Hydromorphone, also known as dihydromorphinone, and sold under the brand name Dilaudid among others, is a morphinan opioid used to treat moderate to severe pain.

[17] More common side effects include lightheadedness, dizziness, sedation, itching, constipation, nausea, vomiting, headache, perspiration, and hallucinations.

Simultaneous use of hydromorphone with other opioids, muscle relaxants, tranquilizers, sedatives, and general anesthetics may cause a significant increase in respiratory depression, progressing to coma or death.

[19] A particular problem that may occur with hydromorphone is accidental administration in place of morphine due to a mix-up between the similar names, either at the time the prescription is written or when the drug is dispensed.

This has led to several deaths and calls for hydromorphone to be distributed in distinctly different packaging from morphine to avoid confusion.

Symptoms of overdose include respiratory depression, drowsiness leading to coma and sometimes to death, drooping of skeletal muscles, low heart rate, and decreasing blood pressure.

[38] Hydromorphone also has been administered via nebulization to treat shortness of breath, but it is not used as a route for pain control due to low bioavailability.

[40] Concentrated aqueous solutions of hydromorphone hydrochloride have a visibly different refractive index from pure water, isotonic 9‰ (0·9 per cent) saline and the like, especially when stored in clear ampoules and phials may acquire a slight clear amber discolouration upon exposure to light; this reportedly has no effect on the potency of the solution, but 14-dihydromorphinones such as hydromorphone, oxymorphone, and relatives come with instructions to protect from light.

[41] Battery-powered intrathecal drug delivery systems are implanted for chronic pain when other options are ruled out, such as surgery and traditional pharmacotherapy, provided that the patient is considered a suitable fit in terms of any contraindications, both physiological and psychological.

[43] Previously, an extended-release version of hydromorphone, Palladone, was available before being voluntarily withdrawn from the market after a July 2005 FDA advisory warned of a high overdose potential when taken with alcohol.

[45] The chemical modification of the morphine molecule to hydromorphone results in higher lipid solubility and greater ability to cross the blood–brain barrier to produce more rapid and complete central nervous system penetration.

[52] Hydromorphone is made from morphine either by direct re-arrangement (made by reflux heating of alcoholic or acidic aqueous solution of morphine in the presence of platinum or palladium catalyst) or reduction to dihydromorphine (usually via catalytic hydrogenation), followed by oxidation with benzophenone in presence of potassium tert butoxide or aluminium tert butoxide (Oppenauer oxidation).

The bacterium Pseudomonas putida serotype M10 produces a naturally-occurring NADH-dependent morphinone reductase that can work on unsaturated 7,8 bonds, with result that, when these bacteria are living in an aqueous solution containing morphine, significant amounts of hydromorphone form, as it is an intermediary metabolite in this process; the same goes for codeine being turned into hydrocodone.

[12] It was introduced to the mass market in 1926 under the brand name Dilaudid,[56] indicating its derivation and degree of similarity to morphine (by way of laudanum).

Hydromorphone is known in various countries around the world by the brand names Hydal, Dimorphone, Exalgo, Sophidone LP, Dilaudid, Hydrostat, Hydromorfan, Hydromorphan, Hymorphan, Laudicon, Opidol, Palladone, Hydromorph Contin, and others.

An extended-release version of hydromorphone, called Palladone, was available for a short time in the United States before being voluntarily withdrawn from the market after a July 2005 FDA advisory warned of a high overdose potential when taken with alcohol.

Hydromorphone is listed under the German Betäubungsmittelgesetz as a Betäubungsmittel in the most restricted schedule for medicinal drugs; it is controlled similarly in Austria (Suchtgift) under the SMG and the Swiss BetmG.

The Misuse of Drugs Act 1971 (United Kingdom) and comparable French, Canadian, Australian, Italian, Czech, Croatian, Slovenian, Swedish, Polish, Spanish, Greek, Russian, and other laws similarly control it, as do regulations in virtually all other countries.

Wood was heavily sedated (surgical anesthesia) within four minutes from start, but took almost two hours to transition to stage 4 (cessation of respiration) and death.