The Food and Drug Administration (FDA) recently approved a new drug, called Emgality, intended to prevent migraines rather than just treat them.

Emgality, produced by pharma giant Eli Lilly (NYSE: LLY), is the third among a series of preventative migraine drugs that hacks migraine at its core by attacking the calcitonin gene-related peptide (CGRP). The CGRP is a neurotransmitter, found throughout the brain and body, plays a key role in migraines.

How do we know Emgality works?

Researchers tested Emgality in three studies where one group of 106 patients, with between four to 14 migraines a month, received the monthly injection, while the other group—the same number of people with similar conditions—received a placebo.