If you have multiple sclerosis (MS), your doctor may prescribe Gilenya for you. It’s used in certain people with MS.

MS is a condition that affects communication between your brain and spinal cord, and the rest of your body.

Specifically, Gilenya can be used in adults and some children with relapsing forms of MS, including:

It’s also used to treat a condition called clinically isolated syndrome (CIS). This is often a first sign of MS, but doesn’t always lead to it.

For more information on the specific uses of Gilenya, see the “Is Gilenya used for MS?” section below.

Gilenya basics

The active drug ingredient in Gilenya is fingolimod. It’s only available as a brand-name medication. There are no generic forms of Gilenya.

Gilenya comes as capsules that you’ll take by mouth. You’ll likely only need to take Gilenya once daily.

Read on to learn more about Gilenya’s side effects, uses, and more.

Like most drugs, Gilenya may cause mild or serious side effects, or even some long-term side effects. The lists below describe some of the more common side effects. These lists don’t include all possible side effects.

Keep in mind that side effects of a drug can depend on:

  • your age
  • other health conditions you have
  • other medications you’re taking

Your doctor or pharmacist can tell you more about the potential side effects of Gilenya. They can also suggest ways to help reduce them.

Mild side effects

Here’s a list of some of the mild side effects that Gilenya can cause. To learn about other mild side effects, talk with your doctor or pharmacist, or read Gilenya’s medication guide.

Mild side effects of Gilenya that have been reported include:

Mild side effects of many drugs may go away within a few days or a couple of weeks. But if they become bothersome, talk with your doctor or pharmacist.

* For more information on this side effect, see the “Side effect focus” section below.

Serious side effects

Serious side effects from Gilenya can occur, but they aren’t common. If you have serious side effects from Gilenya, call your doctor right away. However, if you think you’re having a medical emergency, you should call 911 or your local emergency number.

Serious side effects of Gilenya that have been reported include:

* For more information on this side effect, see the “Side effect focus” section below.

Side effect focus

Learn more about some of the side effects Gilenya may cause.

Diarrhea

You may experience diarrhea while you take Gilenya. Diarrhea is one of the more common side effects of the drug.

Diarrhea from Gilenya is usually temporary or manageable. In studies, no one had to stop taking the drug due to diarrhea.

What might help

The following tips may help to manage diarrhea:

  • Stay hydrated. Dehydration (low fluid level in your body) from diarrhea can become serious, especially in children and older adults. Drink plenty of fluids when you have diarrhea, such as water or sports drinks with electrolytes.
  • Eat bland foods. Eating certain easy-to-digest foods can help. Consider following the BRAT diet, which consists of bananas, rice, applesauce, and toast. This diet may help ease short-term diarrhea.

If you have severe or bothersome diarrhea while you’re taking Gilenya, talk with your doctor. They may be able to suggest ways or medications to decrease this side effect.

Eye-related side effects

It’s possible, but rare, that Gilenya may cause eye-related side effects.

Specifically, Gilenya can cause macular edema, which is a fluid buildup in part of your eye called the retina. People who have this side effect usually have symptoms within the first 3 to 4 months after starting Gilenya treatment.

Some people may not have any symptoms of macular edema. But other people may experience symptoms such as:

What might help

Before you start taking Gilenya, your doctor will recommend an eye exam. Then they’ll recommend another eye exam 3 to 4 months after you’ve started treatment. These exams are done to compare your vision before and after starting Gilenya.

If you have diabetes or a history of uveitis (swelling in your eye), be sure to tell your doctor. If you have these conditions, there is a higher risk of developing macular edema while taking Gilenya. Your doctor may suggest a different treatment option for you.

If you have any symptoms of macular edema at any time while taking Gilenya, tell your doctor right away.

If your macular edema is severe, your doctor may recommend treating it. They may also recommend that you stop taking Gilenya. In studies, most cases of macular edema either improved or went away completely after this medication was stopped.

Progressive multifocal leukoencephalopathy (PML)

Progressive multifocal leukoencephalopathy (PML) is a very rare but serious infection that’s been reported with Gilenya use. Although PML didn’t occur in studies, there have been reports of this side effect happening. In these reports, most cases of PML occurred in people with a weakened immune system. And they usually happened in people taking Gilenya for longer than 2 years.

PML is an infection that affects the brain and can cause disability or even death.

Although it’s very rare, you should be aware of the symptoms of PML and report them to your doctor immediately. Symptoms may get worse over days or weeks and may include:

What might help

Throughout your treatment with Gilenya, your doctor will monitor you for symptoms of PML. If you develop symptoms, see a doctor right away. Your doctor will likely recommend that you stop taking Gilenya and they’ll treat your PML.

Allergic reaction

Allergic reaction has been reported with Gilenya use, but it’s not known how often it occurs.

Symptoms of a mild allergic reaction can include:

  • itchiness
  • skin rash
  • flushing (temporary warmth, redness, or deepening of skin color)

A more severe allergic reaction is rare but possible. Symptoms of a severe allergic reaction can include:

  • urticaria (hives)
  • angioedema (swelling under your skin), typically in your eyelids, lips, hands, or feet
  • swelling of your tongue, mouth, or throat, which can cause trouble breathing

Call your doctor right away if you have an allergic reaction to Gilenya. But if you think you’re having a medical emergency, call 911 or your local emergency number.

If you have multiple sclerosis (MS), your doctor may recommend Gilenya.

It’s used to treat certain types of MS and a condition called clinically isolated syndrome (CIS). Gilenya is used in adults and children ages 10 years and older for:

  • CIS. This is often the first stage of MS. But CIS doesn’t always lead to MS.
  • Relapsing-remitting multiple sclerosis (RRMS). With RRMS, your MS symptoms relapse (get worse), then remit (improve), in a cycle.
  • Active secondary-progressive multiple sclerosis (SPMS). With SPMS, your MS symptoms continue to get worse.

MS affects the covering of your nerves that connect your brain and spinal cord to the rest of your body. With MS, your immune system attacks this covering. This decreases your brain’s ability to communicate with the rest of your body.

With MS you may have:

It’s not known exactly how Gilenya works to treat MS. It’s possible that Gilenya treats MS by decreasing the amount of white blood cells in your brain and spinal cord. (Your white blood cells make up part of your immune system.)

Below are answers to some commonly asked questions about Gilenya.

Is Gilenya used to treat breast cancer?

No, Gilenya isn’t approved to treat breast cancer. It’s only approved to treat multiple sclerosis (MS) in certain people.

Taking Gilenya may increase your risk for certain types of cancer, including skin cancer and lymphoma.

A study is underway to see if Gilenya could be used for nerve pain from chemotherapy that’s used to treat breast cancer. In this study, Gilenya is being used to help with the nerve pain, not to treat the breast cancer itself.

If you have breast cancer, talk with your doctor about the best treatment plan for you.

Will I have weight loss or weight gain while I’m taking Gilenya?

Taking Gilenya should not affect your weight. Weight loss and weight gain weren’t reported as side effects in studies of the drug.

Still, changes in weight are common in people with MS, which Gilenya is used to treat. Symptoms of the disease, such as depression, fatigue (lack of energy), or trouble walking may result in weight gain. And an MS flare-up that is being treated with steroids may also result in weight gain. (Steroids can cause you to gain weight.)

But some people with MS may lose weight from the disease. This can be due to decreased muscle activity, which causes muscle loss. In others, weight loss can be due to depression with MS.

If you gain or lose weight while taking Gilenya, talk with your doctor. They’ll be able to help figure out what’s causing your weight to change and how best to manage it.

What’s the difference between Gilenya and Ocrevus?

Both Gilenya and Ocrevus are medications used to treat the following relapsing forms of MS:

Both drugs are also used to treat clinically isolated syndrome (CIS). This is often the first stage of MS, but doesn’t always lead to MS.

Ocrevus is also approved to treat a form of MS called primary progressive MS (PPMS).

Another big difference between the two medications is the way you take them. Gilenya is a capsule that you’ll take by mouth once daily. Ocrevus is a liquid solution that’s injected into a vein in your arm. You only need to get one dose of Ocrevus twice each year.

These medications have different active drugs in them. So they may cause you to have different side effects.

If you have more questions about which treatment option is best for you, talk with your doctor or pharmacist. They’ll be able to help you decide which medication may be the best option.

* To learn more about CIS, RRMS, and SPMS, see the “Is Gilenya used for MS?” section above.

How does Gilenya work?

Gilenya’s mechanism of action (how it works) isn’t known.

It’s thought that Gilenya works by reducing the number of white blood cells in your brain and spinal cord. Your white blood cells make up part of your immune system. And in people with MS, the immune system attacks the covering of brain and spinal cord nerves.

If you have more questions about how Gilenya may work to treat MS, talk with your doctor or pharmacist.

Will stopping Gilenya lead to withdrawal symptoms?

No, stopping Gilenya won’t cause withdrawal symptoms. But stopping the medication may cause your MS symptoms to come back.

Stopping Gilenya may also lead to severe worsening of MS in some people. This may occur within 12 weeks of stopping the drug, but it can happen later. Many people whose MS got worse after stopping Gilenya did not have the same level of ability as before or during treatment.

If you need to stop taking Gilenya, be sure to talk with your doctor first. And tell them if your MS symptoms get worse after you stop Gilenya. Your doctor will suggest ways to treat the symptoms.

Is it safe to suddenly stop taking Gilenya?

Unless your doctor recommends it, you should not suddenly stop taking Gilenya.

Stopping Gilenya can cause MS symptoms to come back. And they may become worse than they were before Gilenya treatment. It’s also possible that stopping Gilenya may lead to severe worsening of MS. Many people whose MS got worse after stopping Gilenya did not have the same level of ability as before or during treatment.

If you think you need to stop taking this drug, talk with your doctor first. They may switch you to a different medication to reduce the risk of your MS symptoms getting worse.

Your doctor will explain how you should take Gilenya. They’ll also explain how much to take and how often. Be sure to follow your doctor’s instructions. Below are commonly used dosages, but always take the dosage your doctor prescribes.

Taking Gilenya

Gilenya comes as a capsule that you’ll take by mouth, with water.

You should take a dose each day, without missing a dose. Gilenya should not be taken every other day.

Dosage

Usually, Gilenya only needs to be taken once daily. Your dose will depend on your age and weight.

When you take your first dose of Gilenya, your doctor will monitor you, either in their office or at a hospital. This is because Gilenya may cause your heart rate to decrease to unsafe levels. And if that happens, you’ll be in your doctor’s office or a hospital, where you can be treated right away. Usually, people who have changes in heart rate or blood pressure experience these changes within 6 hours of their first dose.

Questions about taking Gilenya

Below are some commonly asked questions about Gilenya.

  • What if I miss a dose of Gilenya? You should try not to miss a dose of Gilenya. If you miss one or more doses, your doctor may check your heart after you take a dose, the same as when you first start treatment. (This means you may have to go to your doctor’s office or a hospital for another 6 hours when you take your next dose.) If you miss a dose, call your doctor right away. They’ll be able to tell you what to do about your next dose.
  • Will I need to use Gilenya long term? If Gilenya works for you, your doctor may recommend that you take it long term. But discuss your specific treatment plan with them before starting Gilenya.
  • Can Gilenya be chewed, crushed, or split? Gilenya is a capsule that’s swallowed with water. The manufacturers of Gilenya don’t give any recommendations about chewing, crushing, or splitting Gilenya capsules. If you’re having trouble swallowing the capsules, talk with your doctor or pharmacist. They may be able to recommend ways to make your medication easier to swallow.
  • Should I take Gilenya with food? You can take your dose of Gilenya with or without food.
  • How long does Gilenya take to work? Gilenya starts to work as soon as you take your first dose. But it can take weeks or even months before you notice your symptoms getting better. Talk with your doctor about when you can expect your symptoms to start improving.
Questions for your doctor

You may have questions about Gilenya and your treatment plan. It’s important to discuss all your concerns with your doctor.

Here are a few tips that might help guide your discussion:

  • Before your appointment, write down questions such as:
    • How will Gilenya affect my body, mood, or lifestyle?
  • Bring someone with you to your appointment if doing so will help you feel more comfortable.
  • If you don’t understand something related to your condition or treatment, ask your doctor to explain it to you.

Remember, your doctor and other healthcare professionals are available to help you. And they want you to get the best care possible. So don’t be afraid to ask questions or offer feedback on your treatment.

Before you start taking Gilenya, be sure to tell your doctor about your overall health. This includes any medical conditions you have and any medications you’re currently taking.

In some cases, other medical conditions or drugs may interact with Gilenya or cause serious side effects.

These and other considerations are described below.

Interactions

Taking medications, vaccines, foods, and other things with a certain drug can affect how the drug works. These effects are called interactions.

Before taking Gilenya, be sure to tell your doctor about all medications you take, including prescription and over-the-counter types. Also describe any vitamins, herbs, or supplements you use. Your doctor or pharmacist can tell you about any interactions these items may cause with Gilenya.

Interactions with drugs or supplements

Gilenya can interact with several types of drugs. These drugs include:

This list does not contain all types of drugs that may interact with Gilenya. Your doctor or pharmacist can tell you more about these interactions and any others that may occur with use of Gilenya.

Other interactions

Gilenya can interact with certain vaccines.

You should not get live vaccines while you’re taking Gilenya. And you should not have them for at least 2 months after stopping Gilenya.

Live vaccines contain weakened forms of live germs. Gilenya weakens the activity of your immune system. So getting a live vaccine while taking the drug may cause the infection the vaccine is meant to protect you from.

Non-live vaccines may not work as well if you get them while you’re taking Gilenya. These vaccines don’t contain live forms of the germs they’re meant to protect you from.

Before you start treatment with Gilenya, your doctor will discuss your vaccine needs with you. If you need any vaccines, they may recommend getting them before you start taking Gilenya.

Warnings

Gilenya may not be right for you if you have certain medical conditions or other factors that affect your health. Talk with your doctor about your health history before you take Gilenya. Factors to consider include those in the list below.

  • Current infections. Gilenya weakens the activity of your immune system, decreasing your body’s ability to fight infections. If you have any infections, your doctor will treat them before you start Gilenya.
  • Allergic reaction. If you’ve had an allergic reaction to Gilenya or any of its ingredients, you should not take Gilenya. Ask your doctor what other medications are better options for you.
  • Diabetes. If you have diabetes, you may have an increased risk for an eye problem called macular edema. Your doctor may monitor you more often than usual during treatment with Gilenya to watch for macular edema.
  • Uveitis (swelling in your eye). If you’ve had uveitis, you may have an increased risk for an eye problem called macular edema. Your doctor may monitor you more often than usual during treatment with Gilenya to watch for macular edema.
  • Liver problems. Gilenya may cause liver problems or changes in liver function tests. Talk with your doctor if you’ve ever had liver problems, as Gilenya may make them worse.
  • Heart problems. Gilenya can cause a slow heart rate or a condition called heart block. If you have a heart problem, Gilenya can make it worse. Examples of these heart problems include recent heart attack, unstable angina, stroke, heart failure, repeated fainting episodes, or a heart rhythm problem. If you have certain heart conditions, your doctor may recommend a different medication instead of Gilenya. In some cases, you may still be able to take Gilenya, but you’ll need monitored by your doctor more often than usual during treatment.
  • Recent vaccination. If you’ve recently gotten a vaccine, or you’re planning to get one, tell your doctor before you start Gilenya. They may suggest you wait before you begin Gilenya treatment.
  • Breathing problems, such as asthma. It’s possible that Gilenya may decrease the amount of air that you can breathe out of your lungs. If you have breathing problems, this decrease may make it more difficult for you to breathe. Your doctor may check your breathing during treatment with Gilenya.
  • High blood pressure. Gilenya can cause increased blood pressure. Tell your doctor if you already have high blood pressure, as Gilenya can make it worse.
  • Skin cancer. Gilenya may increase your risk for skin cancer. If you’ve ever had or you have skin cancer, tell your doctor before starting Gilenya.

Gilenya and alcohol

There are no known interactions between Gilenya and alcohol. But drinking alcohol while taking Gilenya may increase your risk for side effects from the drug.

For example, Gilenya can cause liver problems, and so can alcohol. So, drinking alcohol if you’re taking Gilenya may increase your risk for liver problems.

Talk with your doctor about whether there is a safe amount of alcohol for you to drink while you’re taking Gilenya.

Pregnancy and breastfeeding

Before starting Gilenya, tell your doctor if you’re breastfeeding, pregnant, or planning to become pregnant.

Gilenya and pregnancy

You should not take Gilenya if you’re pregnant. Your doctor will recommend using birth control while taking Gilenya and for at least 2 months after you stop taking the drug. This is how long it can stay in your system.

There is a registry for people who take Gilenya during pregnancy. A pregnancy registry is a collection of information given by people who took Gilenya while pregnant. This information is used to help doctors and patients decide if the drug may be harmful to a developing fetus.

You or your doctor can sign you up for the Gilenya pregnancy registry at www.gilenyapregnancyregistry.com.

Gilenya and breastfeeding

It’s not known if Gilenya is present in breast milk, or if it’s safe to breastfeed a child while taking Gilenya.

If you’re taking Gilenya, talk with your doctor about the best way to feed your child.

Both Gilenya and Tecfidera are used to treat certain forms of relapsing multiple sclerosis (MS).

These medications both come as capsules that you’ll take by mouth. But Gilenya capsules only need to be taken once daily, while Tecfidera needs to be taken twice per day.

These medications have different active drugs in them, so they may cause different side effects.

If you’d like to learn more about how Gilenya and Tecfidera are similar and different, see this article. And be sure to discuss with your doctor which drug is right for you.

Costs of prescription drugs can vary depending on many factors. These factors include what your insurance plan covers and which pharmacy you use. To find current prices for Gilenya capsules in your area, visit GoodRx.com.

If you have questions about how to pay for your prescription, talk with your doctor or pharmacist. You can also visit the Gilenya manufacturer’s website to see if they have support options.

Do not take more Gilenya than your doctor prescribes. Using more than this can lead to serious side effects.

Symptoms of overdose

Symptoms of an overdose can include:

What to do in case you take too much Gilenya

Call your doctor if you think you’ve taken too much Gilenya. You can also call 800-222-1222 to reach the American Association of Poison Control Centers, or use its online resource. However, if you have severe symptoms, immediately call 911 (or your local emergency number) or go to the nearest emergency room.

If you have multiple sclerosis (MS), your doctor may prescribe Gilenya for you. It’s used in certain people with MS.

If you have questions about taking Gilenya, talk with your doctor. They’ll be able to discuss any concerns you may have about this medication. They can also help you decide if Gilenya is a good treatment option for you.

Some examples of questions that you may wish to ask your doctor include:

  • How can I prevent or treat the side effects of Gilenya?
  • Can I get the COVID-19 vaccine while I’m taking Gilenya?
  • What other treatment options do I have if I can’t afford Gilenya?
  • Is Gilenya a safe treatment option for my MS, even though I have other medical conditions?

For more information about MS and its treatment options, see this article. To learn about natural options for treating MS, read Going Herbal: Vitamins and Supplements for Multiple Sclerosis.

If you’d like to stay up to date on information about MS, including its treatment options, sign up for Healthline’s MS newsletter.

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.