Gilenya (fingolimod) is a brand-name prescription medication. It’s approved by the Food and Drug Administration (FDA) to treat certain forms of multiple sclerosis (MS) in adults and children ages 10 years and older.

Specifically, Gilenya is prescribed to treat relapsing-remitting MS and active secondary progressive MS. Gilenya is also prescribed to treat clinically isolated syndrome, which could be an early sign of MS.

Here are some fast facts about Gilenya:

  • Active ingredient: fingolimod
  • Drug class: sphingosine 1-phosphate receptor modulator (a type of disease-modifying therapy)
  • Drug form: oral capsule

Gilenya is meant to be a long-term treatment.

Like other drugs, Gilenya can cause side effects. Read on to learn about potential common, mild, and serious side effects. For a general overview of Gilenya, including details about its uses, see this article.

Gilenya can cause certain side effects, some of which are more common than others. These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

These are just a few of the more common side effects reported by people who took Gilenya in clinical trials:

* For more information about this side effect, see “Side effect specifics” below.

Mild side effects can occur with Gilenya. This list doesn’t include all possible mild side effects of the drug. For more information, you can refer to Gilenya’s prescribing information.

Mild side effects that have been reported with Gilenya include:

These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks side effects of the medication. If you develop a side effect while taking Gilenya and want to tell the FDA about it, visit MedWatch.

* For more information about this side effect, see “Side effect specifics” below.

Gilenya may cause serious side effects. The list below may not include all possible serious side effects of the drug. For more information, you can refer to Gilenya’s prescribing information.

If you develop serious side effects while taking Gilenya, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Serious side effects that have been reported and their symptoms include:

* For more information about this side effect, see “Side effect specifics” below.
† An allergic reaction is possible after taking Gilenya. However, it’s not clear whether this side effect occurred in clinical trials.

Gilenya is approved to treat certain forms of multiple sclerosis (MS) in children ages 10 years and older. (For information about the use of Gilenya in children, see this article.)

Most side effects of Gilenya in children are expected to be the same as those in adults. However, seizures may occur more commonly in children.

If you have questions about your child’s risk of side effects from Gilenya, talk with their doctor.

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

Eye-related side effects

Gilenya may cause ocular (eye-related) side effects. Blurred vision was a less common side effect in clinical trials of the drug.

Blurred vision can be a symptom of other rare but serious side effects of Gilenya, including macular edema and progressive multifocal leukoencephalopathy (PML). These conditions are described in more detail below.

Macular edema. Although rare, taking Gilenya can cause macular edema. This condition happens when fluid builds up in the retina (the layer of tissue lining the back of your eye).

In addition to blurred vision, macular edema can cause symptoms such as changes in the way you see colors and loss of vision. However, it’s possible for macular edema to occur without any symptoms.

In clinical trials of Gilenya, macular edema was more likely to occur in the first 3 or 4 months after treatment with the drug was started. However, this side effect can happen at any time during Gilenya treatment. You may have a higher risk of macular edema if you have diabetes or uveitis (swelling of the middle layer of tissues in the eye).

PML. Rarely, Gilenya can cause PML. This condition can lead to vision problems along with other symptoms such as confusion and changes in personality.

PML is a life threatening infection. It’s caused by a virus that attacks the central nervous system. PML wasn’t reported in clinical trials of Gilenya. However, PML has been reported as a side effect since the drug became available for public use.

What you can do

Because of Gilenya’s risk of eye-related side effects, your doctor will advise you to have an eye exam before you start taking the drug. They’ll likely suggest you have another eye exam 3 to 4 months later.

Be sure to tell your doctor if you have diabetes or uveitis before starting treatment with Gilenya. If so, they may recommend you continue to have eye exams periodically during treatment.

If you have eye-related side effects while taking Gilenya, talk with your doctor. They can check for more serious conditions, such as macular edema and PML. If you’re having severe eye problems, your doctor may advise you to stop taking Gilenya until your condition is treated or the side effect resolves.

Your doctor will watch for signs of PML while you’re taking Gilenya. If you have any symptoms of PML while taking the drug, call 911 or your local emergency number right away.

Hair loss

Hair loss is possible while taking Gilenya. This was a less common side effect in clinical trials of the drug.

What you can do

If you’re concerned about hair loss from Gilenya, talk with your doctor. They can suggest ways to manage this side effect, such as medications or other treatment options.

For example, your doctor may suggest you use an over-the-counter product to treat hair loss. An example is minoxidil (Rogaine). Or instead, they may suggest you limit the use of harsh hair products or styling tools.

Skin cancer

Gilenya may increase the risk of certain skin cancers. In rare cases, the use of Gilenya in clinical trials led to basal cell carcinoma (BCC). Melanoma has been reported as a side effect since the drug became available for public use.

Basal cell carcinoma. BCC affects basal cells, which are found on the outer layer of skin. This type of skin cancer typically causes bumps, sores, or discolored patches to form. These growths may appear crusty or scaly.

Melanoma. Melanoma affects cells that give color to your skin. Early stages of melanoma are difficult to detect. However, any changes to a sore on your skin that doesn’t heal or a sore that starts to bleed should be evaluated by your doctor.

What you can do

Below are a few tips to help lower your risk of skin cancer:

  • limit the time you spend in the sun
  • frequently apply broad-spectrum sunscreen with a sun protection factor (SPF) of 30 or more
  • wear clothing that protects your skin, such as a wide-brimmed hat or long sleeves
  • avoid the use of tanning beds

Watch for new or unusual skin changes while you’re taking Gilenya. It’s likely your doctor will check your skin for signs of cancer during treatment. Or they may suggest you see a dermatologist from time to time while you take the drug.

If you’re concerned about your risk of skin cancer with Gilenya, talk with your doctor.

Problems with digestion

Gilenya may cause problems with digestion. Nausea, diarrhea, and pain in the abdomen were common in clinical trials of the drug.

In severe cases, problems with digestion can lead to dehydration and loss of electrolytes.

What you can do

While taking Gilenya, it’s important to stay hydrated. You can do so by drinking fluids such as Pedialyte or Gatorade. These can also help prevent or correct any loss of electrolytes you may experience.

If you have problems with digestion while taking Gilenya, talk with your doctor. They may prescribe medications that can ease your symptoms.

Breathing problems

Gilenya may make it more difficult for you to breathe. Shortness of breath was a common side effect in clinical trials of the drug. Your doctor may monitor your breathing with pulmonary function tests while you are taking Gilenya. These tests check how well your lungs are working and will help your doctor measure if Gilenya is reducing how well your lungs work by too much.

What you can do

Before taking Gilenya, tell your doctor if you have breathing problems. The drug hasn’t been trialed in people who have these issues. Your doctor can advise you on whether it’s safe for you to take the drug.

Tell your doctor if you have new or worsening shortness of breath while taking Gilenya. They may order tests to check your breathing and lung function.

Allergic reaction

As with most drugs, Gilenya can cause an allergic reaction in some people. However, it’s not clear whether this side effect occurred in clinical trials.

Symptoms can be mild or serious and can include:

  • skin rash
  • itching
  • flushing
  • swelling under your skin, typically in your eyelids, lips, hands, or feet
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What you can do

For mild symptoms of an allergic reaction, call your doctor right away. They may recommend ways to ease your symptoms and determine whether you should keep taking Gilenya. However, if your symptoms are serious and you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Gilenya may cause several side effects. Here are some frequently asked questions about the drug’s side effects and their answers.

If I stop taking Gilenya, could I develop symptoms of withdrawal?

No, stopping Gilenya treatment isn’t likely to cause withdrawal symptoms. These are side effects that happen after you stop taking a drug your body has become dependent on.

It’s possible for your multiple sclerosis (MS) symptoms to worsen after stopping Gilenya treatment. This wasn’t reported in clinical trials of the drug. However, there have been reports of people having worsened MS symptoms after they stopped taking Gilenya. This typically happened within 12 to 24 weeks after treatment with the drug was stopped.

For this reason, it’s important to talk with your doctor before you stop taking Gilenya. They’ll likely switch you to a different treatment to lower your risk of worsened MS.

Are weight gain and weight loss side effects of Gilenya?

No, Gilenya isn’t likely to affect your weight. Weight gain and weight loss weren’t reported as side effects in clinical trials of the drug.

Keep in mind that weight changes are common with multiple sclerosis (the condition Gilenya is prescribed to treat). You may find that your weight fluctuates while taking Gilenya. However, these weight changes could be caused by MS rather than the drug itself.

If you have weight gain or weight loss while taking Gilenya, talk with your doctor. They can help determine the cause and suggest ways to manage your weight.

What are the long-term side effects of taking Gilenya?

Certain long-term side effects are possible with Gilenya.

For example, in rare cases, taking Gilenya may cause progressive multifocal leukoencephalopathy (PML). PML is a life threatening infection caused by a virus that attacks the central nervous system.

PML wasn’t reported in clinical trials of Gilenya. However, PML has been reported as a side effect since the drug became available for public use. In many cases, PML happened after people took Gilenya for longer than 2 years.

PML may cause symptoms such as vision problems, confusion, and changes in personality. Your doctor will watch for symptoms of PML while you’re taking Gilenya. If you notice any symptoms of PML, call 911 or your local emergency number right away.

Be sure to talk with your doctor about your health history before you take Gilenya. This drug may not be the right treatment option for you if you have certain medical conditions or other factors that affect your health. The conditions and factors to consider include:

Diabetes. Diabetes can increase your risk of macular edema. This rare but serious side effect happens when fluid builds up in the retina. Your doctor will likely recommend that you have eye exams periodically during treatment to watch for this side effect.

Heart problems. Before taking Gilenya, tell your doctor if you have any heart problems. Examples include heart failure, angina, and a recent heart attack. Doctors typically will not prescribe Gilenya if you have any of these conditions. This is because Gilenya can cause heart block as a side effect. And heart block may worsen your current heart problem. Your doctor can recommend a treatment option that’s safe for you.

Infections. Before taking Gilenya, tell your doctor about any infections you have. The drug can increase your risk of mild and serious infections, such as bronchitis or pneumonia. If you currently have an infection, your doctor will likely treat it before you start taking Gilenya.

Liver problems. If you have liver problems, your body may not be able to get rid of Gilenya as well as it should. This can raise the level of Gilenya in your body, which could increase your risk of side effects. Before starting treatment with Gilenya, tell your doctor about any liver problems you have.

Uveitis. Uveitis can increase your risk of macular edema as a side effect of Gilenya. Macular edema happens when fluid builds up in the retina. To watch for this side effect, your doctor will likely advise you to have eye exams periodically during treatment.

Allergic reaction. If you’ve had an allergic reaction to Gilenya or any of its ingredients, your doctor will likely not prescribe Gilenya. Ask your doctor what other medications may be better options for you.

Alcohol with Gilenya

There aren’t any known issues with drinking alcohol while taking Gilenya.

However, keep in mind that alcohol may worsen certain side effects of Gilenya, such as problems with digestion.* For this reason, you may want to limit the amount of alcohol you drink while taking the drug.

If you drink alcohol, talk with your doctor about the amount that’s safe for you to consume while taking Gilenya.

* For more information about this side effect, see “Side effect specifics” below.

Pregnancy and breastfeeding while taking Gilenya

Below is information about pregnancy and breastfeeding while taking Gilenya.

Pregnancy. Gilenya is not safe to take while pregnant. This is because animal studies have shown that Gilenya may cause harm to a fetus if the drug is taken during pregnancy. Animal studies don’t always predict what happens in humans. However, it’s still recommended to avoid taking Gilenya while you’re pregnant.

To confirm you aren’t pregnant, your doctor will order a pregnancy test for you before you start taking Gilenya.

If you’re able to become pregnant, you should use birth control while taking Gilenya. You should continue using birth control for at least 2 months after your last dose of Gilenya.

The manufacturer of Gilenya hasn’t provided recommendations for males* taking Gilenya. If you’re a male who’s sexually active with someone who can become pregnant, talk with your doctor about your birth control needs.

If you become pregnant while taking Gilenya, consider enrolling in a pregnancy registry. Pregnancy registries collect information about the safety of a drug when used during pregnancy. To learn more, talk with your doctor. You can also visit the Gilenya pregnancy registry website, or call 877-598-7237.

Breastfeeding. It’s not known for sure if Gilenya is safe to take while breastfeeding. If you’re breastfeeding or planning to do so while taking Gilenya, talk with your doctor. They can advise you on the best way to feed your child.

* Sex and gender exist on spectrums. Use of the term “male” in this article refers to sex assigned at birth.

Gilenya may cause mild or serious side effects. If you have bothersome side effects while taking Gilenya, talk with your doctor. They can suggest ways to ease your symptoms and answer any questions you may have about the drug’s side effects.

If you’d like to learn more about Gilenya, talk with your doctor or pharmacist. They can help answer any questions you have about side effects of taking the drug.

Besides talking with your doctor, you can do some research on your own. These articles might help:

  • More information about Gilenya. For details about other aspects of Gilenya, refer to this article.
  • A look at multiple sclerosis (MS). For details about MS, see our MS hub and list of MS articles. You can also refer to this article for a closer look at Gilenya for MS.

Disclaimer: Medical News Today 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.