How long detox takes depends almost entirely on what substance you’re clearing. Alcohol can leave your system in under 24 hours, while cannabis metabolites may linger for weeks or even months. Beyond the substance itself, your body weight, liver health, kidney function, and how heavily you used all shift the timeline. Here’s what to expect for the most common substances and the factors that speed things up or slow them down.
Alcohol: Hours to a Full Day
Your liver processes roughly one standard drink per hour, which works out to about 7 grams of pure alcohol every 60 minutes for someone weighing around 154 pounds (70 kg). That rate isn’t perfectly constant. It shifts slightly depending on how much alcohol is in your blood at a given moment, but one drink per hour is a reliable ballpark. A night of moderate drinking (three to four drinks) typically clears within four to six hours after your last sip. Heavier sessions take proportionally longer.
Total metabolic capacity tops out at roughly 170 to 240 grams per day, so even a very heavy night of drinking is usually processed within 24 hours in terms of blood alcohol reaching zero. Urine tests can pick up alcohol byproducts for an additional 12 to 24 hours beyond that, and specialized tests measuring a metabolite called EtG may detect drinking for up to 72 hours.
Cannabis: Days to Months
THC is one of the slowest substances to leave your body, and the reason is simple: it dissolves into fat. After you smoke or ingest cannabis, THC distributes into fatty tissue throughout your body, then slowly trickles back into your bloodstream over days or weeks. That slow release from fat stores is the bottleneck for elimination.
If you use cannabis occasionally, urine tests typically come back clean within about four days. Chronic, daily users face a very different timeline. Studies of heavy users found THC metabolites detectable in urine anywhere from 3 to 25 days after the last use, with a median of about 7 days using sensitive testing. In some frequent, long-term users, metabolites remained detectable for at least 24 days, and standard screening can sometimes pick them up for a month or more. The more body fat you carry and the longer you’ve been using regularly, the more THC your body has stored and the longer clearance takes.
Opioids: 4 to 20 Days for Acute Detox
Opioid clearance timelines split into two categories based on how fast the drug acts. Short-acting opioids like heroin trigger withdrawal symptoms within 8 to 24 hours of the last dose, and the acute phase lasts 4 to 10 days. Long-acting opioids like methadone start withdrawal later, around 12 to 48 hours after the last dose, and acute symptoms stretch to 10 to 20 days.
During that acute window, expect nausea, vomiting, muscle cramps, insomnia, hot and cold flushes, heavy sweating, and watery eyes and nose. These symptoms peak in intensity during the first few days, then gradually ease. After the acute phase passes, a longer recovery period can follow, lasting up to six months, marked by low mood, reduced energy, and strong cravings. That extended phase doesn’t mean the drug is still in your system. It reflects your brain recalibrating its chemistry after prolonged exposure.
Stimulants: 1 to 5 Days
Stimulants clear relatively quickly compared to cannabis or opioids, but the exact window varies by substance.
- Cocaine itself has an extremely short half-life of less than two hours, but its primary breakdown product stays detectable in urine for one to two days after use.
- Methamphetamine lingers longer, with a half-life of 6 to 17 hours and a urine detection window of one to five days.
- Amphetamine follows a similar pattern: one to five days in urine.
- MDMA (ecstasy) has a half-life of 6 to 10 hours and is typically detectable in urine for one to three days.
The wide ranges reflect individual variation. Someone who used a single dose on one occasion will land at the shorter end. Repeated or heavy use pushes detection toward the longer end.
Benzodiazepines: 1 Day to Over a Month
Benzodiazepines vary dramatically depending on which specific medication is involved. Short-acting versions may clear urine within 24 hours. Intermediate-acting types like alprazolam (Xanax) or lorazepam (Ativan) are typically detectable for one to five days. Long-acting versions like diazepam (Valium) can show up in urine for five to eight days after a single use. Chronic, heavy use of any benzodiazepine can extend detection to 30 days or more, because these drugs accumulate in the body over time.
What Makes Your Body Faster or Slower
The timelines above are averages. Several factors can shift your personal clearance window significantly.
Body fat plays a major role for any fat-soluble substance, including cannabis, benzodiazepines, and many other drugs. In studies comparing people with higher body fat to lean controls, the half-life of diazepam was five times longer and the drug spread into a volume of tissue seven times larger. The same pattern applies to other fat-soluble compounds: more body fat means more storage capacity and a slower release back into the bloodstream.
Liver health is central to the process. Your liver breaks down most substances in two stages. First, enzymes chemically alter the drug to make it more reactive. Then, a second set of enzymes attaches the altered drug to a water-soluble molecule so your kidneys can flush it out. Any liver damage, whether from alcohol, hepatitis, fatty liver disease, or other causes, slows both stages and extends clearance times.
Kidney function determines how quickly those water-soluble byproducts actually leave your body through urine. Healthy kidneys filter and actively pump drug metabolites out of the blood using specialized transport channels. When kidney function declines, waste products build up and can even interfere with the transporters responsible for clearing drugs, creating a compounding slowdown. Staying well-hydrated supports kidney filtration but won’t dramatically speed up clearance on its own.
Age also matters, though less predictably. Older adults tend to have lower liver enzyme activity, reduced kidney filtration, and changes in body composition that collectively slow drug metabolism.
Acute Detox vs. Full Recovery
There’s an important distinction between clearing a substance from your bloodstream and your brain fully recovering from regular use. Physical detox, meaning the drug and its metabolites reaching undetectable levels, follows the timelines above. Neurological recovery is a separate, longer process.
Post-acute withdrawal is best studied in alcohol. After the initial withdrawal phase ends, many people experience a period of low mood, anxiety, difficulty feeling pleasure, poor sleep, and cognitive fog. Anhedonia, the inability to enjoy things that normally feel good, tends to be most intense during the first 30 days of abstinence. Cravings peak in the first three weeks. Sleep problems can persist for up to six months. Mood and anxiety symptoms generally improve over the first three to four months, and cognitive function keeps recovering for months to a year. Some subtle improvements in brain function continue for years.
Recovery appears fastest during the first two to three weeks of abstinence, with continued gains that research has tracked for nearly a decade. The key takeaway is that feeling off for weeks or months after quitting doesn’t mean something is wrong. It reflects the normal pace of your brain restoring its chemical balance after sustained substance exposure.