Illicit heroin is sometimes available in freebase form, dulling the sheen and consistency to a matte-white powder.^[7] Because of its lower boiling point, the freebase form of heroin is alsosmokable. It is prevalent in heroin coming from Afghanistan, which in 2004 produced roughly 87% of the world supply in illicit raw opium.^[8] However, the production rate in Mexico has risen sixfold from 2007 to 2011, changing that percentage and placing Mexico as the second largest opium producer in the world.^[9]

As with other opioids, diacetylmorphine is used as both an analgesic and a recreational drug. Frequent and regular administration is associated with tolerance and physical dependence. Internationally, diacetylmorphine is controlled under Schedules I and IV of the Single Convention on Narcotic Drugs.^[10] It is illegal to manufacture, possess, or sell diacetylmorphine without a license in almost every country, except the UK and Switzerland.^[11]

It is also available for prescription to long-term users as a form of opioid replacement therapy in the United Kingdom, Netherlands, Switzerland, Germany, and Denmark, alongsidepsycho-social care—in the same manner that methadone or buprenorphine are used in the United States and Canada—and a similar programme is being campaigned for by liberal political parties in Norway.^[12]

Under the chemical name diamorphine, diacetylmorphine is prescribed as a strong analgesic in the United Kingdom, where it is given via subcutaneous, intramuscular, intrathecal orintravenous route. Its use includes treatment for acute pain, such as in severe physical trauma, myocardial infarction, post-surgical pain, and chronic pain, including end-stage cancerand other terminal illnesses. In other countries it is more common to use morphine or other strong opioids in these situations. In 2004, the National Institute for Health and Clinical Excellence, a non-departmental public body of the Department of Health in the United Kingdom, produced guidance on the management of caesarian section, which recommended the use of intrathecal or epidural diacetylmorphine for post-operative pain relief.^[16]

In 2005, there was a shortage of diacetylmorphine in the UK, because of a problem at the main UK manufacturers.^[17] Because of this, many hospitals changed to using morphineinstead of diacetylmorphine. Although there is no longer a problem with the manufacturing of diacetylmorphine in the UK, some hospitals there have continued to use morphine. The majority, however, continue to use diacetylmorphine, and diacetylmorphine tablets are supplied for pain management.

Diacetylmorphine continues to be widely used in palliative care in the UK, where it is commonly given by the subcutaneous route, often via a syringe driver, if patients cannot easily swallow oral morphine solution. The advantage of diacetylmorphine over morphine is that diacetylmorphine is more fat soluble and therefore more potent by injection, so smaller doses of it are needed for the same analgesic effect. Both of these factors are advantageous if giving high doses of opioids via the subcutaneous route, which is often necessary in palliative care.

The medical use of diacetylmorphine, in common with other strong opioids such as morphine, fentanyl and oxycodone, is controlled in the UK by the Misuse of Drugs Act 1971. In the UK, it is a class A controlled drug and as such is subject to guidelines surrounding its storage, administration and destruction. Possession of diamorphine without a prescription is an arrestable offence. When diamorphine is prescribed in a hospital or similar environment, its administration must be supervised by two people who must then complete and sign a controlled drugs register (CD register) detailing the patient's name, amount, time, date and route of administration. In the case of a physician administering diamorphine, then he/she may administer the drug alone, however the rule requiring two registered practitioners, such as a nurse, midwife or another physician to sign the CD register still applies. The use of a witness when administering diamorphine is to avoid the possibility of the drug being diverted onto the black market.

For safety reasons, many UK National Health Service hospitals now only permit the administration of intravenous diamorphine in designated areas. In practice this usually means a critical care unit, an accident and emergency department, operating theatres by an anaesthetist or nurse anaesthetist or other such areas where close monitoring and support from senior staff is immediately available. However, administration by other routes is permitted in other areas of the hospital. This includes subcutaneous, intramuscular, intravenously as part of a patient controlled analgesia setup, and as an already established epidural infusion pump. Subcutaneous infusion, along with subcutaneous and intramuscular injection (bolus administration) is often used in the patient's own home, in order to treat severe pain in terminal illness.