Tysabri (natalizumab) is a medication primarily used to treat multiple sclerosis (MS) and Crohn’s disease by modifying the immune system to reduce inflammation and disease activity. While it can be highly effective, it also carries a range of potential side effects that patients and caregivers should be aware of.
**Common Side Effects**
Many people taking Tysabri experience mild to moderate side effects, especially during or shortly after the infusion. These can include:
– **Infusion-related reactions:** These are among the most frequent side effects and may involve headache, dizziness, nausea, fatigue, fever, chills, or rash. Some patients report itching or flushing during the infusion.
– **Respiratory symptoms:** Mild upper respiratory infections such as colds or sinus infections are common. Some patients may experience cough or sore throat.
– **Fatigue and weakness:** Feeling unusually tired or weak can occur, sometimes related to the underlying disease but also as a medication side effect.
– **Gastrointestinal discomfort:** Nausea or abdominal pain may be reported occasionally.
These side effects are generally manageable and often improve as the body adjusts to the medication.
**Serious and Less Common Side Effects**
Tysabri carries a risk of more serious adverse effects, some of which require immediate medical attention:
– **Progressive multifocal leukoencephalopathy (PML):** This is a rare but potentially fatal brain infection caused by the JC virus. It occurs because Tysabri suppresses immune surveillance in the brain, allowing the virus to reactivate. Symptoms of PML include new or worsening neurological problems such as weakness, vision changes, speech difficulties, or cognitive decline. Because of this risk, patients on Tysabri are closely monitored with regular MRI scans and blood tests.
– **Allergic reactions:** Severe allergic or hypersensitivity reactions can occur during or after infusion. Signs include swelling of the face or throat, difficulty breathing, chest pain, or severe rash. These require emergency treatment.
– **Liver injury:** Some patients may experience elevated liver enzymes or liver inflammation, which can cause symptoms like jaundice (yellowing of the skin or eyes), dark urine, or abdominal pain.
– **Infections:** By altering immune function, Tysabri can increase susceptibility to infections beyond PML, including respiratory infections and urinary tract infections.
– **Other neurological symptoms:** Rarely, patients may develop other neurological complications such as seizures or worsening MS symptoms.
**Less Frequent Side Effects**
– **Headache and dizziness:** These can occur independently of infusion reactions.
– **Joint or muscle pain:** Some patients report aches or stiffness.
– **Mood changes:** Anxiety or depression symptoms have been noted in some cases.
– **Skin reactions:** Rash or itching may develop, sometimes related to allergic responses.
**Managing Side Effects**
Because Tysabri is given by intravenous infusion, healthcare providers monitor patients closely during and after administration to manage any immediate reactions. Pre-medication with antihistamines or corticosteroids may be used to reduce infusion-related symptoms. Patients are advised to report any new neurological symptoms promptly to allow early detection of serious complications like PML.
Regular blood tests and MRI scans are part of ongoing monitoring to check for signs of infection or liver problems. If serious side effects occur, discontinuation of Tysabri may be necessary, and alternative treatments considered.
**Considerations**
The risk of serious side effects, especially PML, means that Tysabri is usually reserved for patients who have not responded well to other therapies or who have aggressive disease. The benefits of reducing MS relapses and slowing disease progression must be weighed carefully against these risks.
Patients should also inform their healthcare providers about any other medications or supplements they are taking, as drug interactions may influence side effects or effectiveness.
In summary, while Tysabri can cause a variety of side effects ranging from mild infusion reactions to seriou
