You make an account on their website

This app is actually very useful. Probably the best in terms of drug indexing and interaction checks (better than micromedex and webMD).

You use their website to create your account (free) then use those credentials to log in.

I dont normally write reviews but the number of people not using the app simply because there is no in-app signup is disappointing.

cam.mcbride about epocrates, v4.5