Gilenya has been prescribed because your healthcare provider has judged that the benefits are greater than the risk of side effects. Many people using this medication do not have serious side effects. 

Gilenya may cause serious side effects, including:

Increased risk of infections

Call your doctor right away while on treatment with Gilyena and for two months after the last dose if you have any of the symptoms indicating an infection

• fever
• tiredness
• body aches
• chills
• nausea
• vomiting
• headache along with fever, neck stiffness, sensitivity to light, nausea, or confusion (these may be symptoms of meningitis)

Progressive multifocal leukoencephalopathy (PML)

PML is a rare brain infection that can lead to death or severe disability. Call your healthcare provider immediately if you experience any new or worsening symptoms of PML that have lasted several days, including:

• weakness on one side of your body
• loss of coordination in your arms and legs
• decreased strength
• problems with balance
• changes in your vision
• changes in your thinking or memory
• confusion
• changes in your personality

Disturbed vision due to macular edema. 

Macular edema can also be caused by MS due to optic neuritis. It may be difficult to notice vision changes during treatment with Gilenya. Call your healthcare provider immediately if you experience any of the following:

• blurriness or shadows in the center of your vision
• a blind spot in the center of your vision
• sensitivity to light
• unusually colored (tinted) vision

Posterior Reversible Encephalopathy Syndrome (PRES)

PRES is caused by swelling and narrowing of the blood vessels in the brain. Call your healthcare provider immediately if you experience any new or worsening symptoms of PRES that have lasted several days, including:

• sudden severe headache
• sudden confusion
• sudden loss of vision or other changes in your vision
• seizure

Liver damage

Gilenya may cause liver damage. Call your healthcare provider immediately if you experience any new or worsening symptoms of liver damage such as:

• nausea
• vomiting
• stomach pain
• tiredness
• loss of appetite
• jaundice (the skin or the whites of the eyes turn yellow)
• dark urine

Breathing problems

Some people who take Gilenya experience shortness of breath. Call your healthcare provider right away if you have new or worsening breathing problems.

Skin cancer such as basal cell carcinoma (BCC) and melanoma 

Tell your doctor if you have any of the following changes in the appearance of your skin:

• changes in a mole
• a new darkened area on your skin
• a sore that does not heal
• growths on your skin, such as a bump that may be shiny, pearly white, skin-colored, or pink. 

Allergic reactions. 

Call your healthcare provider right away if you have symptoms of an allergic reaction, such as:

• a rash
• itchy hives
• swelling of the lips, tongue or face.

Common side effects

The more common side effects of Gilenya include:

• headache
• diarrhea
• cough
• flu
• inflammation of the sinuses (sinusitis)
• back pain
• abdominal pain
• pain in the arms or legs

These side effects should clear-up within a few days. If they persist or get worse, refer back to your healthcare provider or pharmacist.

Gilenya is prescribed to treat relapsing forms of multiple sclerosis (MS), to include clinically isolated syndrome (CIS), relapsing-remitting MS (RRMS), and active secondary progressive MS (SPMS), in adults and children ten years of age and older.
It may also be used in chronic inflammatory demyelinating polyneuropathy.