Heroin is used in three primary ways: injecting it into a vein, smoking it, and snorting it as a powder. Each method delivers the drug to the brain at a different speed, but all carry serious risks of dependence, overdose, and long-term organ damage. The route someone chooses often depends on the form of heroin available, personal tolerance, and how quickly they want to feel the effects.
Three Routes of Use
Injection is the method most people associate with heroin. The powder or tar form is dissolved in water, heated in a small spoon or metal “cooker,” drawn through a filter into a syringe, and injected into a vein. When injected intravenously, the initial rush hits in about seven to eight seconds and lasts from 45 seconds to a few minutes. Some users inject under the skin or into muscle tissue instead, which produces a slower onset of around five to eight minutes.
Smoking involves heating heroin on a piece of aluminum foil and inhaling the vapor through a tube, pipe, or hollowed-out pen. This method is sometimes called “chasing the dragon.” The onset is fast, though not quite as immediate as injection, because the drug absorbs through the lungs rather than entering the bloodstream directly.
Snorting means chopping the powder form into fine lines on a flat surface (often a mirror or phone screen) and inhaling it through the nose using a straw, rolled paper, or similar tube. Razor blades or credit cards are commonly used to break up and arrange the powder. Absorption through the nasal lining is slower than both injection and smoking, so the effects build more gradually. Regardless of how heroin enters the body, its effects generally last three to five hours depending on the dose.
What Happens in the Body
Once heroin reaches the brain, it converts into morphine and binds to opioid receptors. These receptors regulate pain, pleasure, and breathing. The initial “rush” is a surge of intense pleasure, followed by a warm flushing of the skin, dry mouth, and a heavy feeling in the arms and legs. Severe itching, nausea, and vomiting are common. After these first effects wear off, users typically become drowsy for several hours as their breathing slows down.
This slowed breathing is what makes heroin so dangerous. During an overdose, breathing can drop so low that the brain doesn’t receive enough oxygen, which can cause brain damage, coma, or death within minutes.
How Tolerance and Dependence Build
Repeated use leads to tolerance, meaning the same dose stops producing the same effect. Users need progressively larger amounts to feel the original high. Over time, the body becomes physically dependent on the drug. If someone who is dependent stops using heroin, withdrawal symptoms begin within 6 to 12 hours of the last dose and typically last about five days. These include restlessness, muscle and bone pain, diarrhea, vomiting, and cold flashes with goose bumps.
Beyond physical dependence, repeated use often leads to heroin use disorder, a chronic brain condition where someone continues using despite clear harm to their health, relationships, and daily life. This distinction matters: physical dependence is the body adapting to the drug’s presence, while addiction involves compulsive use that the person struggles to control even when they want to stop.
Health Damage by Route
Each method of use creates its own pattern of damage on top of the systemic harm heroin causes.
- Injection carries the highest risk of infectious disease. Sharing needles or syringes can transmit HIV, hepatitis B, hepatitis C, and other blood-borne infections. Chronic injection leads to scarred or collapsed veins, abscesses, and bacterial infections of the blood vessels and heart valves (endocarditis).
- Snorting damages the mucosal tissue lining the nose and can eventually perforate the nasal septum, the wall of cartilage separating the nasal passages.
- Smoking contributes to lung complications including pneumonia and tuberculosis, compounded by heroin’s effect of depressing respiration.
Long-term use by any route can cause liver, kidney, and lung disease, as well as mental health disorders. Street heroin also contains additives that don’t dissolve fully in the bloodstream. These particles can clog small blood vessels leading to the lungs, liver, kidneys, or brain, killing small patches of cells in those organs. Immune reactions to contaminants can also trigger arthritis and other inflammatory conditions.
What’s Actually in the Supply
One of the most dangerous aspects of current heroin use is that the drug is rarely pure. Heroin is frequently mixed with fentanyl, a synthetic opioid that is far more potent, and increasingly with xylazine, a veterinary sedative that has no approved use in humans.
Xylazine is cheap, which makes it attractive to drug traffickers looking to stretch their supply. It produces effects that feel similar to opioids but last longer than fentanyl alone. The problem: xylazine is not an opioid, so naloxone (the standard overdose reversal drug) does not counteract it. When heroin or fentanyl is mixed with xylazine, the combined depression of breathing becomes more dangerous, and standard overdose rescue is less effective. Naloxone can still address the opioid component and may be enough to prevent death, but it won’t reverse xylazine’s effects.
Users who inject xylazine-laced drugs develop severe soft tissue wounds that can progress to dead, blackened skin and in some cases require amputation. Xylazine also creates its own physical dependence, with withdrawal symptoms that some users describe as more severe than heroin or methadone withdrawal, including sharp chest pain and seizures.
Signs That Someone May Be Using
The physical signs of heroin use vary depending on the route, but certain indicators are consistent. During active intoxication, a person will have constricted “pinpoint” pupils, extreme drowsiness (often nodding off mid-conversation), slowed breathing, and flushed skin. Nausea, vomiting, and intense scratching are common.
Paraphernalia is often the most concrete evidence. Items associated with injection include small spoons with burn marks, syringes, tourniquets, cotton filters, and alcohol pads. Smoking-related items include aluminum foil with burn trails, glass or metal pipes, and lighters or small torches. Snorting may leave behind razor blades, cut straws, rolled paper, and powder residue on flat surfaces.
Over the longer term, people who inject may have visible track marks (small puncture wounds, often along the inner arm), wear long sleeves in warm weather to hide them, and develop abscesses or skin infections at injection sites. Weight loss, withdrawal from social activities, and rapid mood shifts between euphoria and lethargy are behavioral patterns that cross all routes of use.