Every week I receive emails asking about online courses for medical writers. The fact is, there are very few options right now.
If you want to get serious with your training, then there's the USP Biomedical Writing Program, which can be taken online. You can earn a master's degree. Read here about one student's experience with this program.
Of course, there is my new site, MedicalWritingTraining.com, which is currently offering two online courses: Epidemiology and Biostatistics for Medical Writers, and Consumer Health Writing. Soon we will have a new course on creating CME materials and later this year, an introductory course on Regulatory Writing. You'll receive certificates of completion for every course at MedicalWritingTraining.com.
AMWA's certificates are the best in the field, but they must be taken on-site (at chapter or annual conferences). They offer just a few self-study workshops.
If you surf around the web, you may find other on-site courses in London, Pennsylvania and California.