The risks and effects of heroin

Aka: Smack, gear, H, skag, junk, brown, horse, china white
Written by

Remember: All drugs, including the misuse of prescribed medication, can pose serious health risks, up to and including possible death.

Heroin is a powerful and very addictive drug. It is a pain-killing drug made from morphine, which is derived from the opium poppy. Street heroin is usually a brown/white powder, smells acidic and is usually mixed with other substances.

It is smoked, sniffed, or dissolved in water and injected.

The effects of heroin

  • Effects of heroin last for two to three hours
  • The initial rush is followed by a dreamlike state of peacefulness and contentment 
  • Pain is reduced, as are aggressive tendencies and sexual drive (horniness)
  • First time use (especially if injected) often causes severe nausea and vomiting and severe headaches

The risks of taking heroin

There are a lot of risks associated with taking heroin. It’s very important to be aware of the risks you take in trying any drug.


Heroin is a very addictive drug – experimenting with heroin means risking becoming addicted, and it can be very difficult to overcome. 

However, there is help available for addiction. Find out more about getting help for addiction here.

Risk of overdose

Larger doses of heroin can lead to drowsiness and excessive doses can result in overdose and coma. It can also be fatal.

If you have been taking heroin regularly you may have built up tolerance, but if you then stop taking it for just for a few days, your tolerance will rapidly drop – and you risk an overdose if you take the same high dose you previously took.

If heroin is taken with other drugs, including alcohol, an overdose is more likely.

Risk of infection

Sharing needles when injecting heroin leaves users at risk of infection, e.g. Hepatitis B and HIV from contaminated needles, syringes and other injection equipment with other users. If you do take Heroin, it’s really important that you inject as safely as possible. Check out Merchant Quay’s guide to safer injecting.


It is also difficult to withdraw from this drug. Users trying to kick the habit may experience withdrawal symptoms. Withdrawal begins between 8 and 24 hours after the last “fix” of heroin.

Symptoms can include:

  • Aches
  • Tremors
  • Sweating
  • Chills
  • Anxiety
  • Irritability
  • Loss of appetite
  • Muscular spasms
  • Yawning and sneezing
  • Hot and cold sweats and cramps

Heroin and the law

Heroin is controlled by the Misuse of Drugs Act. It is illegal to possess it unless prescribed by a doctor and supplied by a pharmacist. It is an offence to import, distribute, produce or sell it.

Supports and Services

  • Online information and support for drug and alcohol use. Includes a national directory of drug and alcohol services
  • HSE Drugs, Alcohol, HIV and Sexual Health Helpline: Freephone 1800 459 459.
  • The Club Drug Clinic offers advice, support and detoxification for GHB (Liquid Ecstasy, G) and other chemsex and club drugs is an integrated person centred specialist addiction service: Tel 016488600
  • Rialto Community Drug Team
  • Find a local service through the National Directory for Drug and Alcohol Services at
Related articles
Skip to content