When you stub your toe on the bed you’re activating mechanoreceptors on nerve endings that tell your brain you’re in pain. Simple pain medications ( paracetamol, NSAIDs) turn down nerves via reducing inflammatory markers which activate these nerves. Opioids reduce the firing of nerves so they would reduce the pain felt from banging your toe. It’s why patients are given opioids before surgery so they don’t react to the surgeons scalpel