By skyforbes 
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.
† This wasn’t reported in studies of Gilenya but has been reported in people who took the drug once it became available. See the “What should be considered before taking Gilenya?” section below for details.
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.