Tysabri works in a different way from other multiple sclerosis drugs. It keeps the white blood cells of the immune system from entering the brain and spinal cord, which doctors think plays an important role in the damaging effects of MS.
How Do I Take It?
You’ll go to your doctor’s office to get the drug through a vein. That will take about an hour every 4 weeks.
What Are the Side Effects?
The most common ones are:
It’s possible for some people to have an allergic reaction to Tysabri. Symptoms include anaphylaxis, hives, itching, breathing problems, chest pain, nausea, flushing, dizziness, and rash. You’ll need to stay at your doctor’s office for about an hour after you get the drug to make sure the reaction doesn’t happen.
After the FDA first approved Tysabri, the drug's manufacturer took it off the market due to reports of a rare but serious brain infection called PML (progressive multifocal leukoencephalopathy). The company introduced a program that requires everyone taking the medicine to register and to follow up every so often in order to find any possible cases of PML as soon as possible. With these safety programs in place, the drug went back on the market.
Your risk for PML goes up with the number of doses you take. It’s also higher for people who’ve taken drugs that turn down their immune systems before they use Tysabri or if you have a history history of infection with JC virus (John Cunningham virus). Because of this risk, doctors usually recommend Tysabri only for people who’ve tried other MS treatments that haven’t worked.
Besides PML and allergic reactions, other serious side effects include liver damage and serious infections.
Talk with your doctor about these side effects and whether Tysabri would be a good option for you. Together you can weigh the risks and benefits and decide if you should take the drug.