Understanding drug metabolism
How Long Do Drugs Stay in Your System?
The moment drugs enter your body, your cells work to get rid of them — your stomach, kidneys, liver, and colon isolate drug molecules and bundle them up for excretion. How long that takes varies by substance, and by person.
About this guide
Drug half-life guide
Scientists measure a drug's active life by metabolism: the point at which half of a dose has been removed is the drug's half-life. Your timeline might differ from someone who took the same drug — metabolism varies with age, body composition, genetics, weight, and prior drug use.
Published half-lives are approximations based on studies of hundreds or thousands of people, so your experience may differ — but the timeframes are useful for understanding how a substance changes your body and brain. For substances where half-life does not apply, including alcohol, researchers instead measure when blood levels peak — the point of strongest intoxication, after which sobriety gradually returns.
Ambrosia's detox and treatment programs in West Palm Beach and Singer Island help people stop worrying about timeframes altogether — with medical supervision through withdrawal and therapy for what comes after.
Classic drugs
Some substances have been around for decades and studied over and over, so scientists know a lot about how they move through the body:
Alcohol
The liver processes ethanol at about 15 grams per hour — roughly one alcoholic beverage. Drink faster than that, and your body needs longer to recover.
Marijuana
Blood levels peak within about 10 minutes of smoking; ingesting the drug takes about an hour to reach maximum blood levels.
Cocaine
Researchers report a roughly one-hour half-life, varying with whether the drug is smoked or sniffed.
Heroin
Heroin's half-life is about 3 minutes, but the substances it transforms into can persist with a nearly 20-minute half-life.
Prescription drugs
Pharmaceuticals are extensively documented before they reach the market, so their timeframes are well understood:
Opioid painkillers
Structurally similar to heroin and sharing the same receptors, most painkillers have a half-life of about 4 hours.
Suboxone and Subutex
The buprenorphine in each dose has a roughly 37-hour half-life — one of the longest-lasting drugs available.
Adderall
A half-life of about 11 hours in studies — though those were conducted on people who had not eaten in a while, and food can change metabolism.
Benzodiazepines
Each anxiety medication in this class works a little differently, with half-lives ranging from 5 to 24 hours.
Newer street drugs
Novel substances are harder to characterize precisely because they are so new — and because clandestine manufacturing varies:
Methamphetamine
A half-life of about 10 hours, though it can vary considerably depending on how the drug was made.
Kratom
A natural plant, often altered in labs to increase potency, with a half-life of about 16 hours.
Synthetic marijuana
Products like K2 or Spice are typically felt for about 30 to 120 minutes.
What about drug tests?
Some people study these numbers hoping to game an employment or law enforcement drug test — to know when their urine or blood will be “clean” so they can keep using without getting caught.
If that is why you are here, know this: drug tests can pick up traces of use for weeks or even months, depending on the method used, and getting caught can cost you opportunities, your freedom, or both. Treatment offers a different way out — a life where you are not living in fear of the next test, and can simply enjoy life again without drugs.
Ready to talk with admissions?
Admissions is available 24/7 to answer questions about mental health and substance use treatment options.