Two people in the last two days have asked me the same question. Can they become successful medical writers without a science or medical background?
Yes, they can. Medical writers usually fall in one of two categories: scientists or doctors who loved to write and writers who loved medicine.
I was a journalist who loved science, so I decided to get a master's degree in science journalism, where I took both writing and science courses. And this is an important point. Not having a medical background does not impede you to become a medical writer, but you will have to get some science training eventually to be competitive. It doesn't have to be an advanced degree necessarily, but you will have to know what you are writing about.
If you want to become a freelance health writer and have no science training, you can join AMWA and obtain its new Science Fundamentals Certificate, for example.
Many employers, especially in the pharmaceutical and biotech industries, do require their medical writers to have a strong science background. However, if you are willing to learn and are resourceful, you can be a successful consumer-health writer at a hospital, university, organization or as a freelancer.