A partial agonist is a type of drug that binds to a receptor in the body and activates it, but not to the full extent that a full agonist would. This means that while it can produce a biological response, the response is weaker compared to a full agonist. Partial agonists can be useful in situations where a moderate effect is desired, such as in pain management or mental health treatments. These drugs can also act as antagonists in the presence of a full agonist. For example, if a person is taking a full agonist like morphine for pain relief, introducing a partial agonist like buprenorphine can reduce the overall effect of the morphine. This property makes partial agonists valuable in treating addiction, as they can help manage withdrawal symptoms without producing the same high as full agonists.