Heroin itself leaves your bloodstream within minutes, but the markers a drug test looks for can show up for roughly 1 to 3 days in urine, up to about 6 hours in blood, around a day in saliva, and up to about 90 days in hair.

The question usually comes with a lot of worry attached. Maybe there’s a drug test coming up, or you’re watching a family member and trying to understand what’s happening in their body. Either way, the real answer is that it depends on the person, the test, and how heroin breaks down once it’s inside you.

This article is for general education and is not a substitute for a medical assessment. If heroin use is part of your life or your family’s, our heroin addiction treatment team can help you understand your options.

What is heroin?

Heroin, known medically as diacetylmorphine, is an opioid made from morphine, which comes from the opium poppy. People inject, smoke, or snort it. Once it reaches the brain, it binds to mu-opioid receptors and produces a rush of euphoria along with sedation and slowed breathing.

Heroin is a prodrug, which is a useful thing to understand when you’re asking how long it stays around. The drug is only active for a very short time before the body converts it into other compounds that do most of the work. That conversion is exactly why heroin is so fast-acting and why it barely registers on a standard test as heroin itself. For more on how heroin fits into the wider opioid family, see our guide to the types of opioids and their addiction risks.

How long does heroin stay in your system?

Heroin has a very short half-life. Studies of the drug put its elimination half-life at only a few minutes, and one Johns Hopkins study of smoked heroin measured it at about 3 minutes, with its first active metabolite close behind. According to StatPearls from the National Library of Medicine, heroin is rapidly metabolized to 6-monoacetylmorphine (6-MAM) and then to morphine, and it’s these metabolites, not heroin, that hang around long enough to be measured.

So when people ask how long heroin stays in the system, what they’re really measuring is how long morphine and 6-MAM stay detectable. Morphine takes longer to clear than heroin, and 6-MAM sits in the middle. One helpful detail: 6-MAM is unique to heroin, so if a lab finds it, that result points specifically to heroin rather than to prescription morphine or codeine. The catch is that 6-MAM clears quickly, often within several hours.

Heroin detection windows by test type

Different tests look for heroin’s metabolites over different windows. The ranges below are typical estimates. Your own numbers can fall outside them depending on your body and how much you used.

Type of test	Approximate detection window
Urine	About 1 to 3 days
Blood	Up to about 6 hours
Saliva	About 1 hour to 1 day
Hair	Up to about 90 days

Urine testing is the most common method and picks up the morphine metabolite for a day or three after use. Blood has the shortest reach, since heroin and 6-MAM disappear so fast. Hair has the longest window by far, because traces get locked into strands as they grow, though it’s poor at catching very recent use.

What affects how long heroin stays in your system?

Two people can use the same amount of heroin and clear it at different speeds. A few things explain that:

• How much and how often you use. Larger and more frequent doses take longer to clear, and metabolites can build up with heavy, repeated use.
• Your metabolism and body composition. Age, liver and kidney function, body fat, and hydration all shift how quickly the drug is processed and eliminated.
• The type of test. As the table shows, a hair test and a blood test are measuring very different windows for the same drug.
• Other substances. Alcohol and other drugs can affect how the liver handles opioids, and heroin is often mixed with fentanyl, which has its own detection pattern. You can read more in our guide to how long fentanyl stays in your system.
• Purity and what it’s cut with. Street heroin varies widely in strength and additives, so the actual dose someone takes is rarely clear.

Can you flush heroin out of your system faster?

There’s no reliable way to speed this up. Drinking water, exercising, or taking detox products won’t change how fast your liver metabolizes heroin. Time is the only thing that clears the metabolites.

There’s a more important safety point here. If you’ve been using heroin regularly and then stop, your tolerance drops quickly. Going back to a previous dose after even a short break is one of the most dangerous moments for an overdose, a risk made worse by fentanyl in the drug supply. If you’re worried about overdose, please read our guide on opioid overdose and its dangers and keep naloxone on hand.

What does heroin withdrawal feel like?

Once heroin and its metabolites start leaving the body, someone who is dependent will usually begin to feel withdrawal. Early symptoms such as anxiety, sweating, muscle aches, a runny nose, and cravings often start within about 8 to 24 hours of the last dose. They tend to peak around days two and three, with nausea, vomiting, diarrhea, stomach cramps, chills, and trouble sleeping, then ease over roughly a week, though low mood and cravings can linger longer.

Heroin withdrawal is rarely life-threatening on its own, but it’s hard to get through alone, and the drop in tolerance it creates raises overdose risk if someone relapses. Medical support makes it safer and far more bearable. Our overview of opioid withdrawal symptoms and stages walks through what to expect in more detail.

Getting OHIP-covered heroin treatment in Ontario

Thrive Medical is a Rapid Access Addiction Medicine (RAAM) clinic serving North York and the wider Greater Toronto Area, with virtual appointments available across Ontario. You don’t need a referral or an appointment far in advance to get started, and assessment and treatment are covered by OHIP for eligible patients.

For opioid use, care often includes medication-assisted treatment with buprenorphine (Suboxone) or methadone, which eases withdrawal, reduces cravings, and lowers overdose risk, alongside counselling and ongoing support. If you’re new to this, our explainer on what RAAM clinics are and how they work is a good place to start, and you can see the full list of OHIP-covered addiction treatments we offer. When you’re ready, you can reach out to our team to book a confidential assessment. You can also find free, confidential support anywhere in the country through Health Canada’s get help with substance use service.

Frequently Asked Questions

How long does heroin stay in your urine?

A standard urine test usually detects heroin’s morphine metabolite for about 1 to 3 days after the last use. Heavy or repeated use can push that toward the longer end. The heroin-specific marker, 6-MAM, clears much faster, often within several hours, so it’s only found soon after use.

Can a drug test tell heroin apart from prescription opioids?

A basic opiate screen can’t always separate heroin from morphine or codeine, since heroin breaks down into morphine. To confirm heroin specifically, labs look for 6-monoacetylmorphine (6-MAM), a metabolite unique to heroin. Because 6-MAM disappears quickly, it’s only detectable for a short window after use.

How long does heroin stay in your blood?

Blood tests have the shortest detection window for heroin, generally up to about 6 hours. Heroin itself is broken down within minutes, and its metabolites clear from the blood fast. Blood testing is used less often for routine screening and more in medical or forensic settings.

Does drinking water flush heroin out faster?

Not in any meaningful way. Water, exercise, and over-the-counter detox products don’t change how quickly your liver metabolizes heroin. Only time clears the metabolites. Trying to “flush” your system can also be risky if it delays getting real help for opioid use.

How long after heroin does withdrawal start?

For someone who is dependent, withdrawal usually begins about 8 to 24 hours after the last dose, peaks around the second or third day, and eases over roughly a week. Cravings and low mood can last longer. Medical support makes withdrawal safer and more comfortable.

Is it safe to detox from heroin at home?

Heroin withdrawal is rarely fatal on its own, but it’s very difficult alone, and the drop in tolerance raises overdose risk if you relapse. A medical team can ease symptoms and start medication that lowers cravings. If you’re considering it, talk to a provider first about the safest path for your situation.

Sources

• StatPearls / National Library of Medicine, Heroin Toxicity
• National Library of Medicine, Urine Drug Testing detection windows
• Jenkins et al., Johns Hopkins University, Pharmacokinetics of smoked heroin
• Substance Abuse and Mental Health Services Administration (SAMHSA)
• Centers for Disease Control and Prevention (CDC)
• Health Canada

Last reviewed: August 2026. This article is for general educational purposes and does not replace medical advice. Talk to a licensed healthcare provider about your specific situation. If you think someone is overdosing on heroin or another opioid, give naloxone if available and call 911 right away.