MedlinePlus also includes a Medical Encyclopedia of thousands of articles, videos, and graphics available in English and Spanish. MedlinePlus licenses the Medical Encyclopedia from A.D.A.M. According to the editorial policy “A.D.A.M. content is physician-reviewed and physician-updated, in collaboration with skilled consumer senior medical editors and writers.” To learn more about A.D.A.M, view the A.D.A.M editorial policy.

You can search the Medical Encyclopedia using the A–Z List.

For example, going to the L section, we find an entry on Lactose intolerance.

The Medical Encyclopedia entry for lactose intolerance provides a summary, causes, symptoms, tests, and more. It also links to related MedlinePlus Health Topics, images, and patient instructions.

Scrolling to the bottom of the entry, notice that the source is A.D.A.M.