Gilenya Safety and Side Effects


The most common side effects or adverse effects reported in a large clinical trial of Gilenya included headache, influenza, diarrhea, back pain, increased liver enzymes (alanine transaminase or ALT, and aspartate aminotransferase or AST) which indicate impaired liver function, and cough. Common side effects that occurred with Gilenya are shown in the table below, including the percentage of Gilenya and placebo patients who were affected by each.

Adverse effects in study of Gilenya


Placebo (N=418)

Copaxone (N=425)

Headache 23% 25%
Vasodilation 5% 20%
Rash 11% 19%
Impaired liver function (increased AST/ALT) 5% 14%
Influenza viral infections 10% 13%
Diarrhea 7% 12%
Back pain 7% 12%
Cough 8% 10%
Herpes viral infections 8% 9%
Dyspnea 5% 8%
Depression 7% 8%
Bronchitis 4% 8%
Sinusitis 5% 7%
Dizziness 6% 7%
Hypertension 4% 6%
Gastroenteritis 3% 5%
Paresthesia 4% 5%
Migraine 1% 5%


Warnings and precautions

You should not take Gilenya if you’ve had certain heart problems. Persons who have had a heart attack, unstable angina, a stroke or warning stroke, or certain kinds of heart failure within the last 6 months, should not take Gilenya. Additionally, persons who have certain types of irregular or abnormal heart rhythms (called arrhythmia), including a problem called prolonged QT, or who are taking a medication to correct heart rhythm, should not take Gilenya.

Heart monitoring required when starting Gilenya. Your heart rate may decrease during the first hour after taking the first dose of Gilenya, a condition called bradycardia. Decrease in heart rate usually occurs within 6 hours of starting Gilenya, followed by a recovery of normal heart rate. There may be second period of decreased heart rate within 24 hours of starting Gilenya. Because of these heart rate changes, you should be monitored for the first 6 hours after starting Gilenya treatment. Heart rate generally returns to normal, if Gilenya is taken as recommended, within one month of starting Gilenya.

Risk of infections. Since Gilenya results in a 20% to 30% decrease in lymphocytes (a type of white blood cell that plays an important role in the body’s immune system), there is an increased risk for infections, some serious, with Gilenya therapy.

Risk of macular edema. Macular edema, a condition involving swelling of the part of the eye called the macula, is a rare adverse effect associated with Gilenya. Therefore, if you experience any vision problems while taking Gilenya, you should speak to your doctor and have your vision evaluated.

Liver function problems. Since Gilenya can affect liver function, people who take Gilenya should have period blood tests to monitor liver function.

Risk in pregnancy and nursing. Talk to your doctor if you are taking Gilenya and become pregnant or are planning to become pregnant, as Gilenya may cause harm to the fetus. You should also talk to your doctor if you are taking Gilenya and are nursing. It is not known whether Gilenya can pass through your breast milk to your baby and whether it can harm your baby.


Drug interactions

When Gilenya and the antifungal drug ketoconazole (brand name: Nizoral) are taken together, exposure to Gilenya is increased by 70%, with an increased risk for side effects. Therefore, people taking both medications should be monitored closely.

Because of the increased risk for infections with Gilenya, you should avoid vaccinations while taking Gilenya and for 2 months after stopping the drug.

Starting treatment with Gilenya can cause decreased heart rate and may cause a heart problem called prolonged QT interval. People who are taking drugs that can cause prolonged QT interval, such as citalopram, chlorpromazine, haloperidol, methadone, and erythromycin, should be monitored closely when starting Gilenya.

There have been no studies evaluating the safety of using immunomodulatory, immunosuppressive, or antineoplastic drugs at the same time with Gilenya. Since these drugs may decrease immune system function, taking these types of drugs with Gilenya may increase the risk of immunosuppression and infection.