Safer Using – Heroin

About Heroin

Heroin (AKA diacetylmorphine or diamorphine) is a depressant drug belonging to the semi-synthetic opioid class.1 It goes by many slang names: smack, gear, junk,  horse, slow, H, brown, hammer and Harry.1,2 Heroin is known for its ability to produce intense euphoria, relaxation and pain relief which lasts a few hours.3,4 It can be snorted, smoked, shafted, injected under the skin (subcutaneous), or injected into veins (intravenous or IV).4 If taken by mouth, it is mostly converted into morphine in the liver.4 

In 2023, the Australian Capital Territory decriminalised the possession of small amounts of recreational drugs.5 This means you may receive a health intervention or fine instead of conviction if you’re caught with up to 1 gram of heroin.5 For more information, see this helpful graphic

Heroin is chemically manufactured from morphine, which is naturally produced by the opium poppy (Papaver somniferum).6 This makes heroin a semi-synthetic opioid because it is synthesised from a natural opioid, rather than from scratch. In the body, heroin is converted back into morphine, which is what produces the characteristic euphoria, relaxation, and pain relief.4 However, the small chemical modification means heroin is better able to pass into the brain before it is converted into morphine, causing the effects to be far more intense and short-lived.4 

The chemical structure of heroin is almost identical to morphine apart from the two additional acetyl groups (highlighted in green).  

Heroin primarily comes in two forms: brown heroin (heroin base) and white heroin (heroin salt or heroin hydrochloride).2,7 White heroin is the most common type found in Australia, but brown heroin is more common in the UK and Europe.2,7 White heroin readily dissolves in water making it suitable for injecting.2,7 Brown heroin is less soluble in water and burns at a lower temperature making it more suitable for smoking.2,7 Brown heroin requires the addition of an acid (ideally sterile citric acid or vitamin C) before it can be dissolved in water and injected (see The Safer Injecting Handbook for more info).8 It is often not obvious whether heroin is base or salt based on appearance alone because either type can appear brown or white.2 If it is unusually difficult to dissolve in water, then it is most likely brown heroin.2 

In Australia, the majority of people who use heroin inject it intravenously. The most commonly injected drugs in Australia are heroin and methamphetamine.9 Injecting drugs carries some risks including vein damage, overdose, infection with blood-borne viruses (BBVs), and bacterial infection.8 The spread of BBVs has greatly reduced thanks to the availability of treatments and clean injecting equipment at needle and syringe programs (NSPs).10 However, hygiene, filtering, dosing, and vein care are all very  important elements of harm reduction and sometimes difficult to get right.8,11 

There are many fantastic harm reduction resources for injecting drugs such as AIVL’s Vein Care Guide and The Safer Injecting Handbook. For further information you can contact CAHMA and chat with a non-judgemental health professional about vein care and harm reduction. 

The adulteration of drugs—including heroin—with fentanyl and other synthetic opioids have been major drivers of the overdose crisis in the US and Canada. In Australia, the number of deaths caused by synthetic opioids has increased over the last two decades.12 Moreover, potent synthetic opioids in the nitazene class have recently been detected in heroin samples.13 It is more important than ever to carry naloxone (see section on overdose below) and to test your heroin either by using fentanyl test strips (e.g., or ideally by taking it to a drug checking service such as CanTEST

Effects of Heroin

The effects of drugs can vary from person to person, but the effects of heroin commonly include:3 

  • Euphoria. 
  • Relaxation. 
  • Pain relief. 
  • Constipation. 
  • Sedation, “nodding off” or “nods”. 
  • Suppressed appetite. 
  • Decreased heart rate (bradycardia). 
  • Decreased sex drive. 
  • Itchiness. 
  • Difficulty urinating. 
  • Nausea. 
  • Constricted pupils (miosis). 
  • Dry mouth. 

The effects of heroin will come on almost instantly when injected intravenously, or up to two minutes when snorted.3,14 The effects generally last for 3-5 hours.3,14 

Dosing Heroin

People react differently to drugs due to differences in bodyweight, metabolism, and a range of other factors. It’s also very difficult to determine the potency of drugs sold on the street. Hence, it’s always better to start with a low dose and wait before redosing drugs (start low and go slow). 

The correct dose of heroin to produce your desired intensity of effects depends on the way you consume it.3,14 Tolerance to heroin builds quickly and a larger dose may be required to produce the same intensity of effects following repeated use. Tolerance also fades, so if you’ve taken a break from heroin, start with a dose smaller than you would use previously. The following dosage guides are for someone with no tolerance. 

The following is an approximate dosage guide for intravenously injected heroin:14 


STRONG DOSE – 8-15 mg 

The following is an approximate dosage guide for smoked heroin:3,14 

LOW DOSE – 5-15 mg 

MODERATE DOSE – 15-20 mg 

STRONG DOSE – 20-30 mg 

The following is an approximate dosage guide for snorted heroin:3,14 

LOW DOSE – 5-20 mg 

MODERATE DOSE – 20-35 mg 

STRONG DOSE – 35-50 mg 

Heroin Overdose and Naloxone 

A heroin overdose is life-threatening because it stops a person from breathing properly.15,16 The symptoms of a heroin overdose appear within 10 minutes of injection and typically include:15-17 

  • Loss of consciousness. 
  • Slowed or abnormal breathing. 
  • Low body temperature (hypothermia). 
  • Vomiting. 
  • Low heart rate (bradycardia). 
  • Low blood pressure (hypotension). 
  • Pale, blue-ish, or cold skin (cyanosis). 
  • Choking or gargling noises. 
  • Damage to muscles (rhabdomyolysis). 

If you suspect someone has overdosed on heroin, try waking them up with a loud voice, pinching their shoulder or rubbing your knuckle over their chest. If they don’t respond, call 000 immediately. In the meantime, try to place them in the recovery position and wait with them until they recover. 

If available, naloxone can temporarily reverse the effects of a heroin overdose.18 Naloxone (aka Narcan) is available either as an intranasal spray or as an injectable formulation which comes in a pre-loaded syringe. Naloxone is available for free and without a prescription at NSPs, some pharmacies, and CanTEST as part of the Take Home Naloxone program.18 CAHMA runs regular Overdose Management training workshops where you can learn how to recognize the risks and signs of overdose and how to use naloxone to reverse an opioid overdose. Free take-home naloxone is provided for everyone attending these workshops. 

Naloxone breaks down in the body fairly quickly (30-90 minutes), after which the overdose symptoms may return.19 Hence, it is important to seek emergency medical attention even if you administer naloxone. Naloxone can sometimes cause withdrawal symptoms when given to someone who is opioid-dependent.19 These symptoms will subside after an hour or so as the naloxone wears off. 

Mixing heroin with other drugs can greatly increases the risk of side effects and overdose. For example:3 

  • Mixing heroin with central nervous system depressants (e.g., alcohol, GHB, or benzos) is particularly dangerous as it increases the risk of heavy sedation, memory loss, slow shallow breathing and vomit aspiration.   
  • Mixing heroin with stimulants (e.g., methamphetamine, or cocaine) can cancel out the effects of heroin. This can cause a person to fall into a heroin overdose once the stimulant wears off. 
  • Mixing heroin with tramadol increases the risk of seizures. 

Heroin Withdrawal

Heroin withdrawal is usually not life-threatening, but it can be a very unpleasant experience. The symptoms of heroin withdrawal can vary from person to person and depend on the frequency and length of use, but they often include:19,20 

  • Hot and cold flushes. 
  • Sweating. 
  • Trembling or shaking (tremor). 
  • Nausea and vomiting. 
  • Fast heart rate (tachycardia). 
  • Diarrhea. 
  • Lack of appetite. 
  • Feeling anxious or irritable. 
  • Watery eyes and runny nose. 
  • Sneezing.   
  • Heroin cravings. 
  • Insomnia 
  • Muscle spasms (restless legs) 
  • Abdominal cramps 
  • Feelings of fear or panic 
  • Dysphoria 

Withdrawal symptoms typically begin 6 to 12 hours after stopping heroin use.20 They are generally worst 2 days after stopping and tend to improve after a week or so.20 

If you are concerned about your own heroin use, there is a variety of different treatment options that can help you reduce or stop your heroin use. If you are concerned about the effects of heroin withdrawal, consider seeing a non-judgmental health professional, for example at the CAHMA clinic





[4] Bronwen Bryant and Kathie Knights, Pharmacology for Health Professionals, 4th Edition 

















Written by Darcy Lynch

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