Tysabri's Dosage: What to Know

Medically Reviewed By Amber R. Watson, PharmD

Doctors prescribe Tysabri (natalizumab) for certain conditions, such as Crohn’s disease. It’s a solution that a healthcare professional administers by intravenous (IV) infusion. You will typically receive it once every four weeks, and each infusion lasts about an hour. The Food and Drug Administration (FDA) has approved Tysabri to treat the following conditions in adults:

For details about these conditions, see this comprehensive article about Tysabri.

It’s a biologic drug, and it’s not available in a biosimilar form.*

In this article, you’ll find information about Tysabri’s dosage and details on how to use the drug. For a comprehensive overview of Tysabri, view this article.

* A biosimilar medication is a drug that’s similar to a brand-name biologic drug (the parent drug).

Finding a healthcare professional

If you’re interested in using Tysabri, search here to find a doctor who might prescribe it.

This article describes typical recommended dosages for Tysabri. These dosages are provided by the drug’s manufacturer.

Your doctor will prescribe the dosage of Tysabri that’s best for you.

This drug has a boxed warning Trusted Source PubMed Central Highly respected database from the National Institutes of Health Go to source , the most serious warning from the Food and Drug Administration (FDA). A boxed warning alerts doctors and patients about drug effects that may be dangerous.

Tysabri increases the risk of progressive multifocal leukoencephalopathy (PML), which is a serious brain infection. PML is caused by a virus and can lead to severe disability and even death.

Symptoms of PML can vary but may include problems with memory, thinking, coordination, and vision. These symptoms may worsen over time. Doctors will watch for symptoms of PML during Tysabri treatment. They’ll also watch for PML symptoms for at least 6 months after treatment ends.

If you have symptoms of PML with Tysabri, contact your doctor right away.

Due to the risk of PML, Tysabri is available only through a program called Tysabri Outreach: Unified Commitment to Health (TOUCH). This is a type of Risk Evaluation and Mitigation Strategy (REMS) Trusted Source Food and Drug Administration (FDA) Governmental authority Go to source program. The FDA created REMS to make sure doctors prescribe certain drugs safely.

Your doctor can tell you more about PML and the Tysabri TOUCH Prescribing Program.

Tysabri: Dosage

This section describes the commonly recommended dosage for Tysabri. However, your doctor will prescribe the Tysabri dosage that’s right for you.

Tysabri’s form and strength

Tysabri comes as a solution containing 300 milligrams per 15 milliliters (mg/mL) of the drug. Once a healthcare professional has prepared the solution correctly, they will administer it by intravenous (IV) infusion.

Typical recommended dosage

Tysabri has the same recommended dosage for each condition it is approved to treat in adults. These include Crohn’s disease, relapsing-remitting multiple sclerosis (MS), active secondary progressive MS, and clinically isolated syndrome (CIS).*

* CIS sometimes indicates the start of MS, but not everyone who has had CIS develops MS.

Adult’s dosage

The overview below shows Tysabri’s recommended dosage for adults. Your doctor will prescribe the dosage of Tysabri that’s right for your condition.

  • IV infusion dosage: 300 mg, to be infused over 1 hour
  • Frequency: every 4 weeks

Length of treatment

Doctors typically prescribe Tysabri as a long-term treatment. You’ll likely receive it long term if you and your doctor feel it’s safe and effective for your condition.

Tysabri: Common questions about dosage

The common questions below relate to Tysabri’s dosage.

Is there a Tysabri 300-mg dose?

Yes, the recommended dose of Tysabri is 300 milligrams (mg). You’ll receive it as an intravenous (IV) infusion every 4 weeks.

For more information about Tysabri’s dosage and its administration, talk with your doctor or pharmacist.

Are there any drug interactions that would cause a dosage adjustment of Tysabri?

No, none would require a dosage adjustment of Tysabri.

Even so, Tysabri can interact with certain other drugs, such as immunosuppressants and corticosteroids. This interaction can increase your risk of infection. However, it doesn’t require a dosage adjustment of Tysabri. Instead, if you take one of these drugs, doctors might recommend stopping it before you receive Tysabri.

Tell your doctor about all medications you take. If you have questions about using Tysabri with other drugs, ask your doctor or pharmacist.

Does Tysabri have a recommended dosing schedule?

Yes, the recommended dosing schedule for Tysabri is an IV infusion every 4 weeks. Tysabri is meant for long-term, extended dosing. This is because Tysabri can take up to 12 weeks to be fully effective.

For questions about the dosing schedule or extended dosing of Tysabri, talk with your doctor.

Tysabri: How it’s administered

Tysabri comes as a solution for intravenous (IV) infusion that a healthcare professional injects into your vein. You’ll receive it at a hospital, infusion center, or clinic.

Due to certain risks, Tysabri is available only through a program called Tysabri Outreach: Unified Commitment to Health (TOUCH). This is a type of Risk Evaluation and Mitigation Strategy (REMS) Trusted Source Food and Drug Administration (FDA) Governmental authority Go to source program. The FDA created REMS to make sure doctors prescribe certain drugs safely. For more information, see the “FDA warning: Risk of progressive multifocal leukoencephalopathy (PML)” section above.

Tysabri: Missing a dose

If you miss an appointment to receive your Tysabri dose, get it rescheduled right away. Call the hospital, infusion center, or clinic. They can schedule a new appointment and adjust your dosing schedule if necessary.

Tysabri: What to discuss with your doctor

Talk with your doctor or pharmacist for additional information about Tysabri’s dosage. The dosages presented in this article are typical dosages that the drug’s manufacturer provides.

In addition to discussing Tysabri with your doctor, you may find the following articles helpful in learning more.

Disclaimer: Healthgrades has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.


Medical Reviewer: Amber R. Watson, PharmD
Last Review Date: 2023 Sep 14
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