Heroin is the drug most people picture when they think of addiction, and increasingly it is not what is actually in the bag. Across most of the United States, what is sold as heroin now contains fentanyl, sometimes exclusively. Anyone using street opioids should assume fentanyl exposure, carry naloxone, and avoid using alone.
Quick reference
| Drug class | Semi-synthetic opioid (diacetylmorphine) |
|---|---|
| DEA schedule | Schedule I |
| Routes | Injected, smoked, snorted |
| Withdrawal onset and peak | 6 to 12 hours after the last dose; peaks at 24 to 72 hours |
| Is withdrawal dangerous? | Rarely fatal by itself in a healthy adult. The real dangers are dehydration and overdose after tolerance falls |
| Detection window | Metabolites typically detectable in urine for two to three days; hair testing detects months of use |
| Key medical risks | Endocarditis, hepatitis C, HIV, abscesses, osteomyelitis, sepsis |
| Treatment medications | Buprenorphine, methadone, extended release naltrexone |
What heroin does
Heroin binds mu-opioid receptors, producing a large dopamine release in the brain reward pathway along with pain relief, sedation and slowed breathing. Because it crosses into the brain faster than morphine, the onset is abrupt and intense.
Users describe an initial rush followed by hours of drowsy, warm detachment, with clouded thinking and heavy limbs. Nausea, intense itching and constipation are typical. Tolerance escalates quickly, so within weeks the dose that once produced euphoria only prevents withdrawal.
That last point reframes the whole condition and is worth stating plainly: most people in long term heroin use are not chasing a high, they are managing sickness. Families who understand this usually interpret the behavior they are seeing very differently.
Signs of heroin use
Physical: constricted pupils, nodding off mid sentence, slowed and slurred speech, persistent scratching, flushed skin, weight loss, constipation, deteriorating dental health, needle marks or scarred veins, abscesses.
Behavioral: long sleeves in warm weather, new secrecy, unexplained absences, missing money or valuables, abandoned friendships, sudden indifference to work and appearance, hostility when questioned.
Paraphernalia: small wax paper folds or balloons, burnt spoons or foil, cotton, syringes, tourniquets, glass stems.
Medical risks beyond overdose
- Endocarditis, infection of a heart valve. Life threatening, and often requiring weeks of intravenous antibiotics or valve surgery. It is one of the most common reasons people who inject drugs are hospitalized.
- Hepatitis C and HIV. Both matter and both are manageable. Hepatitis C is now curable with 8 to 12 weeks of oral medication, and HIV is controlled with modern antiretroviral therapy. Testing is worth doing.
- Skin and soft tissue infections, abscesses, cellulitis, chronic wounds, and the severe ulceration associated with xylazine adulterated supply.
- Aspiration pneumonia after nodding off, and pulmonary edema.
- Hormonal effects, including disrupted menstrual cycles, suppressed testosterone and infertility.
Syringe services programs reduce HIV and hepatitis C transmission, and research consistently finds that people who use them are more likely to enter treatment, not less.
Withdrawal timeline
- 6 to 12 hours: anxiety, restlessness, yawning, runny nose and eyes, sweating, craving.
- 1 to 3 days, the peak: muscle and bone pain, restless legs, chills and goosebumps alternating with sweating, dilated pupils, cramping, vomiting, diarrhea, insomnia, severe craving.
- 4 to 10 days: physical symptoms fade while fatigue and low mood persist.
- Weeks to months: disrupted sleep, blunted pleasure, low motivation and intermittent craving. Most relapses happen in this phase rather than the first week.
Where fentanyl is involved, which is now the default assumption, expect a faster onset, a longer tail, and a buprenorphine start that requires a specific protocol.
Treatment
Medication for opioid use disorder is the foundation and roughly halves mortality. Buprenorphine can be prescribed by any clinician with a standard DEA registration since the X-waiver requirement was eliminated. Methadone is dispensed through licensed opioid treatment programs and often suits people with very high tolerance. Extended release naltrexone requires 7 to 10 days fully opioid free before the first injection.
Around the medication: cognitive behavioral therapy and relapse prevention, contingency management, treatment of co-occurring depression, PTSD or anxiety, medical care for infections and hepatitis C, and practical help with housing and employment. Family involvement measurably improves outcomes.
Common questions
Is heroin still around, or is it all fentanyl now?
Both. Heroin has not disappeared, but in much of the country the supply is dominated by fentanyl, sometimes with no heroin present. Assume fentanyl exposure and act accordingly.
Can someone recover without medication?
Some people do, and the odds are considerably worse. Medication for opioid use disorder has the strongest evidence base in addiction medicine. If someone refuses it, treat them with what they will accept rather than making medication a condition of any help at all.
Does a standard drug test detect fentanyl?
Often not. Many standard opioid panels do not include fentanyl, which requires a separate test. This matters if you are trying to understand what someone is actually using.
What should I do if my adult child is using heroin?
Learn overdose response and keep naloxone in the house. Stay in contact while being clear about what happens in your home. Get your own support through Al-Anon, Nar-Anon or SMART Recovery Family and Friends. Have a treatment plan researched in advance, because windows of willingness are short.
Sources
- National Institute on Drug Abuse, heroin research report
- CDC, overdose prevention data and naloxone guidance
- SAMHSA, Medications for Opioid Use Disorder (TIP 63)
- CDC, hepatitis C treatment and cure rates with direct-acting antivirals
Need help now? In an emergency call 911. If you are in crisis or thinking about suicide, call or text 988 (Suicide and Crisis Lifeline; veterans press 1). For free, confidential treatment referrals 24 hours a day, call the SAMHSA National Helpline at 1-800-662-4357. You can also search licensed programs at FindTreatment.gov, or use our rehab directory and state listings.
Addiction Now publishes health journalism and reference material. This page is not medical advice, a diagnosis, or a treatment plan. Do not stop a prescribed medication without talking to a clinician. Withdrawal from alcohol, benzodiazepines and barbiturates can cause seizures and can be fatal without medical supervision.
Related reference pages
Reviewed and updated July 30, 2026 by the Addiction Now editorial team. Figures cited come from the CDC, NIDA, SAMHSA and the FDA.
