If you have multiple sclerosis (MS) or Crohn’s disease, your doctor may suggest treatment with Tysabri. It’s a prescription medication used in certain adults with MS or Crohn’s disease.

Tysabri is used to treat these conditions in certain situations. To learn more, see the “What is Tysabri used for?” section below.

Tysabri basics

Tysabri contains the active ingredient natalizumab. (An active ingredient is what makes a drug work). Tysabri is a biologic medication. A biologic is made from parts of living organisms.

Tysabri is not available in a biosimilar form. (Biosimilars are like generic drugs. But unlike generics, which are made for non-biologic drugs, biosimilars are made for biologic drugs.) Instead, Tysabri is only available as a brand-name drug.

Tysabri comes as a liquid solution that’s given as an intravenous (IV) infusion (an injection into a vein over a period of time). You’ll receive Tysabri doses at your doctor’s office or another healthcare facility.

In this article, we describe Tysabri’s side effects, cost, uses, and more.

Like most drugs, Tysabri may cause mild or serious side effects. The lists below describe some of the more common side effects that Tysabri may cause. These lists don’t include all possible side effects.

Keep in mind that side effects of a drug can depend on:

  • your age
  • other health conditions you have
  • other medications you take

Your doctor or pharmacist can tell you more about the potential side effects of Tysabri. They can also suggest ways to help reduce side effects.

Mild side effects

Here’s a list of some of the mild side effects that Tysabri can cause. To learn about other mild side effects, talk with your doctor or pharmacist, or read Tysabri’s prescribing information.

Mild side effects that can occur with Tysabri include:

Mild side effects of many drugs may go away within a few days to a couple of weeks. But if they become bothersome, talk with your doctor or pharmacist.

* To learn more about this side effect, see the “Allergic reaction” section below.

Serious side effects

Serious side effects from Tysabri can occur, but they aren’t common. If you have serious side effects from Tysabri, call your doctor right away. But if you think you’re having a medical emergency, you should call 911 or your local emergency number.

Serious side effects of Tysabri that have been reported include:

* For more information, see the “Boxed warning” section at the beginning of this article.
† To learn more about this side effect, see the “Allergic reaction” section below.

SUICIDE PREVENTION

If you think someone is at immediate risk of self-harm or hurting another person:

  • Call 911 or your local emergency number.
  • Stay with the person until help arrives.
  • Remove any guns, knives, medications, or other things that may cause harm.
  • Listen, but don’t judge, argue, threaten, or yell.

If you or someone you know is considering suicide, get help from a crisis or suicide prevention hotline. Try the National Suicide Prevention Lifeline at 800-273-8255.

Allergic reaction

Some people may have an allergic reaction to Tysabri. However, allergic reactions were rare in Tysabri’s clinical studies.

Symptoms of a mild allergic reaction can include:

A more severe allergic reaction is rare but possible. Symptoms of a severe allergic reaction can include swelling under your skin, usually in your eyelids, lips, hands, or feet. They can also include swelling of your tongue, mouth, or throat, which can cause trouble breathing.

Call your doctor right away if you have an allergic reaction to Tysabri. But if you think you’re having a medical emergency, call 911 or your local emergency number.

Prices for prescription drugs such as Tysabri can vary depending on many factors. These factors include what your insurance plan covers. To find typical Tysabri infusion costs in your area, visit WellRx.com.

If you have questions about how to pay for your prescription, talk with your doctor or pharmacist. A suite of resources called Biogen Support Services may also be available.

Additionally, you can check out this article to learn more about saving money on prescriptions.

Find answers to some commonly asked questions about Tysabri.

Is Tysabri an immunosuppressant or a form of chemotherapy?

Tysabri isn’t a kind of chemotherapy, but it is an immunosuppressant.

Chemotherapy drugs are used to treat cancer. They work by stopping cells in your body from multiplying, especially cells that grow quickly (such as cancer cells).

Immunosuppressants such as Tysabri work differently than chemotherapy drugs. Tysabri’s mechanism of action (the way it works) is that it weakens your immune system. This can help manage symptoms of your condition, but it also raises your risk of infection.

If you have questions about how Tysabri works to treat your condition, talk with your doctor or pharmacist.

Will I have withdrawal symptoms if I stop my Tysabri treatment?

Stopping Tysabri isn’t expected to cause withdrawal symptoms. (Withdrawal symptoms are side effects that occur when you stop taking a drug that your body has become dependent on.)

But stopping Tysabri may cause symptoms of your condition to return or worsen. For this reason, it’s important to talk with your doctor if you’re interested in stopping your Tysabri treatment. Your doctor can discuss other treatment options for your condition.

Does Tysabri cause hair loss?

No, Tysabri doesn’t cause hair loss. This side effect wasn’t reported in Tysabri’s studies.

Crohn’s disease and multiple sclerosis can both trigger hair loss, and these are the conditions Tysabri treats. Also, other medications used to treat these conditions, such as teriflunomide (Aubagio), can cause hair loss.

If you’re concerned about hair loss, talk with your doctor.

Tysabri is used to treat multiple sclerosis (MS) and Crohn’s disease in adults.

Tysabri’s mechanism of action (the way it works) is that it weakens your immune system. As both MS and Crohn’s disease are believed to be caused by an overactive immune system, this helps manage symptoms of these conditions.

See below for details on each use.

Tysabri for MS

Tysabri is used to treat relapsing forms of MS. Examples include relapsing-remitting MS and active* secondary progressive MS. Tysabri is also used to treat clinically isolated syndrome, which is often an early sign of MS that occurs before an MS diagnosis.

MS is a chronic (long-term) autoimmune condition. With MS, your immune system mistakenly attacks myelin, which is a protective layer found around your nerve fibers. This makes it hard for your nervous system to function normally.

With MS, you may have periods of remission (no symptoms) and relapse (worsened symptoms).

Symptoms of MS include:

  • fatigue (low energy)
  • problems with walking, balance, or coordination
  • vision problems, such as blurry vision
  • slurred speech
  • chronic pain

It’s important to note that Tysabri should not be used with other immunosuppressants to treat MS. Examples of these drugs include azathioprine (Azasan), methotrexate (Trexall, others), and cyclophosphamide (Cytoxan).

Using Tysabri with immunosuppressants could increase the risk of progressive multifocal leukoencephalopathy (PML) as a side effect. To learn more, see the “Boxed warning” section at the beginning of this article.

* “Active” means the condition is causing symptoms.

Tysabri for Crohn’s disease

Tysabri is used to treat moderate to severe Crohn’s disease that hasn’t responded to other treatments, such as tumor necrosis factor (TNF) blockers.

It’s important to note that Tysabri should not be used with other immunosuppressants to treat Crohn’s disease. It also should not be used with TNF blockers.

Examples of immunosuppressants include azathioprine (Azasan), cyclosporine (Gengraf, Neoral), and methotrexate (Trexall, others)

Examples of TNF blockers include infliximab (Remicade), adalimumab (Humira), and golimumab (Simponi and Simponi Aria).

Using Tysabri with these medications could increase the risk of progressive multifocal leukoencephalopathy (PML) as a side effect. To learn more, see the “Boxed warning” section at the beginning of this article.

Crohn’s disease is a type of inflammatory bowel disease (IBD). It can affect any part of your digestive tract, but it most commonly affects the colon or small intestine.

Symptoms of Crohn’s disease can include:

  • diarrhea
  • belly cramps
  • bloody stool
  • fatigue (low energy)
  • fever
  • loss of appetite
  • weight loss
  • frequent bowel movements

Symptoms of Crohn’s disease can sometimes improve or worsen over time. If symptoms suddenly become worse, it’s known as a “flare-up” or “flare.”

Your doctor will recommend the dosage of Tysabri that’s right for you. Below are commonly used dosages, but the dosage you receive will be determined by your doctor.

Form and strength

Tysabri comes as a liquid solution that’s given as an intravenous (IV) infusion (an injection into a vein over a period of time).

Tysabri comes in one strength: 300 milligrams (mg) per vial.

Recommended dosage

To treat multiple sclerosis or Crohn’s disease, Tysabri infusions are usually given once every 4 weeks. You’ll receive Tysabri doses at your doctor’s office or another healthcare facility.

Questions about Tysabri’s dosage

Below are some common questions about Tysabri’s dosage.

  • What if I miss my Tysabri infusion appointment? If you miss an appointment to receive a Tysabri infusion, call your doctor’s office as soon as possible. They can help reschedule your appointment and adjust the timing of your future doses if needed.
  • Will I need to use Tysabri long term? If you and your doctor agree Tysabri is working well for you, you’ll likely use the drug long term.
  • How long does Tysabri take to work? Tysabri begins working as soon as you receive your first infusion. But it may take several weeks before you notice your symptoms ease. If you have questions about when you can expect to see results from Tysabri, talk with your doctor.

Both Tysabri and Ocrevus are prescribed to treat relapsing forms of multiple sclerosis (MS) in adults. Ocrevus may also be used to treat progressive (worsening) forms of MS in adults, whereas Tysabri may be prescribed to treat moderate to severe Crohn’s disease in adults.

Both Tysabri and Ocrevus are given by intravenous (IV) infusion (an injection into a vein over a period of time). Tysabri and Ocrevus cause similar side effects, but they can cause some different ones as well.

To learn more about how these drugs are alike and different, see this detailed comparison. Your doctor can also tell you whether Tysabri or Ocrevus may be an option for you.

It’s important to talk with your doctor about your overall health before you begin treatment with Tysabri. There are important considerations that affect whether the drug is safe for you. These include your medical history and any medications you may take.

Interactions

Taking a medication with certain vaccines, foods, and other things can affect how the medication works. These effects are called interactions.

Before starting treatment with Tysabri, be sure to tell your doctor about all medications you take, including prescription and over-the-counter types. Also, describe any vitamins, herbs, or supplements you use. Your doctor or pharmacist can tell you about any interactions these items may cause with Tysabri.

For information about drug-condition interactions, see the “Other warnings” section below.

Interactions with drugs or supplements

Tysabri can interact with several types of drugs. These drugs include:

  • Other immunosuppressants. Due to the risk of an interaction, doctors typically won’t prescribe Tysabri with these medications. Examples of immunosuppressants include:
    • azathioprine (Azasan)
    • cyclosporine (Gengraf, Neoral)
    • methotrexate (Trexall, others)
  • Tumor necrosis factor (TNF) blockers. Due to the risk of an interaction, doctors typically won’t prescribe Tysabri with TNF blockers. Examples of these drugs include:
  • Corticosteroids, such as prednisone (Rayos)

This list does not contain all types of drugs that may interact with Tysabri. Your doctor or pharmacist can tell you more about these interactions and any others that may occur with use of Tysabri.

Boxed warning: Risk of progressive multifocal leukoencephalopathy (PML)

Tysabri has a boxed warning for the risk of PML. A boxed warning is a serious warning from the Food and Drug Administration (FDA) about drug effects that may be dangerous.

PML is a rare but serious brain infection that’s been reported with Tysabri use. It often leads to disability, and it can even be fatal. There’s no known cure for PML.

To learn more, see the “Boxed warning” section at the beginning of this article.

Other warnings

Tysabri may not be right for you if you have certain medical conditions. These are known as drug-condition interactions. Other factors may also affect whether Tysabri is a good treatment option for you.

Talk with your doctor about your health history before you use Tysabri. Factors to consider include those in the list below.

  • HIV, AIDS, or another condition that weakens your immune system. Tysabri weakens your immune system, which raises your risk of infection. Tysabri may not be safe for you if you already have a weakened immune system. This can be due to certain conditions such as HIV, AIDS, lymphoma, or a past organ transplant. Your doctor can determine whether Tysabri is safe for you or if another treatment for your condition would be a better choice.
  • Infection. Tysabri weakens your immune system, which raises your risk of infection. If you already have an infection before starting Tysabri treatment, it may be harder to treat once you begin using Tysabri. Before starting treatment with Tysabri, tell your doctor if you have an infection. They’ll likely want to treat it before you begin treatment with Tysabri.
  • Allergic reaction. If you’ve had an allergic reaction to Tysabri or any of its ingredients, your doctor will likely not prescribe Tysabri. Ask them what other medications are better options for you.

Tysabri and alcohol

It should be safe to drink alcohol during your Tysabri treatment.

But alcohol and Tysabri can cause similar side effects, including headache, fatigue (low energy), and indigestion (upset stomach). Drinking alcohol during your Tysabri treatment may raise your risk of these side effects. It could also make these side effects more severe if you do experience them.

Further, drinking alcohol may worsen the symptoms of your condition. If you drink alcohol, talk with your doctor about how much is safe to drink during your Tysabri treatment.

Pregnancy and breastfeeding

It’s not known whether it’s safe to use Tysabri while pregnant. If you’re pregnant or planning to become pregnant, talk with your doctor before starting treatment with Tysabri.

It’s also not known if it’s safe to receive Tysabri infusions while breastfeeding. Studies have shown that the drug passes into breast milk. But it’s not known what effects this could have on a breastfed child or how it could affect breastmilk production.

If you’re breastfeeding or planning to breastfeed, talk with your doctor before starting treatment with Tysabri.

Your doctor will tell you about Tysabri’s administration (how it will be given to you). They’ll also explain how much you’ll be given and how often.

Receiving Tysabri

Tysabri comes as a liquid solution that’s given as an intravenous (IV) infusion (an injection into a vein over a period of time). You’ll receive Tysabri doses at your doctor’s office or another healthcare facility.

Questions about receiving Tysabri

Below are some common questions about Tysabri’s administration.

  • Can I eat before a Tysabri infusion? Food doesn’t affect Tysabri infusions. You can eat before your infusion appointments if you wish.
  • What’s the infusion time typically like with Tysabri? Tysabri infusions typically take about 1 hour. If you have questions about what to expect at your infusion appointments, talk with your doctor
Questions for your doctor

You may have questions about Tysabri and your treatment plan. It’s important to discuss all your concerns with your doctor.

Here are a few tips that might help guide your discussion:

  • Before your appointment, write down questions such as:
    • How will Tysabri affect my body, mood, or lifestyle?
  • Bring someone with you to your appointment if doing so will help you feel more comfortable.
  • If you don’t understand something related to your condition or treatment, ask your doctor to explain it to you.

Remember, your doctor and other healthcare professionals are available to help you. And they want you to get the best care possible. So, don’t be afraid to ask questions or offer feedback on your treatment.

Tysabri is used to treat multiple sclerosis (MS) or Crohn’s disease in certain adults. If you’re considering treatment with Tysabri, talk with your doctor. Ask questions to help you feel comfortable with your treatment options. Some example questions to get you started include:

  • Would an alternative to Tysabri, such as Tecfidera, be an option for me?
  • Do I have any health factors that could raise my risk of progressive multifocal leukoencephalopathy (PML) from Tysabri?
  • Can you tell me about clinics near me where I can get a Tysabri infusion?

In addition, you can sign up for Healthline’s multiple sclerosis or inflammatory bowel disease newsletter to learn more about these conditions.

You can also find support and advice from the Bezzy multiple sclerosis and inflammatory bowel disease communities.

Q:

I learned that Tysabri can cause depression. If I already have depression, is it safe for me to use Tysabri?

Anonymous

A:

Possibly. Your doctor will discuss the risks and benefits of Tysabri treatment with you. They’ll determine whether it’s safe for you to use the drug.

Depression was one of the more common side effects reported in Tysabri’s studies. It wasn’t reported whether people who already had depression experienced worsening symptoms after treatment with Tysabri.

In rare cases, people who experienced depression in studies of Tysabri had suicidal thoughts or actions.

If you have depression, talk with your doctor before starting Tysabri treatment. They can discuss the benefits and risks of Tysabri treatment with you. If you do use Tysabri, your doctor will likely monitor your mental health closely during treatment. If you have suicidal thoughts or actions during your Tysabri treatment, call 911 or your local emergency number.

The Healthline Pharmacist TeamAnswers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.

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.