Pills are one-time-use items that are (obviously) in the form of medicine in-game. The pills come in a range of colors and the effects of the pills will change each playthrough. If you pick up a pill and are brave enough to use it, you will be instantly informed of what you have done to yourself and the pill will be named each time you pick it up for that play through.
Trinkets affecting pills- Safety Cap
Items affecting pills- PhD