• Heroin is a depressant drug – it slows down certain functions of a person’s brain and nervous system.
  • Some of the immediate effects of heroin include feelings of wellbeing and relief from physical pain.
  • Heroin is highly addictive – a person’s body adapts to regular heroin use and may come to depend on the drug to function ‘normally’.
  • For some people who are dependent on heroin, nothing else in life matters except the drug.
Heroin is an illegal substance in the opioid class. (Other opioids include morphine, codeine, pethidine, buprenorphine and methadone.) Heroin is made from the sap of the opium poppy. It is highly addictive and people who use it can become dependent and experience cravings. Initial effects include feelings of wellbeing and relief from physical pain.

One of the adverse effects of using heroin is the risk of overdose. Longer-term use can cause significant health and lifestyle problems. 
Dealers usually mix or ‘cut’ heroin with other substances – such as sugar, paracetamol or caffeine– to boost their profits. This means that the person using heroin has no idea if the dose will be strong or weak.Heroin generally takes the form of granules or powder, and can range in colour from white to brown. Users generally inject it intravenously (into a vein), but they can also snort or smoke it. Common slang terms for heroin include ‘smack’, ‘horse’ and ‘hammer’.

How heroin works

Heroin is a central nervous system depressant. This means it slows down a person’s brain function and affects their breathing (which can slow down or even stop). The person’s body temperature and blood pressure drop, and their heartbeat can become irregular. The person may lose consciousness or lapse into a coma. Ambulance officers, family and friends can give the medication naloxone to reverse the effects of heroin.In February 2016, naloxone was rescheduled to be made available for purchase over the counter. Talk with your pharmacist for more information.

Effects of heroin

The effects of heroin depend on:

  • the strength of the dose
  • the size, weight, general health and state of mind of the person taking the heroin
  • the effects of other drugs and medication that they might have taken at the same time (or even in the last two days).

If the person has taken other depressants such as sleeping pills, tranquillisers, methadone or alcohol, the effects of heroin are increased. This can result in coma or even death.

Some of the immediate effects of taking heroin include: 

  • a rush of pleasurable feelings and relief from physical pain
  • feeling sick or vomiting
  • shallow breathing, drowsiness and sleepiness
  • a drop in body temperature
  • narrowing of the pupils
  • loss of sex drive.

Symptoms of heroin overdose

One of the most dangerous adverse effects of heroin use is the risk of overdose. The symptoms of overdose include: 

  • dangerously low body temperature
  • slowed breathing
  • blue lips and fingernails
  • cold, clammy skin
  • convulsions and coma.

What to do if you suspect an overdose

If someone who has taken drugs does not respond when you talk to them, is snoring loudly or making gurgling noises, they may be in a coma and having trouble breathing. Do not assume that they are just ‘sleeping off’ the effects. Their airway may be blocked by their tongue falling back or other blockages.

This is a medical emergency. If you can’t wake them, dial triple zero (000) to call an ambulance immediately.

Heroin dependence and tolerance

As with some other drugs, a person can build up a tolerance to heroin. After only a short time, the person using heroin will need to take larger doses to achieve the same effect. Soon their body will start to depend on heroin in order to function ‘normally’.

For some people who are dependent on heroin, nothing else in life matters except the drug. They may ignore their career, relationships and even basic needs like eating. Financial, legal and other personal problems may be related to heroin use. The person craves the drug and this psychological dependence makes them panic if they cannot have it, even temporarily.

Symptoms of heroin withdrawal

Withdrawal symptoms can start after a matter of hours without a dose of heroin. They may include: 

  • cravings
  • diarrhoea and vomiting
  • stomach cramps
  • sweating
  • bone, joint and muscle pain and twitching
  • mood swings and crying. 

Damage caused by long-term heroin use

Using heroin on a regular basis can lead to major health and lifestyle problems including: 

  • collapsed veins and skin abscesses
  • risk of contracting various blood-borne viruses, such as HIV and hepatitis, or blood poisoning from sharing needles and other injecting equipment, or using dirty or contaminated equipment
  • chronic constipation
  • increased risk of contracting pneumonia and other lung problems
  • fertility problems
  • disturbances of the menstrual cycle for women
  • impotence for men
  • poor nutrition and reduced immunity
  • loss of relationships, career and home as the person’s need for the drug becomes all-consuming
  • damage to the blood vessels that lead to the lungs, liver, kidneys and brain due to the additives mixed with heroin 
  • risk of overdose.

Treatment for heroin addiction

Treatment options for heroin addiction include: 

  • detoxification
  • individual counselling
  • group therapy
  • medication programs such as methadone, buprenorphine or naltrexone.


Where to get help

  • In an emergency, always call triple zero (000)
  • Your doctor – for information or referral to a drug treatment service
  • Alcohol and drug treatment services – for help with dependence, detoxification, individual counselling and group therapy
  • DrugInfo. Tel. 1300 85 85 84 – for information
  • DirectLine. Tel. 1800 888 236 – for 24-hour confidential drug and alcohol telephone counselling, information and referral
  • Family Drug Help. Tel. 1300 660 068 – for information and support for people concerned about a relative or friend using drugs 

More information


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Types of drugs

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This page has been produced in consultation with and approved by: Alcohol and Drug Foundation

Last updated: June 2017

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