Dilaudid (hydromorphone hydrochloride) is a potent narcotic analgesic medication that is chemically similar to morphine and provides pain relief by acting as a full agonist at the mu-opioid receptor in the brain and spinal cord. Dilaudid is available only by prescription and is typically used in the hospital setting to manage severe pain after surgery, injury, or other medical procedures. Dilaudid is also used to manage chronic pain in some patients who require continuous pain relief. However, due to its potency and the potential for abuse and dependence, Dilaudid should be used only as directed by a healthcare provider and with caution in patients who have a history of substance abuse or addiction. Dilaudid can cause a range of side effects, including drowsiness, constipation, nausea, and respiratory depression, especially when taken in high doses or for long periods of time.