% of patients, usually within 2 hours of starting the infusion (signs include hives, fever, rash, low blood pressure, shortness of breath, or chest pain) — serious
Symptoms: Serious infusion reactions, including anaphylaxis, occur in under 1% of patients, usually within 2 hours of starting the infusion (signs include hives, fever, rash, low blood pressure, shortness of breath, or chest pain). Treatment is stopped immediately if this occurs, and affected patients are not given natalizumab again.
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2)
Natalizumab increases the risk of PML, a rare but serious brain infection — serious
Symptoms: Natalizumab increases the risk of PML, a rare but serious brain infection. Serious allergic reactions may occur during or after infusion. May increase the risk of other infections, including herpes and respiratory infections. Use with caution in patients with a history of liver disease. Not recommended for use with other immunosuppressive or immunomodulatory therapies.
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2)
The FDA label's formal contraindications are a history of PML and a history of a hypersensitivity reaction to natalizumab — serious
Symptoms: The FDA label's formal contraindications are a history of PML and a history of a hypersensitivity reaction to natalizumab. Current serious infection is not a formal contraindication but is an important pre-treatment screening consideration — your care team will screen for active and latent infections before starting. Use with caution in patients with a history of liver disease, immunosuppression, or prior use of immunomodulatory therapies.
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2)
Interactions
| Medicine or test | Effect | Action |
|---|---|---|
| Recorded interactions | Natalizumab should not be used in combination with other immunosuppressive agents or biologics due to increased risk of infections, including PML. Inform your healthcare provider of all medications, supplements, and vaccines you are taking. Live vaccines should be avoided during and for several months after therapy. | (1) |
Pregnancy, breastfeeding, kidney/liver function, age
Pregnancy
Natalizumab can cause fetal harm. Neonatal thrombocytopenia (low platelets) and anemia have been reported in infants exposed in utero, so a complete blood count is recommended for babies born after exposure during pregnancy. The decision to continue or start treatment during pregnancy should be made together with the prescribing team, weighing the risk of untreated MS or Crohn's disease relapse against this fetal risk. (2)
Breastfeeding
Natalizumab has been detected in human breast milk; the effects on a breastfed infant are unknown. The decision to breastfeed during treatment should weigh the mother's clinical need for natalizumab against potential infant exposure, in discussion with the prescribing team. (2)
Children
Frequency: Not applicable.. Weight Based: Not recommended for pediatric use.. Max Daily Dose: Not applicable.. Max Single Dose: Not applicable.. Age Restrictions: Safety not established in children. (2)
Renal_impairment
The label does not define a specific renal or hepatic dose adjustment for natalizumab. Because of the risk of serious, sometimes fatal liver injury, anyone with a history of liver disease requires closer monitoring and individualized decision-making by the prescribing team; there is no defined numeric renal-impairment adjustment. (2)
Hepatic_impairment
The label does not define a specific renal or hepatic dose adjustment for natalizumab. Because of the risk of serious, sometimes fatal liver injury, anyone with a history of liver disease requires closer monitoring and individualized decision-making by the prescribing team; there is no defined numeric renal-impairment adjustment. (2)
Monitoring
(2)Storage
Natalizumab vials are stored by healthcare staff in a refrigerator (2-8C/36-46F), protected from light, not frozen, and not shaken. Patients do not store or handle this medication themselves.
Professional information
Clinician-facing context only. This section does not replace current product labeling.
General
Indication: Relapsing multiple sclerosis; moderately-to-severely active Crohn's disease
Dose summary: 300 mg by IV infusion over approximately 1 hour, every 4 weeks. Only administered through the TOUCH Prescribing Program (REMS) by enrolled prescribers/infusion sites. Anti-JCV antibody status tested before starting and roughly every 6 months thereafter (allow 2 weeks after plasma exchange, or 6 months after IVIG, before testing to avoid false results). Clinical follow-up recommended at 3 and 6 months after the first infusion, then every 6 months, and roughly 6 months after any discontinuation.
Renal context: No specific renal or hepatic dose-adjustment schedule is defined in the label; dosing is individualized by the prescribing team, with closer monitoring for anyone with liver disease given the hepatotoxicity risk. (1) (2)
Frequently asked questions
What is natalizumab used for?
Natalizumab is used to treat relapsing forms of multiple sclerosis (MS) and moderate to severe Crohn’s disease in adults who have not responded well to other treatments.
How is natalizumab administered?
It is given as an intravenous (IV) infusion by a healthcare professional, usually every 4 weeks.
What are the most serious risks of natalizumab?
The most serious risk is progressive multifocal leukoencephalopathy (PML), a rare brain infection. Other risks include severe allergic reactions and increased risk of infections.
Can I receive vaccines while on natalizumab?
You should avoid live vaccines during treatment and for several months after stopping natalizumab. Discuss all vaccines with your healthcare provider.
Is natalizumab safe during pregnancy or breastfeeding?
The safety of natalizumab during pregnancy and breastfeeding is not fully established. Discuss risks and benefits with your healthcare provider.
What should I do if I miss a dose?
Contact your healthcare provider as soon as possible to reschedule your infusion. Do not try to self-administer this medicine or take an extra dose.
How will my doctor monitor me during natalizumab treatment?
Your doctor will monitor for signs of infection, perform regular neurological assessments, and may order MRI scans to check for early signs of PML.
What happens if I take too much Natalizumab?
If you suspect an overdose of Natalizumab, it is crucial to seek immediate emergency medical attention. While specific overdose symptoms for Natalizumab are not well-defined, any unusual or severe reactions should be reported to a healthcare professional without delay. Prompt medical evaluation can help manage potential adverse effects and ensure your safety.
Can I drink alcohol while taking Natalizumab?
While there are no direct contraindications for alcohol consumption with Natalizumab, it is generally advisable to exercise caution. As an immunomodulator, Natalizumab can affect your immune system. Excessive alcohol intake can also suppress the immune system and potentially exacerbate certain side effects or underlying conditions. Consult your healthcare provider for personalized advice regarding alcohol consumption.
Is Natalizumab safe during pregnancy?
Natalizumab's safety during pregnancy falls under a specific category, and its use should be carefully considered. It is imperative to consult your doctor if you are pregnant, planning to become pregnant, or breastfeeding. Your healthcare provider can assess the potential risks and benefits, discuss alternative treatments, and help you make an informed decision regarding Natalizumab use during pregnancy.
What is the mechanism of action of natalizumab?
Natalizumab is a humanized monoclonal antibody that selectively binds to the α4-subunit of integrins (α4β1 and α4β7) on the surface of leukocytes, except neutrophils. By blocking these integrins, natalizumab inhibits the adhesion and migration of leukocytes across the blood-brain barrier and into inflamed tissue, thereby reducing inflammation in the central nervous system (CNS) in multiple sclerosis and in the gastrointestinal tract in Crohn’s disease. (1)
What is the generic name of Natalizumab?
The generic name is natalizumab. It is sold under brand names including Tysabri, NataliRel, Natzumab.
What class of drug is natalizumab?
Natalizumab is classed as: Monoclonal antibody; Immunomodulator.
References
- Natalizumab clinician-authored medicine recordMedGuideGlobal clinician-authored medicine record (internal database) · Global (internal) · accessed 2026-08-06 · source 1
- TYSABRI (natalizumab) injection, for intravenous useU.S. National Library of Medicine, DailyMed · United States · dated 2026 · accessed 2026-08-06 · source 2
- TYRUKO (NATALIZUMAB-SZTN) INJECTION [SANDOZ INC] — US prescribing information (DailyMed SPL)U.S. National Library of Medicine (DailyMed) · US · accessed 2026-08-14 · source 3
- Natalizumab Injection — patient drug information (MedlinePlus)U.S. National Library of Medicine (MedlinePlus) · US · accessed 2026-08-14 · source 4
- TYSABRI — FDA approval record (Drugs@FDA BLA125104)U.S. Food and Drug Administration · US · accessed 2026-08-14 · source 5
- natalizumab — RxNorm normalized drug concept (RXCUI 354770)U.S. National Library of Medicine (RxNorm) · US · accessed 2026-08-14 · source 6
Brand names by country
Single-ingredient natalizumab names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.
Priority countries
United States
- TYRUKO300 mg5mL · sandoz inc
- TYSABRI300 mg5mL · biogen inc.
Canada
- TYSABRI