Koffein er da absolutt et rusmiddel, den har en merkbar ruseffekt og stort potensiale til avhengighetsdannelse.

Utdrag fra den engelske wikipediaartikkelen på koffein:

In humans, caffeine acts as a central nervous system stimulant, temporarily warding off drowsiness and restoring alertness. It is the world's most widely consumed psychoactive drug, but, unlike many other psychoactive substances, it is legal and unregulated in nearly all parts of the world.