Heroin is used medically in a small number of countries, most notably the United Kingdom, where it is prescribed under its pharmaceutical name, diamorphine. It is a legal, regulated medication in British hospitals for severe pain, terminal illness, and certain cardiac emergencies. In the United States, however, heroin is classified as a Schedule I controlled substance, meaning federal law considers it to have no accepted medical use and prohibits its prescription entirely.
Where Diamorphine Is Prescribed
The UK is the most prominent example of a country that uses pharmaceutical-grade heroin in clinical medicine. British hospitals stock diamorphine hydrochloride as a standard injectable painkiller, and it appears in national prescribing guidelines alongside morphine and other opioids. Its primary uses include relief of severe pain after surgery, pain management in terminally ill patients (particularly those with cancer), chest pain during a heart attack, and breathlessness caused by fluid buildup in the lungs.
In British cardiology, diamorphine has a long history of use for managing acute heart failure, unstable angina, and the pain of a heart attack. It remains part of the treatment toolkit in those emergency settings. A small number of other countries, including some in continental Europe, have also permitted diamorphine prescribing in limited contexts, but the UK is where its clinical use is most widespread and routine.
Why Hospitals Prefer It Over Morphine
The reason diamorphine has a place in medicine comes down to a practical advantage: it dissolves in water far more easily than morphine does. This high solubility means that even large doses can be delivered in a very small volume of liquid. For patients receiving injections under the skin, as is common in palliative care, this matters a great deal. Morphine requires a larger volume of fluid to deliver the same level of pain relief, and at higher doses those larger injections can themselves become painful.
NHS palliative care guidelines list diamorphine as a preferred option for patients who can no longer swallow oral medication and need a continuous injection via a small pump worn under the skin. The conversion ratio is straightforward: 1 mg of injected diamorphine provides roughly the same pain relief as 3 mg of oral morphine. So a patient taking 120 mg of oral morphine per day would switch to about 40 mg of subcutaneous diamorphine over 24 hours, delivered in a compact, comfortable volume.
How It Is Given in Hospitals
Medical diamorphine is administered by injection only, through three possible routes: into a vein, into a muscle, or under the skin. In palliative care, the subcutaneous route is most common, often through a small battery-powered pump that delivers a steady dose over 24 to 48 hours. This setup lets patients remain at home or in a hospice rather than being tethered to hospital equipment.
For acute emergencies like heart attacks, diamorphine is typically given directly into a vein for the fastest possible relief. In all cases, it is prepared and administered by healthcare professionals in a controlled setting. The drug is mixed with a glucose or saline solution before injection.
Side Effects and Risks
Medically administered diamorphine carries the same core risks as any potent opioid. The most serious concern is respiratory depression, where breathing slows dangerously. This risk increases sharply if the drug is combined with sedatives, alcohol, or cannabis. Memorial Sloan Kettering Cancer Center notes that combining opioids like diamorphine with benzodiazepines (common anti-anxiety medications) has caused severe drowsiness, breathing failure, and death.
Other common side effects mirror those of morphine: nausea, constipation, drowsiness, and confusion. In palliative care, these are generally manageable and considered an acceptable tradeoff for effective pain control in patients with limited life expectancy. Physical dependence develops with regular use, but in the context of terminal illness, that is rarely a clinical concern.
Why It Is Banned in the United States
The U.S. Drug Enforcement Administration classifies heroin as a Schedule I substance, the most restrictive category. The legal criteria for Schedule I are that a drug has “no currently accepted medical use in the United States, a lack of accepted safety for use under medical supervision, and a high potential for abuse.” This classification makes it illegal to manufacture, prescribe, or possess heroin for any purpose, including medicine.
This does not reflect a pharmacological judgment that diamorphine is uniquely dangerous compared to other opioids. American hospitals use other powerful opioids for the same clinical scenarios where the UK uses diamorphine. The ban is a regulatory and political decision rooted in decades of drug policy, not a conclusion that morphine or other alternatives are medically superior. In practice, U.S. patients receiving end-of-life care or recovering from surgery have access to opioids that provide equivalent pain relief, just not this particular one.
Heroin-Assisted Treatment for Addiction
Separate from pain management, a handful of countries use pharmaceutical heroin as a treatment for severe opioid addiction itself. Switzerland pioneered this approach in the 1990s, and programs now operate in Germany, the Netherlands, Canada, and Denmark, among others. In these programs, people with long-standing heroin addiction who have not responded to standard treatments like methadone receive supervised doses of injectable diamorphine at specialized clinics.
The goal is not to cure addiction in a single step but to stabilize patients, reduce illegal drug use, lower overdose deaths, and connect people with health and social services. This use remains controversial and is not permitted in the United States or most other countries.