Pain is a sensation that is transmitted from an area of tissue damage or stress along the sensory nerves to the brain. The brain interprets the information as the sensation of pain.

Substances that decrease pain either interfere with the ability of nerves to conduct messages, or alter the brain’s capacity to receive sensations.

Pain may be a symptom of an underlying pathological condition, such as inflammation. It may also be due to other causes, such as bruising, infection, burns, headaches, and sprains and strains. Use caution when treating pain without understanding its cause—this may delay diagnosis of conditions that could continue to worsen without medical attention.