There's four types of damage.
Brute damage is like getting stabbed or beaten. It's treated with bruise packs.
Burn damage is from fire and bombs. It's treated with ointment.
Suffocation damage happens when you black out, go into an airless area without a gas mask, or go into space without a space suit. It goes away by itself over time.
Toxin damage happens when you breathe plasma, eat lots of antitoxin pills, eat cyanide, or many other things. It's treated with antitoxin pills and Antitoxin suppliments.