What is Tysabri (Natalizumab)?
Tysabri, with the chemical name natalizumab, is a monoclonal antibody medication used to treat relapsing forms of multiple sclerosis (MS) and Crohn's disease (CD) in adults [1.9.1, 1.9.4]. It is typically prescribed when other treatments have not been effective [1.9.2]. Tysabri is administered as an intravenous (IV) infusion every four weeks in a certified medical facility [1.2.5, 1.9.5]. It is classified as an immunosuppressant and works by targeting the activity of the immune system to reduce inflammation [1.9.5].
How Does Tysabri Work?
Tysabri's mechanism of action involves binding to a protein called alpha-4 integrin, which is found on the surface of immune cells (leukocytes) [1.3.2]. In conditions like MS, these activated immune cells cross the blood-brain barrier, entering the central nervous system and causing inflammation and damage to the myelin sheath that protects nerve fibers [1.3.3]. By blocking the alpha-4 integrin, Tysabri prevents these immune cells from migrating into the brain and spinal cord, thereby reducing inflammation and the frequency of relapses [1.3.2, 1.3.3].
The Link Between Tysabri and Headaches: Can Tysabri Cause Migraines?
Headache is the most frequently reported side effect associated with Tysabri treatment [1.6.3]. Clinical studies have shown that up to 38% of MS patients treated with Tysabri experience headaches, compared to 33% of those on a placebo [1.8.2]. While the term 'headache' is used broadly in clinical data, it's a known infusion-related reaction that can occur within two hours of the infusion [1.6.3, 1.4.1].
Although the official prescribing information primarily lists "headache," the severity and accompanying symptoms can sometimes align with a migraine diagnosis. A severe headache is also listed as a symptom of more serious potential side effects, such as herpes infections of the brain (encephalitis or meningitis) [1.4.2, 1.6.1]. Therefore, while Tysabri is directly linked to causing headaches, and these can be severe, it is crucial for patients to report the nature of their headaches—whether they have migraine-like features such as light sensitivity, nausea, or are debilitating—to their healthcare provider.
Understanding and Managing Tysabri-Related Headaches
Headaches associated with Tysabri can be part of an infusion reaction, which may also include symptoms like dizziness, fatigue, and nausea [1.4.1]. For many, these headaches are mild and may lessen over time as the body adjusts to the medication [1.8.5].
Management strategies include:
- Over-the-the-Counter (OTC) Pain Relievers: For mild headaches, a healthcare provider may recommend an OTC pain reliever. However, patients with Crohn's disease should be cautious, as some NSAIDs can worsen their condition [1.6.3].
- Pre-medication: In some cases, doctors may administer medications like antihistamines or corticosteroids before the infusion to reduce the risk or severity of infusion reactions.
- Monitoring: During and after the infusion (typically for at least one hour), healthcare professionals monitor patients for any adverse reactions, including severe headaches [1.5.1].
- Communication: It is vital to inform the medical team immediately if a headache develops during or after an infusion. If a headache is severe, persistent, or accompanied by other concerning symptoms like fever, confusion, or vision changes, it could indicate a more serious condition and requires immediate medical attention [1.5.3].
Tysabri Side Effects Comparison Table
When considering a disease-modifying therapy (DMT) for MS, it's helpful to compare the side effect profiles of different options. Below is a comparison of common side effects for Tysabri, Ocrevus (ocrelizumab), and Gilenya (fingolimod).
| Side Effect | Tysabri (Natalizumab) | Ocrevus (Ocrelizumab) | Gilenya (Fingolimod) |
|---|---|---|---|
| Administration | IV Infusion every 4 weeks [1.2.5] | IV Infusion every 6 months | Oral capsule, once daily |
| Headache | Very Common (up to 38%) [1.2.5] | Common (infusion-related) [1.7.1] | Common |
| Infusion Reaction | Common (24%) [1.6.5] | Very Common | Not applicable (oral medication) |
| Infection Risk | Increased risk, especially of PML, a rare brain infection [1.2.2]. | Increased risk of infections [1.7.1]. | Increased risk of infections. |
| Fatigue | Very Common (up to 27%) [1.2.5] | Common | Common |
| Liver Issues | Can cause liver damage [1.4.2]. | Can cause Hepatitis B reactivation. | Can cause elevated liver enzymes. |
| Cardiac Effects | Rare, can cause low blood pressure during infusion [1.4.2]. | Not a primary side effect. | Can cause a slow heart rate (bradycardia) after the first dose. |
Other Common and Serious Side Effects of Tysabri
Beyond headaches, Tysabri carries a risk of other side effects, ranging from common to severe.
Common Side Effects
Besides headache, other common side effects (affecting ≥10% of patients) include [1.8.2]:
- Fatigue
- Urinary tract infection (UTI)
- Joint pain (arthralgia)
- Depression
- Lung or respiratory tract infection
- Pain in arms or legs
- Rash
Serious Side Effects
Progressive Multifocal Leukoencephalopathy (PML): This is the most serious risk associated with Tysabri [1.2.2]. PML is a rare and often fatal viral infection of the brain caused by the John Cunningham (JC) virus in individuals with weakened immune systems [1.2.3]. Due to this risk, Tysabri is only available through a special restricted distribution program called the TOUCH® Prescribing Program [1.4.6]. Risk factors for PML include the presence of anti-JCV antibodies, prior use of immunosuppressants, and treatment duration longer than two years [1.2.2].
Other serious side effects can include [1.4.2, 1.5.4]:
- Serious Allergic Reactions: Including anaphylaxis, which can occur within two hours of the infusion.
- Liver Damage (Hepatotoxicity): Symptoms include jaundice, dark urine, and fatigue.
- Herpes Infections: Increased risk of encephalitis or meningitis caused by herpes viruses, which can be fatal.
- Low Platelet Counts: This can lead to easier bruising or bleeding.
Conclusion
To directly answer the question: yes, Tysabri can cause headaches, and it is the most common side effect reported by patients. While clinical data uses the general term "headache," these can be severe and may present as migraines. It is essential for patients experiencing severe or persistent headaches, especially those accompanied by other neurological symptoms, to communicate with their healthcare provider for proper diagnosis and management. The decision to use Tysabri requires a careful discussion of its benefits in controlling MS or Crohn's disease against its potential risks, including the significant concern of PML.
For more detailed safety information, you can visit the official TYSABRI® Patient Website.
