Medical confusion

“Posologia: 4 x dia inicia apos cirurgia”
The difference between “depois” and “após”.

They both mean after but one has more urgency than the other apparently.
The problem for us was that we were supposed to take a medication right after the surgery (same day) and not the next day. We asked Portuguese family members the difference and they didn’t know. It turns out that we made a big mistake by not taking the medication on the same day. Luckily the doctor said (surprisingly to him) there was no damage done.
Is there a medical glossary of some kind?

@chod.lang, glad to hear no harm was done! Após isn’t inherently more urgent than depois; they’re generally interchangeable. To express a bit more urgency/immediacy, we can say, for example, logo após/logo depois (right after). That could’ve helped in this case. In my opinion, if the timing for this medication was so sensitive, it was your doctor’s responsibility to make sure you understood that clearly before walking out.