Heroin is an illegal, highly addictive type of opioid. It is a white or brown powder or a black, sticky substance (black tar heroin). It can be sniffed, snorted, smoked, or injected into a muscle or vein. Other names for heroin are smack, junk, H, and ska.

Heroin is often used along with other drugs, especially cocaine and alcohol. Some people snort alternate lines of heroin and cocaine (crisscrossing). Or they may inject it with another drug (speedball). Heroin is often mixed (cut) with other drugs or things such as sugar or powdered milk. It may also be cut with poisons, such as strychnine.

Effects of heroin

The pleasurable sensation from heroin is called a rush. The intensity of the rush depends on how much was taken and how rapidly the drug entered the brain. When a person injects heroin directly into a vein or smokes heroin, the rush occurs within seconds. It takes at least 10 minutes when the drug is sniffed.

Along with the rush, the person using heroin usually has a warm flushing of the skin, small pupils, watery eyes, runny nose, dry mouth, and a heavy feeling in the arms and legs. Heroin may also cause nausea, vomiting, and severe itching. Soon after the rush, the person feels drowsy and very relaxed. Breathing and heart rate slow. Thinking becomes cloudy. The person may fall into a state like a trance. This can last 4 to 6 hours.

Problems of heroin use

With repeated use, heroin causes the person to need higher and higher doses of the drug to get the same effect. This is called tolerance. The body may also get used to the drug. This is called physical dependence. Physical dependence can develop within a few weeks if the drug is used daily. This leads to uncomfortable withdrawal symptoms within a few hours if the person stops using heroin or uses less.

Addiction can develop within a few weeks if the drug is used daily. Heroin addiction means that a person has a strong need to keep using heroin even though it causes harm to themselves or others. Heroin addiction is also called opioid use disorder.

Several health problems can develop with heroin use. They can include:

  • Bacterial infections of the blood vessels and heart valves.
  • Liver or kidney disease.
  • Lung problems, such as pneumonia and tuberculosis, from poor health.
  • Hepatitis B and C, HIV, and other diseases, if using shared injection equipment or fluids.

Heroin can be detected in the urine for up to 24 hours and in blood for as long as 48 to 72 hours after use.

If you or someone you know uses heroin, talk to your doctor or pharmacist about a take-home naloxone kit. Naloxone helps reverse the effect of opioids. A kit can help, and can even save your life, if you have taken too much heroin. You can get naloxone without a prescription at most drugstores or through a community Take Home Naloxone program.

Signs of use

Signs that a person is using heroin include:

  • Having supplies for injecting heroin, called an outfit or rig. This may include a spoon or bottle cap to cook the drug, a syringe or needle to inject it, a tourniquet or towel to find a vein, cotton, and matches to heat and dissolve the drug in water.
  • Restlessness, sleepiness, diarrhea, vomiting, chilled feelings, and leg movements. These can happen if the person is physically dependent on the drug and has not had it recently.
  • Personality changes.
  • Unexplained scars on arms or legs or tattoos hiding scars.


Current as of: March 22, 2023

Author: Healthwise Staff
Medical Review:
Patrice Burgess MD - Family Medicine
Adam Husney MD - Family Medicine
Martin J. Gabica MD - Family Medicine
Christine R. Maldonado PhD - Behavioral Health
Kathleen Romito MD - Family Medicine
Michael F. Bierer MD - Internal Medicine, Addiction Medicine