How Long Does Heroin Stay in Your System?

Heroin leaves the blood fast but leaves traces much longer. The drug itself has a half-life of only 30 minutes. Your body converts it rapidly into 6-monoacetylmorphine (6-MAM) and then morphine, both of which drug tests detect. A standard urine test picks up heroin metabolites for 2 to 7 days after the last use. Hair follicle tests extend that window to 90 days. About 22,000 people search for how long heroin stays in their system every month, often because of workplace testing, probation requirements, or treatment-related monitoring.

Heroin Detection Times by Test

Urine: 2 to 7 days. 6-MAM is the definitive marker for heroin (versus other opioids). Standard panels test for morphine and codeine metabolites.
Blood: 5 to 6 hours for heroin. Morphine detectable for up to 12 hours.
Saliva: 1 to 4 hours for heroin. Morphine detectable for 1 to 4 days.
Hair: Up to 90 days. Hair testing is the longest detection window available.

What Happens After You Use Heroin

Heroin is a prodrug. It crosses the blood-brain barrier and converts to 6-MAM within minutes. 6-MAM then converts to morphine. Morphine binds to opioid receptors, producing pain relief, euphoria, and respiratory depression. The entire conversion from heroin to morphine happens within 15 to 30 minutes.

Drug tests rarely detect heroin itself because it converts so quickly. Instead, labs test for 6-MAM (which is unique to heroin) and morphine. The presence of 6-MAM confirms heroin use specifically, as opposed to medical morphine or other opioids.

Why Detection Windows Vary

Frequency of use: Chronic users accumulate metabolites. A person who uses heroin daily for months will test positive longer than a single-use case.
Dose: Higher doses produce more metabolites that take longer to clear.
Route: Injecting heroin delivers the drug faster but does not meaningfully change elimination timelines compared to smoking or snorting.
Metabolism: Liver enzyme activity varies between individuals. Age, genetics, and liver health all affect processing speed.
Body composition: Morphine is partially metabolized through fat tissue. Higher body fat may slightly extend detection.

Urine Testing in Detail

Urine testing is the most common method for heroin detection. Standard immunoassay panels screen for opiates at a 2,000 ng/mL or 300 ng/mL cutoff, depending on the protocol. A positive screen triggers confirmatory testing (GC-MS or LC-MS/MS) that identifies specific metabolites.

For a single use, urine tests typically clear within 2 to 3 days. Moderate use (several times per week) extends detection to 4 to 5 days. Heavy daily use can produce positive results for 7 days or longer.

6-MAM is considered the definitive biomarker for heroin use because no other commonly used drug produces it. Detection of 6-MAM in urine confirms heroin use even when morphine levels could come from legitimate medical sources. However, 6-MAM has a very short detection window of approximately 2 to 8 hours, so late testing may miss it entirely.

Heroin and Fentanyl Contamination

Most heroin sold in the United States now contains fentanyl. A person who tests positive for heroin metabolites may also test positive for fentanyl or its metabolite norfentanyl on expanded panels. Fentanyl has its own detection window (1 to 3 days in urine) and requires a separate assay because it is a synthetic opioid that standard opiate panels do not detect.

Beyond the Test

If you are asking how long heroin stays in your system, the answer matters less than why you are asking. Heroin use disorder is one of the most severe substance use disorders. It carries high overdose risk, devastating health consequences, and profound life disruption. Medication-assisted treatment with buprenorphine or methadone reduces overdose death by more than 50%. Medically supervised detox provides a safe starting point. The test result is temporary. Recovery is permanent.