In the United States, fingolimod must be dispensed with a medication guide that contains important information about its uses and risks. Serious risks include slowing of the heart rate, especially after the first dose. Fingolimod may increase the risk of serious infections. Patients should be monitored for infection during treatment and for two months after discontinuation of treatment. A rare brain infection that usually leads to death or severe disability, called progressive multifocal leukoencephalopathy (PML) has been reported in patients being treated with the drug. PML cases usually occur in patients with weakened immune systems. Fingolimod can cause vision problems. It may increase the risk for swelling and narrowing of the blood vessels in the brain (posterior reversible encephalopathy syndrome). Other serious risks include respiratory problems, liver injury, increased blood pressure and skin cancer. Fingolimod may cause harm to a developing fetus; health care professionals should advise women of child-bearing age of the potential risk to the fetus and to use effective contraception.