If you’re looking at treatment options for multiple sclerosis (MS), your doctor might suggest Tysabri (natalizumab).

Tysabri is a prescription medication that’s used to treat MS in certain adults. Specifically, Tysabri is used to treat:

  • Relapsing-remitting MS (RRMS). RRMS involves periods of relapse (when symptoms return or worsen) and periods of remission (when symptoms lessen or go away).
  • Active secondary progressive MS (SPMS). With active SPMS, symptoms continue to worsen over time.
  • Clinically isolated syndrome (CIS). With CIS, a person has an episode of MS-like symptoms for 24 hours or more. CIS can progress to MS, but this doesn’t always happen.

MS is a condition that affects your nerves. With MS, your body’s own immune system attacks the protective covering of your nerves. This causes symptoms such as loss of coordination, vision changes, or tingling and numbness.

Tysabri is available as a solution that a healthcare professional gives you as an infusion into your vein. This means that the drug is injected through a needle over a period of time.

The active ingredient in Tysabri is natalizumab, which is a biologic. Biologics are made from parts of living organisms.

This article give details on Tysabri and its use in treating MS. You can alsosee this in-depth article for more information about Tysabri and its other uses.

Tysabri works to treat certain types of multiple sclerosis (MS) in adults. For more information about the types of MS that Tysabri treats, see the “Who is Tysabri prescribed for?” section below.

How does Tysabri work?

It isn’t known exactly what Tysabri’s mechanism of action is for treating MS. (“Mechanism of action” means how a drug works.)

It’s thought that the drug blocks inflammatory cells from approaching the brain or spinal cord. By blocking these cells from entering this area of the body, they may not be able to attack the nerves. This can reduce symptoms of MS.

For more information on how Tysabri may work, see the manufacturer’s website.

How long does it take to work?

Although Tysabri begins working after you get your first dose, you may not feel its effects right away. This is because it works by preventing relapses (periods when symptoms return or worsen). Instead, you may notice fewer relapses over time.

Below are answers to some frequently asked questions about using Tysabri to treat multiple sclerosis (MS).

Is Tysabri used to treat progressive MS?

No, Tysabri shouldn’t be used to treat progressive MS. It isn’t approved by the Food and Drug Administration (FDA) for this use. Progressive MS is also called primary progressive MS (PPMS). People with this form of MS have worsening symptoms from the beginning. They don’t have any periods of remission (times when symptoms ease). Instead, PPMS continues to worsen over time.

Tysabri is approved to treat active secondary progressive MS (SPMS). This is a condition that starts out as relapsing-remitting MS (RRMS), in which symptoms may get worse and then better again. RRMS may progress to SPMS, which means that your symptoms continue to get worse over time.

Currently, more information is needed on whether Tysabri is a safe and effective treatment for PPMS. If you have PPMS, talk with your doctor about the best treatment options for you.

Is Tysabri or Ocrevus more effective for treating MS?

It depends. Tysabri and Ocrevus are effective treatment options for certain types of MS. Both drugs are used to treat the following conditions. (For more information about these conditions, see the “Who is Tysabri prescribed for?” section below.)

  • RRMS
  • active SPMS
  • clinically isolated syndrome

In addition, Ocrevus can be used to treat PPMS.

Consider asking your doctor whether Tysabri or Ocrevus may be a better treatment option for you. These medications have different dosing schedules and different side effects. Your doctor might recommend one drug over the other based on other medical conditions you may have or other medications you may take.

See this in-depth article for more information about Tysabri. For more information about Ocrevus, see this article.

Could Tysabri make my MS worse?

No, Tysabri shouldn’t make your MS worse. Studies have shown this medication to be effective for treating certain types of MS. (For details, see the “Who is Tysabri prescribed for?” section below.)

If you’re receiving Tysabri and you stop treatment, you may have worsening MS symptoms. This is because the drug was working to decrease relapses (periods when symptoms return or worsen). Stopping Tysabri treatment may cause your symptoms to come back or worsen.

If you would like to stop Tysabri treatment, talk with your doctor about the best way to do so.

It’s also important to know that Tysabri won’t cure MS. At this time, there is no cure for the condition. But if your symptoms aren’t managed by Tysabri, the drug may not be the right treatment option for you.

If you feel that your symptoms are worsening or staying the same during Tysabri treatment, talk with your doctor. They may recommend a different medication for you.

Tysabri is used to treat certain types of multiple sclerosis (MS) in adults. (For details, see the “Who is Tysabri prescribed for?” section below.)

MS is a type of autoimmune disease, which means that your immune system attacks your own body. With MS, your immune system attacks the covering of your nerves, called the myelin sheath. This can disrupt communication between your brain and spinal cord and the rest of your body.

What are the symptoms of MS?

MS may cause many different symptoms, including:

Who is Tysabri prescribed for?

Tysabri is used to treat certain forms of MS in adults. Specifically, this medication is approved to treat:

  • Relapsing-remitting MS (RRMS). RRMS involves periods of relapse (when symptoms return or worsen) and periods of remission (when symptoms lessen or go away).
  • Active secondary progressive MS (SPMS). With active SPMS, symptoms continue to worsen over time.
  • Clinically isolated syndrome (CIS). With CIS, a person has an episode of MS-like symptoms for 24 hours or more. CIS can progress to MS, but this doesn’t always happen.

Tysabri isn’t approved for use in children. It isn’t known at this time if the drug may be a safe and effective treatment option for children.

Tysabri has been shown to be an effective treatment option in studies of people with certain types of multiple sclerosis (MS).* In fact, American Academy of Neurology guidelines recommend it as an effective treatment option for MS.

Tysabri won’t cure MS. At this time, there is no cure for the condition. Instead, Tysabri works by preventing relapses (periods when symptoms return or worsen) and helping manage your symptoms.

For more information on the effectiveness of Tysabri, see the manufacturer’s website. You can also talk with your doctor or pharmacist about how well this medication may work for you.

* For more information about the types of MS that Tysabri treats, see the “Who is Tysabri prescribed for?” section above.

You may wonder how Tysabri is given and how often you need a dose. Read on for details about Tysabri’s dosage and how the medication is given.

What is the typical dosage for Tysabri?

For treating multiple sclerosis (MS), the usual dosage of Tysabri is 300 milligrams (mg), which you’ll receive once every 4 weeks.

Note: Tysabri has other uses in addition to treating MS. The dosage may be different for these other uses. To learn more, talk with your doctor.

How will I receive Tysabri?

A healthcare professional will give you Tysabri as an infusion into your vein. This means that the drug is injected through a needle over a period of time. Your infusion of Tysabri will likely be given over the course of 1 hour.

You can receive Tysabri infusions only in certain treatment centers. This is because Tysabri may cause progressive multifocal leukoencephalopathy (PML).

Although PML is a rare side effect, it could be life threatening. As a result, Tysabri is available only through a special program called a Risk Evaluation and Mitigation Strategy (REMS) program. The specific REMS program for Tysabri is called the Tysabri Outreach: Unified Commitment to Health (TOUCH) program.

The purpose of the TOUCH program is to make sure that you and your doctor understand the risks of Tysabri. In addition, the program requires that you be monitored for signs and symptoms of PML during treatment. Because of these requirements, the TOUCH program has certain restrictions:

  • Only certain doctors can prescribe Tysabri.
  • Only certain pharmacies can dispense the medication.
  • You can only go to certain infusion centers to receive your medication.

To find a Tysabri treatment center near you, see this website.

How often will I receive Tysabri infusions?

You’ll likely receive a Tysabri dose of 300 mg once every 4 weeks.

Using Tysabri to treat multiple sclerosis (MS)* may cause side effects in some people. These side effects can be mild or serious.

The lists below include some of the main side effects that have been reported in people using Tysabri. For information about other possible side effects of the drug, talk with your doctor or pharmacist.

You can also learn more about side effects from this in-depth article or from the Tysabri medication guide.

* Tysabri is also approved to treat other conditions. It’s important to note that side effects from Tysabri may differ depending on the condition it’s treating.

What are Tysabri’s mild side effects?

You may have mild side effects from using Tysabri to treat your MS. Examples of mild side effects include:

In many cases, mild side effects from the drug can be temporary. Some side effects may be easy to manage, too. But if side effects don’t seem to be easing, or if they bother you or become severe, talk with your doctor or pharmacist.

What are Tysabri’s serious side effects?

Although less common, Tysabri can cause serious side effects. Examples include:

* Tysabri has a boxed warning for this side effect. This is the most serious warning from the Food and Drug Administration (FDA). To learn more, see the “What should I know before using Tysabri?” section below.

Call your doctor right away if you have any serious side effects while using Tysabri. If the side effects seem life threatening or if you think you’re having a medical emergency, call 911 or your local emergency number immediately.

Before you use Tysabri, there’s some important information to keep in mind. The drug may not be a safe option for you if you have certain medical conditions or other factors that affect your health. Some of these are mentioned below.

Boxed warning: Progressive multifocal leukoencephalopathy

Tysabri has a boxed warning. This is 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 has a boxed warning for risk of progressive multifocal leukoencephalopathy (PML). PML is a rare but life threatening side effect that can occur from Tysabri. Symptoms of this condition include:

Due to the risk of PML, Tysabri is available only through a special program called a Risk Evaluation and Mitigation Strategy (REMS) program. The specific REMS program for Tysabri is called the Tysabri Outreach: Unified Commitment to Health (TOUCH) program. For more information about this program, see the “How will I receive Tysabri?” section above.

If you develop any symptoms of PML, contact your doctor right away or go to the nearest emergency room.

What other warnings should I know about?

In addition to its boxed warning for PML, Tysabri has other warnings. If any of the following medical conditions or other health factors apply to you, talk with your doctor before using Tysabri.

  • You have a history of herpes infections.
  • You have any conditions that affect your immune system, such as HIV or cancer.
  • You have a current infection.
  • You’re pregnant or breastfeeding.
  • You’ve had an allergic reaction to the drug or any of its ingredients.

The price of Tysabri depends on several factors. These can include your treatment plan, your insurance plan, the pharmacy you use, and your location. The price also depends on the cost of the appointment to receive doses of Tysabri from a healthcare professional.

For estimates of how much Tysabri costs, visit WellRx.com.

At this time, Tysabri is only available as a brand-name drug.

Talk with your doctor about using Tysabri for multiple sclerosis (MS). They can work with you to determine if Tysabri might be a good fit for you.

Here are some examples of questions you may want to ask your doctor:

  • How should I treat side effects that I have from receiving Tysabri for MS?
  • What should I do if I become pregnant during Tysabri treatment?
  • Is it safe for me to use Tysabri along with my other medications?
  • Do my other medical conditions increase my risk of side effects?

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Disclaimer: Healthline 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.