Natalizumab: uses, dosing, side effects & brands
Natalizumab is a medicine sold in the U.S. under one brand, for crohn disease and multiple sclerosis. Below: what the FDA label says, every product that contains it, what the pills look like, and its recall record.
Key facts
- Treats
- Crohn Disease and Multiple Sclerosis
- Available as
- Injectable
- Sold as
- Tysabri
- Prescription?
- Prescription only
- Generic available?
- Not in our catalog
- Boxed warning
- Boxed warning
How natalizumab is dosed
From the FDA label for Tysabri (application BLA125104). Other natalizumab products — different forms, different strengths — are dosed differently. Follow the label for the one you were prescribed.
300 mg infused intravenously over one hour, every four weeks. Do not give as an intravenous push or bolus ( 2.1 , 2.2 ) TYSABRI solution must be administered within 48 hours of preparation ( 2.3 ) Observe patients during all infusions. Post-infusion, for the first 12 infusions, observe patients for one hour after the infusion is complete. For patients who have received 12 infusions without evidence of a hypersensitivity reaction, observe patients post-infusion for the 13th and subsequent infusions according to clinical judgment. ( 2.4 ) In CD, discontinue in patients that have not experienced therapeutic benefit by 12 weeks of induction therapy, and in patients that cannot discontinue chronic concomitant steroids within six months of starting therapy ( 2.2 ) 2.1 Multiple Sclerosis (MS) Only prescribers registered in the MS TOUCH ® Prescribing Program may prescribe TYSABRI for multiple sclerosis [ see Warnings and Precautions ( 5.2 ) ]. The recommended dose of TYSABRI for multiple sclerosis is 300 mg intravenous infusion over one hour every four weeks. 2.2 Crohn's Disease (CD) Only prescribers registered in the CD TOUCH ® Prescribing Program may prescribe TYSABRI for Crohn's disease [ see Warnings and Precautions ( 5.2 ) ]. The recommended dose of TYSABRI for Crohn's disease is 300 mg intravenous infusion over one hour every four weeks. TYSABRI should not be used with…
Natalizumab side effects
The following serious adverse reactions are described below and elsewhere in the labeling: Progressive Multifocal Leukoencephalopathy (PML) [see Warnings and Precautions ( 5.1 )] Herpes Infections [see Warnings and Precautions ( 5.3 )] Hepatotoxicity [see Warnings and Precautions ( 5.4 )] Hypersensitivity/Antibody Formation [see Warnings and Precautions ( 5.5 )] Immunosuppression/Infections [see Warnings and Precautions ( 5.6 )] Hematological Abnormalities [see Warnings and Precautions ( 5.8 )] Most common adverse reactions (incidence ≥ 10%): MS - headache, fatigue, arthralgia, urinary tract infection, lower respiratory tract infection, gastroenteritis, vaginitis, depression, pain in extremity, abdominal discomfort, diarrhea NOS, and rash ( 6.1 ) CD - headache, upper respiratory tract infections, nausea, and fatigue ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Biogen at 1-800-456-2255 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch . 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. The most common adverse reactions (incidence ≥ 10%) were headache and fatigue in both the multiple sclerosis (MS) and Crohn's disease (CD)…
Who shouldn’t take natalizumab
TYSABRI is contraindicated in patients who have or have had progressive multifocal leukoencephalopathy (PML) [ see Warnings and Precautions ( 5.1 ) ]. TYSABRI is contraindicated in patients who have had a hypersensitivity reaction to TYSABRI. Observed reactions range from urticaria to anaphylaxis [ see Warnings and Precautions ( 5.5 ) ]. Patients who have or have had PML ( 4 ) Patients who have had a hypersensitivity reaction to TYSABRI ( 4 , 5.3 )
Natalizumab drug interactions
Because of the potential for increased risk of PML and other infections, Crohn's disease patients receiving TYSABRI should not be treated with concomitant immunosuppressants (e.g., 6-mercaptopurine, azathioprine, cyclosporine, or methotrexate) or inhibitors of TNF-α, and corticosteroids should be tapered in those patients with Crohn's disease who are on chronic corticosteroids when they start TYSABRI therapy [ see Indications and Usage ( 1.2 ), Warnings and Precautions ( 5.1 , 5.6 ) ]. Ordinarily, MS patients receiving chronic immunosuppressant or immunomodulatory therapy should not be treated with TYSABRI [ see Indications and Usage ( 1.1 ), Warnings and Precautions ( 5.1 , 5.6 ) ].
Every natalizumab product we track (1)
Same active ingredient — different manufacturer, form, price and FDA recall record. That last one is what our independent score measures.
Only one: Tysabri.
Natalizumab and breastfeeding
From LactMed, the US National Library of Medicine’s Drugs and Lactation Database — quoted, not rewritten.
Full LactMed record for natalizumab: levels in milk, effects in breastfed infants, and the drugs it would consider insteadMeasurable, but low, amounts of natalizumab are excreted into breastmilk in some women. The peak level in breastmilk often occurs in the first week after the dose, but might be as long as 6 months with repeated doses. Limited information indicates that the drug is not measurable in the serum of breastfed infants. Most expert guidelines consider breastfeeding with natalizumab to be acceptable. Waiting for at least 2 weeks postpartum to resume therapy may minimize transfer to the infant.
National Institute of Child Health and Human Development, record revised July 15, 2026. LactMed states its information is not a substitute for professional judgement.
What people report to the FDA about natalizumab
The FDA Adverse Event Reporting System (FAERS) collects reports from patients and clinicians. It holds 2,964 reports naming natalizumab, and the FDA flagged 54% of those reports as serious. The effects reported most often — leaving out reports about overdose, misuse or the condition being treated, which dominate the raw list for common medicines:
- fatigue383 reports
- headache341 reports
- multiple sclerosis relapse177 reports
- multiple sclerosis172 reports
- asthenia158 reports
- influenza like illness146 reports
- nausea142 reports
- urinary tract infection127 reports
Read these as a signal, not a rate. A report does not mean natalizumab caused the effect — anyone can file one, and many describe people taking several medicines for several conditions. Crucially there is no denominator: FAERS does not record how many people took the drug, so these counts cannot be turned into “X% of patients” — a bigger number often just means a more widely used or more talked-about drug. Duplicates exist, and publicity drives reporting. For what is actually established, read the FDA label section above.
Source: openFDA drug/event (FAERS), retrieved July 25, 2026.
Related calculators
Frequently asked questions
What is natalizumab?
Tysabri (Natalizumab) is a medication used to treat Crohn Disease, Multiple Sclerosis.
Can you take natalizumab with other medicines?
It depends on the medicine. We check it against the FDA labels rather than guessing: our interaction checker searches each drug's own label for the other and quotes what it says, naming the section it came from. Run natalizumab against whatever else you take — and remember that a label not naming a drug is not the same as that combination being safe.
What forms does natalizumab come in?
Across the brands we track, natalizumab is currently marketed as injectable, per the FDA's National Drug Code Directory. Each form is dosed differently — follow the label for the exact product you were prescribed.
Is there a generic natalizumab?
We do not currently list a generic-labelled natalizumab product. That does not always mean none exists — it means none appears under a generic name in the FDA data we track. Ask your pharmacist.
Cite this page
- APA
- pharmaranks. (2026, July 24). Natalizumab: uses, dosing, side effects & brands. https://pharmaranks.com/drugs/natalizumab
- MLA
- “Natalizumab: uses, dosing, side effects & brands.” pharmaranks, 24 July 2026, https://pharmaranks.com/drugs/natalizumab.
We summarise public FDA and NIH sources — for a clinical claim, cite the primary source we link to as well.
Sources: FDA openFDA drug label, National Drug Code Directory, and Enforcement (recall) database. This page reproduces public FDA data and is not medical advice. Dosing is set by your prescriber.
Read the full FDA label for natalizumab on DailyMed (NIH) ↗ — including its boxed warning in full.