Withdrawal symptoms can start anywhere from a few hours to several days after your last dose, depending on the substance. The single biggest factor is how quickly the drug leaves your body. Fast-acting substances like heroin or nicotine trigger withdrawal within hours, while slower-acting ones like methadone may not produce symptoms for days.
Why Onset Times Vary So Much
Every substance has a “half-life,” which is the time it takes for your body to clear half of the drug from your system. Drugs with short half-lives drop out of your bloodstream quickly, and your brain notices the absence fast. That means withdrawal hits sooner and often feels more intense, though it typically resolves faster too. Drugs with long half-lives taper off gradually, so withdrawal creeps in more slowly but can stretch out over weeks.
Your individual biology also shifts the timeline. Body fat matters because many substances get stored in fat cells, which means they take longer to fully clear. Older adults tend to metabolize drugs more slowly than younger people. Liver and kidney health, genetics, overall nutrition, and how much of the substance you were using all play a role. Two people stopping the same drug on the same day can have noticeably different experiences.
Alcohol: 6 to 24 Hours
Alcohol withdrawal typically begins within 6 to 24 hours after your last drink. The earliest symptoms are usually tremors (shaking hands), anxiety, nausea, and sweating. Tremors specifically tend to start within 5 to 10 hours and peak at 24 to 48 hours.
The timeline escalates from there. Seizures can occur 6 to 48 hours after the last drink, with the highest risk falling in the 24 to 48 hour window. Delirium tremens, the most dangerous form of alcohol withdrawal, commonly begins two to three days after the last drink but can sometimes be delayed by more than a week. This unpredictable delay is one reason alcohol withdrawal is considered medically serious, particularly for people with a long history of heavy drinking.
Opioids: 6 Hours to 3 Days
The onset depends heavily on which opioid you were using. Short-acting opioids like heroin and oxycodone produce withdrawal symptoms within 6 to 12 hours of the last dose. You’ll typically feel muscle aches, restlessness, anxiety, and sweating first, followed by more intense symptoms like nausea, vomiting, and diarrhea over the next day or two.
Long-acting opioids like methadone work differently. Because they’re released slowly in the body, withdrawal symptoms don’t usually appear until 1 to 3 days after the last dose. The symptoms are similar but tend to build more gradually and last longer. This extended timeline sometimes catches people off guard because they feel fine for the first day or two and assume they’re in the clear.
Nicotine: Hours, Peaking at Day 2 or 3
Nicotine withdrawal begins quickly. Cravings, irritability, and difficulty concentrating can show up within just a few hours of your last cigarette. These symptoms are most intense on the second or third day of being nicotine-free. After that peak, the physical symptoms gradually ease over the following weeks, though cravings can linger much longer.
Caffeine: Within 12 Hours
If you’ve ever skipped your morning coffee and had a headache by afternoon, you’ve experienced caffeine withdrawal. Symptoms typically start within 12 hours of your last cup. The headache is usually the most noticeable symptom, and it tends to be worst between 20 and 51 hours after your last dose. Fatigue, irritability, and trouble concentrating are common alongside it. Caffeine withdrawal is uncomfortable but not dangerous, and it generally resolves within a week.
Cannabis: 24 to 48 Hours
Cannabis withdrawal is slower to develop than most substances because THC is fat-soluble, meaning it gets stored in your body’s fat cells and releases gradually. Symptoms usually begin within 24 to 48 hours of stopping heavy, long-term use. Irritability, sleep problems, decreased appetite, and cravings are the most common complaints. Severity typically peaks around day three. Not everyone who uses cannabis will experience withdrawal, but daily or near-daily users are much more likely to notice it.
Antidepressants: 2 to 4 Days
Stopping antidepressants (particularly SSRIs and SNRIs) can produce what’s called discontinuation syndrome. Symptoms typically begin within two to four days of stopping the medication. Common experiences include dizziness, nausea, “brain zaps” (brief electrical-shock sensations in the head), flu-like feelings, and mood changes. This is one reason antidepressants are usually tapered gradually rather than stopped abruptly. Discontinuation syndrome is distinct from a relapse of depression, though the two can sometimes overlap and be hard to tell apart in the moment.
Quick Reference by Substance
- Alcohol: 6 to 24 hours
- Heroin/short-acting opioids: 6 to 12 hours
- Methadone/long-acting opioids: 1 to 3 days
- Nicotine: within hours, peaking at day 2 to 3
- Caffeine: within 12 hours
- Cannabis: 24 to 48 hours
- Antidepressants: 2 to 4 days
These windows assume you stop completely. Reducing your dose rather than quitting outright will generally delay the onset and soften the intensity of symptoms. The timelines also represent typical ranges, not hard cutoffs. Your personal experience will depend on how long you used the substance, how much you were taking, and the biological factors unique to your body.