How Long Does Heroin Stay in Your System? What Each Test Finds, for How Long, and Why Fentanyl Changes the Answer

Heroin itself is gone from the body within minutes. What a drug test finds is what the body turns it into, and each of those markers has its own clock: hours for the one that proves heroin specifically, a few days for morphine in urine, and months in hair. This page gives the window for each kind of test from the federal testing rules and laboratory references, explains why a heroin test and a fentanyl test are not the same thing, and ends with the question most people are really asking, which is when withdrawal starts. “Dope” here means heroin, the sense the laboratory references use; if you mean methamphetamine, the meth page has its own timeline.

Heroin shows in urine as morphine for one to three days after use, and as 6-acetylmorphine for less than a day. Urine is the specimen almost every employer, court and clinic uses.

The federal workplace rules, which most private testing copies, set two cutoffs for the opiate panel. A specimen is positive for morphine at 2,000 nanograms per milliliter, and positive for 6-AM at 10 nanograms per milliliter. The morphine cutoff is deliberately high because codeine, prescribed morphine and even poppy seeds all produce morphine in urine; the 2001 study above notes that this is exactly why the federal program raised the cutoff and required 6-AM confirmation. A morphine result alone says an opiate was taken. A 6-AM result says it was heroin, and because 6-AM clears within hours, a positive 6-AM test means use was recent.

In practice a urine test taken the morning after use is positive. A test two days later usually is for a regular user and may not be for an occasional one. A test four or five days later is usually negative for morphine unless use was heavy and daily.

Source: Mandatory Guidelines for Federal Workplace Drug Testing Programs, Department of Health and Human Services, Federal Register, January 23, 2017, effective October 1, 2017.

Heroin shows up in a hair test for about 90 days on the standard inch-and-a-half sample. It does not show for the first five to seven days, because the drug has to grow out of the scalp first.

Hair records drug use rather than measuring it. Metabolites travel through the bloodstream to the hair follicle and are built into the shaft as it forms. The Department of Health and Human Services’ proposed federal hair rules put the average growth rate at about one centimeter a month and note that drug analytes do not appear in hair for five to seven days after use, which is why hair is unsuitable for detecting recent use and is reserved for pre-employment and random testing. The federal proposal tests a half-inch to one inch of hair, representing roughly 30 to 60 days; commercial labs usually cut one and a half inches, which at that growth rate is about three months.

The hair panel looks for 6-AM as well as morphine, at 200 picograms per milligram, so a hair test can distinguish heroin from prescribed opiates in a way a morphine-only urine result cannot.

Source: Mandatory Guidelines for Federal Workplace Drug Testing Programs using Hair, proposed, Department of Health and Human Services, Federal Register, September 10, 2020.

Fentanyl does not show up on a standard opiate screen at all. The opiate panel detects morphine and its relatives; fentanyl is a synthetic opioid with different metabolites and has to be tested for separately.

This matters because most of what is sold as heroin now contains fentanyl, and some of it contains no heroin. A guide for clinicians in Federal Practitioner states it plainly: synthetic opioids such as fentanyl, methadone or meperidine are not detected by the opiate immunoassay and need to be ordered separately. The real-world size of the gap showed up in a Baltimore emergency department surveillance study published by the CDC. Of patients tested in 2019, 83 percent were positive for fentanyl on a specific fentanyl test, and the hospital’s ordinary opiate screen was negative for 55 percent of those fentanyl-positive specimens.

So someone who has been using “dope” that is mostly fentanyl can pass an opiate screen and fail a fentanyl test, or pass both if only the opiate panel was run. When fentanyl is tested for, ARUP’s reference gives it and its metabolite norfentanyl a urine window of one to three days, similar to morphine. The opioid detox page covers the medication approach when fentanyl is what is really in the supply.

Source: A Practical Guide to Urine Drug Monitoring, Raouf, Bettinger and Fudin, Federal Practitioner, 2018; Notes from the Field: High Prevalence of Fentanyl Detected by the Maryland Emergency Department Drug Surveillance System, Baltimore, Maryland, 2019, Dezman et al., MMWR, June 12, 2020.

Detection windows matter in detox because the admission drug test, not the person’s account, tells the physician what is actually in the body. A fentanyl result changes the buprenorphine plan, and Briarwood tests for it.

Buprenorphine, the medication in Suboxone, has to be started after withdrawal has begun, and when fentanyl is on board it is started in much smaller steps to avoid precipitated withdrawal. The Suboxone for heroin detox page explains the timing. Nobody at admission is trying to catch anyone out; the test exists so the first dose is the right one.

Medically supervised heroin detox at Briarwood runs in Austin and Houston, with nursing around the clock, comfort medication from the first hours, and the step after detox arranged before discharge, because the days when tolerance has fallen are the dangerous ones. Cost and insurance covers what a stay costs with and without coverage. Admissions is answered at every hour, and if the question is whether a test on Friday will still be positive on Monday, the better question to ask is what the next three days are going to be like without help.