What causes an overdose?

An overdose, as the name suggests, is when your body receives too much of a drug. While the specifics can vary depending on the substance, the idea is that too much of the drug stops key functions in your brain and/or body, which can endanger your health and may lead to death. For example, during an opioid overdose, opioid receptors in your brain may be so overwhelmed that they stop functioning, which can lead to troubled breathing and, eventually, death.