Key takeaways:
Tysabri (natalizumab) is a biologic medication that’s given as an intravenous infusion. It’s used to treat Crohn’s disease and relapsing forms of multiple sclerosis.
The most common Tysabri side effects include headache, fatigue, and joint pain. Infections, nausea, and depression are also possible. Certain side effects may be from the condition being treated.
Your care team will review the potential Tysabri risks with you. This includes an increased risk of a serious brain infection called progressive multifocal leukoencephalopathy.
Save on related medications
Tysabri (natalizumab) is a biologic medication that’s given as an intravenous (IV) infusion. It’s used to treat Crohn’s disease (CD) and relapsing forms of multiple sclerosis (MS). If you’ve been prescribed Tysabri, you’ll need to enroll in the TOUCH Prescribing Program to manage potential risks of treatment.
Common Tysabri side effects include headache, fatigue, and joint pain. And since Tysabri can suppress your immune system, serious infections can develop. You’ll also need to be monitored for an hour after your first 12 infusions in case you have a reaction.
While serious Tysabri side effects are possible, keep in mind that not everyone experiences them. Your care team will help you understand the potential benefits and risks of treatment for your specific situation.
Tysabri side effects at a glance
Some Tysabri side effects can be managed at home. But others may be more serious and require medical assistance.
Common Tysabri side effects include:
Headache
Fatigue
Joint pain
Nausea
Chest discomfort
Urinary tract infection (UTI)
Urinary changes
Lower or upper respiratory tract infection
Swelling in the extremities
Back pain
Menstrual cycle changes
Tooth infection
Depression
Examples of less common but serious Tysabri side effects include:
Herpes infections
Blood clotting problems
Liver damage
Serious infections
Allergic reactions
Progressive multifocal leukoencephalopathy (PML)
Below is an in-depth look at 10 of these Tysabri side effects. Some are more common depending on whether you have MS or CD.
1. Headache
Headache is the most commonly reported Tysabri side effect. If you develop a headache within 2 hours of starting your Tysabri infusion, this is considered an infusion-related reaction. Your care team can provide instructions on how to manage it.
If you need short-term relief, your care team may recommend an over-the-counter (OTC) pain reliever that’s safe for you to take. You can try home remedies to help you feel better, too. But you should let your team know if your headache gets worse or doesn’t go away.
Keep in mind that certain pain relievers, such as nonsteroidal anti-inflammatory drugs (NSAIDs), may worsen CD flares. It’s usually best to avoid these if you have CD.
Infusions for multiple sclerosis: Tysabri (natalizumab) is one of several injections or infusions for multiple sclerosis (MS). Here’s what you should know about your options.
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Monoclonal antibodies explained: Monoclonal antibodies, such as Tysabri, can be effective treatment options for MS. Explore how they work, potential benefits, and side effects to be aware of.
2. Fatigue
Fatigue is another common Tysabri side effect. But keep in mind that MS and CD can cause fatigue, too, as well as other medications and certain health conditions. And a small study found that Tysabri may actually help MS-related fatigue.
Take note if you feel more tired after starting Tysabri infusions. Getting adequate rest, eating a well-balanced diet, and exercising regularly can help improve energy levels.
But if fatigue starts to affect your daily routine, discuss it with your healthcare team. They can help you determine whether the cause is Tysabri or something else.
3. Joint pain
Some people experience joint pain during treatment with Tysabri. Similar to fatigue, this may be from MS or CD. For example, having CD can increase the likelihood of developing certain types of arthritis.
Tell your healthcare team if you notice pain or swelling in your joints while receiving Tysabri. They can determine the cause and best next steps. If needed, they may recommend certain medications to manage your symptoms.
As mentioned above, NSAIDs should usually be avoided if you have CD, so don’t take them without speaking to your healthcare team first.
4. Nausea
Some people receiving Tysabri for CD reported nausea as a side effect during clinical trials. However, nausea is a common CD symptom, and people who didn’t receive Tysabri also reported nausea at a relatively similar rate.
Your care team will likely monitor you for symptoms such as nausea during and after your infusion of Tysabri. If you develop sudden nausea after leaving your appointment, or if your nausea is persistent or starts getting worse, contact your healthcare team right away.
It’s important to note that nausea can also be a symptom of more serious Tysabri reactions, such as hypersensitivity reactions (including anaphylaxis) or liver damage. More on these later.
5. Infections
Tysabri works by suppressing your immune system. While this can help reduce MS and CD flares, it can also leave you more vulnerable to infections. Examples include pneumonia and urinary tract infections (UTIs).
Tysabri can also increase the risk of encephalitis and meningitis from herpes viruses, which can be life-threatening. Seek emergency medical care if you develop an unusual fever, severe headaches, or a stiff, painful neck.
Another possible herpes infection is acute retinal necrosis (ARN). Symptoms include changes in vision, eye pain, and eye redness. If you notice any unusual changes in your vision or eyes, talk to your healthcare team right away. In serious cases, ARN can lead to blindness.
Since Tysabri can interfere with your ability to fight off infections, it’s best to contact your healthcare team if you get sick. They can help determine the cause and how it should be treated.
6. Depression
Depression is another possible Tysabri side effect. During clinical trials, it was reported more frequently in people receiving Tysabri for MS. But it’s important to keep in mind that depression can be common in people with MS, affecting about 1 in 3 people living with the condition.
If you notice any changes in your mood or thinking, talk to your healthcare team. There are many treatment options for depression. Community resources can also help connect you with others living with MS for support.
If you or someone you know is thinking about suicide, help is available. Call the National Suicide Prevention Lifeline at 988. Or just text the word “HOME” to 741741 to reach the Crisis Text Line.
7. Blood clotting problems
In rare cases, Tysabri can cause blood clotting problems, such as immune thrombocytopenic purpura (ITP). This condition causes low levels of platelets (cells that help blood clot) in your blood, resulting in abnormal bleeding and easy bruising. ITP can become serious if it’s left untreated. Let your healthcare team know if you notice these symptoms.
8. Liver damage
During clinical trials, some people had elevated liver enzymes while receiving Tysabri, which can indicate liver damage or inflammation. There have also been a few cases of liver damage resulting in jaundice (yellowing of the skin and eyes).
Your healthcare team will likely monitor your liver health periodically during treatment. If your liver enzymes are significantly elevated, or if you develop liver damage symptoms, they may have you stop taking Tysabri.
Let your healthcare team know right away if you develop symptoms such as:
Extreme fatigue
Loss of appetite
Right upper abdominal pain
Dark-colored urine
Jaundice
9. Hypersensitivity reactions
Hypersensitivity reactions have happened after receiving Tysabri. This is one of the reasons you’ll be monitored for an hour after your infusion. While rare, severe hypersensitivity reactions, such as anaphylaxis, can occur with Tysabri. Anaphylaxis can progress quickly and become life-threatening.
Symptoms of a hypersensitivity reaction include:
Itching
Dizziness
Fever
Nausea
Flushing
Chest pain
Shortness of breath
If you develop symptoms of a hypersensitivity reaction during or after your infusion, your care team will be ready and able to provide treatment. Seek emergency care if you develop these symptoms after leaving your appointment.
Good to know: It’s important to stay on track with your Tysabri infusions. If you skip your infusion or delay it for an extended period of time, you may be more likely to have a hypersensitivity reaction at your next appointment. It’s also possible that Tysabri may not work as well for you.
10. Progressive multifocal leukoencephalopathy
One of the most serious Tysabri side effects is progressive multifocal leukoencephalopathy (PML). PML is a serious, life-threatening viral brain infection.
By enrolling in the TOUCH prescribing program, you’ll be educated on the risk of PML before and during your Tysabri treatments. The risk is low, estimated to affect about 4 out of 1,000 people who receive Tysabri.
You’re more likely to develop PML if you’ve had a John Cunningham virus (JCV) infection. Your healthcare team will test you for JCV antibodies before and periodically during treatment.
Additional risk factors for PML include:
Receiving Tysabri for over 2 years
Prior treatment with a medication that weakens your immune system
Let your healthcare team know right away if you develop symptoms such as one-sided body weakness and changes in vision, thinking, or memory.
When should you contact your healthcare team about Tysabri side effects?
You’ll be monitored for certain Tysabri side effects, such as hypersensitivity reactions, during and after your infusion. But if any side effects develop or persist afterward, or if you develop signs of an infection, contact your healthcare team.
Serious Tysabri side effects, including ITP, liver damage, and PML aren’t common. But you should reach out to your healthcare team right away if you notice symptoms such as jaundice, unusual bleeding or bruising, or changes in vision or memory.
Frequently asked questions
Common side effects of Tysabri, such as headaches and nausea, tend to be mild and short-lived. They’ll typically resolve within a few days to weeks after your infusion. But you should tell your healthcare team if any get worse or become severe.
Some Tysabri side effects may last longer or come and go between infusions. And more serious side effects, such as infections or liver issues, may develop more slowly and require monitoring over time.
Tysabri and Ocrevus (ocrelizumab) are both effective treatments for relapsing forms of MS. The best option for you depends on your specific type of MS, risk factors, and how well you respond to treatment.
Tysabri: Typically, people who haven’t responded to other treatments use Tysabri. It’s known for its rapid effects. But it carries a higher risk of PML, especially for people who test positive for the JC virus.
Ocrevus: This medication is approved for both relapsing and primary progressive MS. It’s often preferred for when the risk of PML or certain infections needs to be minimized.
Your healthcare team can help compare benefits, risks, and monitoring needs based on your situation.
Yes, hives can occur as an infusion-related reaction to Tysabri. These reactions typically happen during or shortly after an infusion, and may be accompanied by itching, rash, or swelling. But if these symptoms develop after your appointment, report them to your infusion center or healthcare team right away.
In rare cases, hives could be a sign of a more serious allergic reaction. Seek emergency medical care if they’re accompanied by trouble breathing, dizziness, or swelling of the face or throat.
Common side effects of Tysabri, such as headaches and nausea, tend to be mild and short-lived. They’ll typically resolve within a few days to weeks after your infusion. But you should tell your healthcare team if any get worse or become severe.
Some Tysabri side effects may last longer or come and go between infusions. And more serious side effects, such as infections or liver issues, may develop more slowly and require monitoring over time.
Tysabri and Ocrevus (ocrelizumab) are both effective treatments for relapsing forms of MS. The best option for you depends on your specific type of MS, risk factors, and how well you respond to treatment.
Tysabri: Typically, people who haven’t responded to other treatments use Tysabri. It’s known for its rapid effects. But it carries a higher risk of PML, especially for people who test positive for the JC virus.
Ocrevus: This medication is approved for both relapsing and primary progressive MS. It’s often preferred for when the risk of PML or certain infections needs to be minimized.
Your healthcare team can help compare benefits, risks, and monitoring needs based on your situation.
Yes, hives can occur as an infusion-related reaction to Tysabri. These reactions typically happen during or shortly after an infusion, and may be accompanied by itching, rash, or swelling. But if these symptoms develop after your appointment, report them to your infusion center or healthcare team right away.
In rare cases, hives could be a sign of a more serious allergic reaction. Seek emergency medical care if they’re accompanied by trouble breathing, dizziness, or swelling of the face or throat.
The bottom line
Common Tysabri (natalizumab) side effects include headaches, fatigue, and joint pain. Infections, nausea, and depression are also possible. In some cases, certain side effects may be from the health condition being treated instead of the medication.
Serious Tysabri side effects aren’t common. But they can include blood clotting problems, liver damage, and progressive multifocal leukoencephalopathy. The TOUCH prescribing program is designed to keep you informed about your personal risks when receiving Tysabri.
Speak to your prescriber or infusion team if you have questions about your Tysabri infusions.
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References
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LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. (2020). Natalizumab. National Institute of Diabetes and Digestive and Kidney Diseases.
National Heart, Lung, and Blood Institute. (2025). Immune thrombocytopenia (ITP).
National Multiple Sclerosis Society. (n.d.). Pain and itching.
O’Leary, S., et al. (2023). Practical clinical guidelines for natalizumab treatment in patients with relapsing multiple sclerosis. Journal of Infusion Nursing.
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Svenningsson, A., et al. (2013). Natalizumab treatment reduces fatigue in multiple sclerosis. Results from the TYNERGY trial; A study in the real life setting. PLoS One.
Vivekanandan, G., et al. (2021). Risk of progressive multifocal leukoencephalopathy in multiple sclerosis patient treated with natalizumab: A systematic review. Cureus.
