Side Effects je karetní "take that" hra, ve které se hráči pokusí jako první vyléčit všechny své nemoci.
Players start with four disease cards dealt face up in front of them (their "psyche") and then four cards in a concealed hand. Players take turns picking up cards from the deck and trying to find the right drugs to treat their diseases. A drug card will treat a disease but also leave the player open to receiving new diseases (of that drug's list of side effects) from other players.
Each disease card has a unique punishment written on it and episode cards will trigger these punishments. Play an episode card on another player to hinder them or help yourself.
The game is over when one player treats all of the diseases in their psyche.