MS pill

To understand how GILENYA affects the body, we need to start at the beginning.

Multiple sclerosis (MS) is an autoimmune disease that attacks the healthy tissues in the central nervous system (CNS). When MS attacks myelin—the covering that surrounds and protects the body's nerve fibers—nerve impulses are interrupted, causing MS symptoms.

See how GILENYA is thought to work

Research is still being done on which immune cells are mounting the attack, the factors that cause the attack, and the sites that appear to be attracted to the myelin to begin the destructive process. There are plenty of websites that provide a more thorough scientific description of this process (check out, for example), but here's a quick snapshot on how cells called lymphocytes affect the immune system.

The immune system contains a network of lymph nodes, which are tiny glands containing immune cells called lymphocytes. Lymphocytes are normally good guys, but sometimes they can go rogue. This can mean they go after your CNS and cause problems.

While it's not exactly clear how GILENYA works, it is thought to keep lymphocytes from attacking your CNS by lowering the number of lymphocytes circulating in your blood.

GILENYA may lead to a slow heart rate after you take your first dose—here's why

GILENYA works differently from other MS treatments. One difference—your heart rate is expected to slow down the first time you take GILENYA.

This slowdown is usually temporary. Not only that, in clinical trials, less than 1% of adults taking GILENYA experienced symptoms of slow heart rate. Whether you're part of this 1% or not, you will still be monitored during your first dose—so it's important for you to understand what's happening.

Why does GILENYA affect your heart?

By now, you know that MS happens when your lymphocytes, and other immune cells, mistakenly attack your central nervous system.

How can GILENYA help? GILENYA is thought to help by activating certain sensors on your lymph nodes, which keeps some white blood cells in your lymph nodes. That way, these white blood cells aren't released into your bloodstream, where they can attack your central nervous system.

GILENYA also activates certain sensors on your heart (similar to the ones on your lymph nodes), which cause your heart rate to slow down. Unlike the sensors on your lymph nodes, the effect on the sensors on your heart is temporary and only happens when you start GILENYA. This slowdown in heart rate is expected, and it's the reason you're monitored during your first dose.

If you're one of the few people who experiences symptoms of slow heart rate (such as dizziness, tiredness, feeling like your heart is beating slowly or skipping beats, or chest pain), the health care professional monitoring you can help you manage these symptoms.

Symptoms of slow heart rate usually happen within the first 6 hours of your first dose, and can happen up to 24 hours after your first dose. To help you start off safely and confidently, we'll make sure your heart rate is monitored by a health care professional for these first 6 hours when you take your first dose. If your ECG shows any heart problems or if your heart rate is still too low or continues to decrease, you will continue to be observed.

*This effect was only observed in animal models.


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Speak up and share your message. Tell multiple sclerosis (MS) how you really feel by posting your message on our "HEY MS" message board.

Make sure your voice is heard. We love that you want to say "Take This!" to relapsing MS, but there are still some words even we can't use—words that might not be appropriate. They're defined in the Community Guidelines below. But have no fear; we'll give you a heads up if you use any problematic words by highlighting them after you hit submit. So, go for it, and tell relapsing MS how you really feel!

  • Do not include medical advice or any non-approved use of GILENYA

  • No profane, indecent, or inappropriate language in your message or image, please (a no-no)

  • Avoid using your full name and/or e-mail address in your message, so this personal information remains private and protected

  • Do not include spam, such as links to or URLs for other websites or social networks in your message

  • Refrain from sharing any treatment and/or dosage information, as well as names of specific medicines (brand name or generic) and product manufacturers

  • Avoid mention of side effects from GILENYA. We take drug product safety seriously. You are encouraged to report negative side effects of prescription drugs to the FDA. Visit or call

Please note that in order to comply with our Community Guidelines as well as the FDA's Prescription Drug Advertising Guidelines, your statement may be subject to modification, while maintaining the spirit of your message. Your photo and statement may be used in other GILENYA marketing materials



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