[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Drugs of abuse](https://durgical.com/en/pharmacology/classes/drugs-of-abuse/) › Diamorphine (heroin)

# Diamorphine (heroin)

## Drugs of abuse?

Drugs of abuse

Heroin: an opioid made from morphine. A rush, then drowsiness and slowed breathing; overdose kills by respiratory arrest and responds to naloxone.

Updated Nov 12, 2026

Also called: Heroin, Diacetylmorphine

## Quick facts

**Group**
[Drugs of abuse](https://durgical.com/en/pharmacology/classes/drugs-of-abuse/)

**Target**
Mu-opioid receptor (after conversion to morphine)

**Used for**
Clinical relevance · Clinical relevance

**Key effects**
Rush with warm flushing of the skin · Nausea

**Monitor**
Airway · Pupils and response to naloxone · Temperature

**ATC**
N07BC06

No doses: the clinician sets them by the current guideline.

On this page

- The basics Mechanism of action
- Indications
- Adverse effects
- Pharmacokinetics
- Memory aid

- Safety Contraindications
- Key interactions
- What is monitored
- Pregnancy and breastfeeding
- Nursing care

- Study Test yourself

- Connections Connections

## Mechanism of action

◎**Mu-opioid receptor (after conversion to morphine)**Diamorphine (heroin)

ⓘ The figure shows morphine, into which heroin is converted in the brain, bound to the human mu-opioid receptor with its Gi protein.

**Target in 3D:** Mu-opioid receptor (after conversion to morphine). PDB structure 8EF6 (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/8EF6) · Drag to rotate · pinch to zoom

Diamorphine is morphine with two acetyl groups, which make it more fat-soluble, so it enters the brain faster than morphine. There it is converted to morphine (via 6-monoacetylmorphine), which activates mu-opioid receptors. The fast rise gives an intense 'rush'. Mu receptors in the limbic system reinforce use; in the spinal cord they block pain; in the brainstem they depress the response to carbon dioxide, so breathing slows and can stop.

- Fat-soluble: crosses into the brain very fast
- Converted to morphine there
- Mu-opioid receptors: rush, reward, analgesia
- Brainstem: breathing slows and may stop

## Indications

- Clinical relevance: opioid overdose with coma, pinpoint pupils and slow breathing [Opioid overdose →](https://durgical.com/en/conditions/opioid-overdose/)
- Clinical relevance: opioid use disorder [Opioid use disorder, overdose and withdrawal →](https://durgical.com/en/conditions/opioid-use-disorder-overdose-and-withdrawal/)

## Adverse effects

### Common

- Rush with warm flushing of the skin, dry mouth and heavy limbs
- Nausea, vomiting, severe itching
- Drowsiness and clouded thinking ('nodding')
- Constipation, insomnia; irregular periods and sexual dysfunction with chronic use

### Serious (rare, important)

- Overdose: very slow breathing, coma, brain damage and death
- Opioid use disorder, with withdrawal (pain, diarrhoea, nausea, vomiting) on stopping
- Injection complications: collapsed veins, abscesses, endocarditis; HIV and hepatitis B and C from shared equipment
- Pneumonia and other lung complications; nasal septum damage when snorted

## Contraindications

- No safe non-medical use
- Especially dangerous with alcohol, benzodiazepines or other sedatives, after a period of abstinence (lost tolerance), or when mixed with unknown adulterants

## Key interactions

**Alcohol, benzodiazepines and other CNS depressants**
Deeper sedation and respiratory depression.

**Naloxone**
Rapidly reverses the opioid effects, including breathing depression; it can also precipitate withdrawal.

**Naltrexone**
Blocks opioid effects; used in treatment after detoxification.

## What is monitored

- Airway, breathing rate, oxygen saturation and level of consciousness
- Pupils and response to naloxone; re-sedation as naloxone wears off
- Temperature, injection sites, heart murmurs (endocarditis)
- HIV, hepatitis B and C testing

## Pregnancy and breastfeeding

Use in pregnancy can cause neonatal abstinence syndrome; methadone or buprenorphine with prenatal care improves outcomes for mother and baby.

## Nursing care

- Support breathing first (bag-mask ventilation, oxygen), then give naloxone as ordered.
- Observe after naloxone: its effect can end before the opioid's, and breathing can slow again.
- Treat withdrawal symptoms and offer medicines for opioid use disorder (methadone, buprenorphine, naltrexone).
- Teach naloxone use to family and friends; refer for testing and harm reduction.

## Pharmacokinetics

**Absorption**
Injected, smoked or snorted; white or brown powder or sticky 'black tar'.

**Metabolism**
Rapidly converted to 6-monoacetylmorphine and morphine.

**Onset and duration**
The rush comes within moments when injected or smoked; drowsiness lasts several hours.

## Memory aid

Opioid overdose triad: Coma, Pinpoint pupils, slow breathing; the answer is Naloxone and ventilation.

## Test yourself

Think of the answer, then tap the question to see it.

## Why does heroin reach the brain faster than morphine?

Its two acetyl groups make it more fat-soluble; in the brain it is converted back to morphine.

## What is the classic triad of opioid overdose?

Coma, pinpoint pupils and respiratory depression.

## Why must a patient be watched after naloxone reverses a heroin overdose?

Naloxone may wear off before the opioid does, and breathing can slow again.

## Which infections are linked to sharing injection equipment?

HIV and hepatitis B and C (also bacterial endocarditis and abscesses from injection).

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/pharmacology/diamorphine/)

[More Pharmacology questions →](https://durgical.com/en/practice/?f=pharmacology)

## Connections

## Related drugs 5

- [Morphine](https://durgical.com/en/pharmacology/morphine/)
- [Naloxone](https://durgical.com/en/pharmacology/naloxone/)
- [Methadone](https://durgical.com/en/pharmacology/methadone/)
- [Buprenorphine](https://durgical.com/en/pharmacology/buprenorphine/)
- [Fentanyl](https://durgical.com/en/pharmacology/fentanyl/)

## Related conditions 2

- [Opioid overdose](https://durgical.com/en/conditions/opioid-overdose/)
- [Opioid use disorder, overdose and withdrawal](https://durgical.com/en/conditions/opioid-use-disorder-overdose-and-withdrawal/)

[← Back to the class: Drugs of abuse](https://durgical.com/en/pharmacology/classes/drugs-of-abuse/)

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [What are the immediate (short-term) effects of heroin use?](https://nida.nih.gov/publications/research-reports/heroin/what-are-immediate-short-term-effects-heroin-use) (National Institute on Drug Abuse (NIDA), 2026); [What are the medical complications of chronic heroin use?](https://nida.nih.gov/publications/research-reports/heroin/what-are-medical-complications-chronic-heroin-use) (National Institute on Drug Abuse (NIDA), 2026); [What can be done for a heroin overdose?](https://nida.nih.gov/publications/research-reports/heroin/what-can-be-done-for-heroin-overdose) (National Institute on Drug Abuse (NIDA), 2026); [How does heroin use affect pregnant women?](https://nida.nih.gov/publications/research-reports/heroin/how-does-heroin-abuse-affect-pregnant-women) (National Institute on Drug Abuse (NIDA), 2026).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/pharmacology/diamorphine/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/diamorphine/