Strong opioid (heroin) Pregnancy: Regular use during pregnancy may cause drug dependence in the foetus, leading to withdrawal symptoms in the neonate; if opioid use is required for a prolonged period, advise the patient of the risk of neonatal opioid withdrawal syndrome and ensure appropriate treatment will be available. Administration during labour may depress respiration in the neonate and an antidote for the child should be readily available. Administration to nursing women is not recommended as diamorphine may be secreted in breast milk and may cause respiratory depression in the infant.

Diamorphine hydrochloride

Brand names: various

Diamorphine (heroin) is a potent opioid analgesic used in the UK for severe pain, including in palliative care, acute pain and myocardial infarction.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: Acute pain: 5 mg repeated every four hours if necessary (up to 10 mg for heavier, well muscled patients) by subcutaneous or intramuscular injection. By slow intravenous injection, one quarter to one half of the corresponding intramuscular dose.

Route: Subcutaneous, intramuscular or intravenous injection (also given by continuous infusion pump over 24 to 48 hours)

Frequency: Every four hours if necessary

The dose should be suited to the individual patient. Chronic pain: 5 to 10 mg regularly every four hours by subcutaneous or intramuscular injection; the dose may be increased according to individual needs. Myocardial infarction: 5 mg by slow intravenous injection (1 mg/minute) followed by a further 2.5 mg to 5 mg if necessary. Acute pulmonary oedema: 2.5 mg to 5 mg by slow intravenous injection (1 mg/minute). Diluent: glucose intravenous infusion is the preferred diluent, particularly when administered by a continuous infusion pump over 24 to 48 hours, although diamorphine is also compatible with sodium chloride intravenous infusion. Children and elderly: as diamorphine has a respiratory depressant effect, care should be taken when giving the drug to the very young and the elderly and a lower starting dose than normal is recommended — the SPC gives no numeric paediatric dose, so any paediatric use must be checked against a children's formulary and specialist advice. Hepatic impairment and debilitated patients: a reduction in dosage should be considered. Prior to starting opioid treatment, discuss and put in place a strategy for ending treatment to minimise the risk of addiction and drug withdrawal syndrome.

Dose adjustments

Renal

The dosage should be reduced in moderate to severe renal impairment.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Acute respiratory depression
Hypersensitivity to the active substance or to any of the excipients
Phaeochromocytoma (endogenous release of histamine may stimulate catecholamine release)
Biliary colic
Coma; raised intracranial pressure; head injuries (increased risk of respiratory depression that may elevate CSF pressure, and sedation/pupillary changes may interfere with monitoring)
Acute alcoholism
Risk of paralytic ileus, or acute diarrhoeal conditions associated with antibiotic-induced pseudomembranous colitis or diarrhoea caused by poisoning (until the toxic material has been eliminated)

Side effects

Respiratory depression — the most serious hazard of therapy
Sedation, nausea and vomiting, constipation and sweating — the most common side effects; tolerance generally develops with long-term use, but not to constipation
Dizziness, vertigo, mental clouding, confusion (with large doses), hallucinations, headache, mood changes including dysphoria and euphoria
Orthostatic hypotension, facial flushing, palpitations, tachycardia, bradycardia
Urinary retention, difficulty with micturition, ureteric spasm, antidiuretic effect; dry mouth, biliary spasm; miosis and blurred or double vision
Drug dependence and drug withdrawal syndrome; rash, pruritus, urticaria; rare anaphylactic reactions following intravenous injection

Clinical monograph

How it works

It is a prodrug rapidly converted to active opioids including morphine, which act as agonists at mu opioid receptors to produce analgesia and other opioid effects.

Prescribing in practice

It is a potent opioid that can cause life-threatening respiratory depression and is liable to misuse and dependence, so prescribe with appropriate caution and observe controlled drug requirements.
Its high solubility allows large amounts to be given in a small volume, which is useful for subcutaneous infusion in palliative care but increases the consequences of dosing errors.
Doses should be reduced and titrated carefully in the elderly, the frail and those with renal or hepatic impairment, with naloxone available to reverse overdose.

Monitoring

Monitor pain control, level of sedation, respiratory rate and bowel function, with closer observation when initiating or increasing the dose.

Counselling the patient

It may cause drowsiness and impair driving and skilled tasks.
Constipation is common, so a laxative is often needed.
Do not take with alcohol or other sedating medicines without advice.

Evidence & guidelines

Diamorphine is a long-established opioid analgesic supported by extensive clinical use in severe and palliative pain.

Reference: NICE NG31; APM Guidelines; FPM Opioids Aware; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways