Qualifications
Medical writers typically have degrees in the life sciences and/or communication. Maybe they start out with a bachelor's degree in chemistry, realize that research isn't their cup of medicinal tea, and take graduate classes in journalism or marketing. Or maybe the opposite is true, and a journalism major who gleefully dissected frogs during a science elective ends up getting a master’s in regulatory science (source).
Or maybe they're a Mr. (or Ms. or Señor or Duke) Ambitious, and take both science and writing courses in college—then a bachelor's degree just might do it.
But, humanities majors, fear not. You can take post-collegiate medical writing courses. Some companies will even require their medical writers to get a certificate from the American Medical Writers Association, which offers medical writing workshops. But remember, medical writing careers live or die by how good the words are that end up on the page (or on computer screens).
Speaking of computers, medical writers must have stellar computer skills, as their work will generally involve Microsoft Word. They should also know electronic publishing. Some companies want medical writers to be bilingual (good skill to have in case you run across documents written in Urdu and, by golly, you majored in Indian languages).