Encouraging news for people who suffer with migraines: in May, the FDA approved erenumab (Aimovig), the first medication aimed at preventing these debilitating headaches. Current medications to treat migraines were actually designed to control other conditions, such as seizures or an irregular heartbeat; their side effects (like sexual dysfunction and fuzzy thinking) often cause people to skip treatment. Erenumab offers a new approach. Injected once a month, it works by blocking a molecule (calcitonin gene-related peptide) involved in migraine attacks, and compared with other drugs, it appears to have fewer side effects (primarily constipation and injection site reactions). "This drug is for people who have more than four migraines per month, but it won't take migraines away entirely," says Dr. Gad Marshall, a neurologist at Harvard-affiliated Brigham and Women's Hospital. Clinical trials suggest it can reduce frequency by one or two migraines per month, or even more in some people. "For people with frequent debilitating migraines it could be a game changer," says Dr. Lee Schwamm, a neurologist at Harvard-affiliated Massachusetts General Hospital. "But erenumab is expensive, and it will take time to find out if it's effective and safe over the long term."