Detox timelines by substance: the first three to ten days.
Withdrawal from alcohol, benzodiazepines, opioids, and stimulants follows different clocks and carries different dangers. This overview lays the timelines side by side, explains which ones make medical supervision a necessity rather than a comfort, and points you to the detailed guides for each.
Authored by the MLJ Clinical Team. Reviewed under board-certified psychiatric oversight. Last updated September 2026.
Key Takeaways- Alcohol and benzodiazepine withdrawal can cause seizures and, in severe cases, death; these two always warrant medical supervision when dependence is present.
- Opioid and fentanyl withdrawal is rarely life-threatening in itself, but it is intensely uncomfortable and the loss of tolerance afterward makes overdose the real danger.
- Stimulant withdrawal is mostly psychological, marked by a depressive crash that can include suicidal thinking, and is safest with psychiatric monitoring.
- Most acute withdrawal resolves in three to ten days, but sleep, mood, and craving continue to shift for weeks; detox is the beginning of treatment, not the whole of it.
- When more than one substance is involved, the timelines overlap and the safest assumption is the most dangerous one.
How to read these timelines.
Every withdrawal timeline on this page describes a typical course. Yours will differ. How long you have been using, how much, how often, your age, your liver and kidney function, what else you take, and whether you have been through withdrawal before all move the numbers. A person who has had one alcohol withdrawal seizure is more likely to have another; a person on a long-acting benzodiazepine will feel symptoms later than someone on a short-acting one. Treat the ranges below as a map, not a schedule.
Two questions organize everything else. First, can this withdrawal hurt you physically? For alcohol and benzodiazepines, the answer is yes. For opioids and stimulants, the direct physical risk is lower, but the indirect risks, overdose after tolerance drops and suicidal thinking during a crash, are serious. Second, how long until the acute phase passes? For most substances, three to ten days. Protracted symptoms, particularly sleep disturbance, low mood, and craving, can persist for weeks and are the reason detox flows directly into residential care at MLJ rather than ending at the door.
Alcohol: the timeline that can turn dangerous late.
Alcohol withdrawal begins early and can escalate for days. Mild symptoms, including tremor, sweating, anxiety, nausea, and a racing heart, often appear within six to twelve hours of the last drink, sometimes before the blood alcohol level has reached zero. Hallucinations, usually visual or tactile, can appear between twelve and twenty-four hours. Withdrawal seizures cluster in the twenty-four to forty-eight-hour window. Delirium tremens, the most dangerous complication, typically begins forty-eight to seventy-two hours in and can last several days; it involves severe confusion, autonomic instability, and, without treatment, a meaningful risk of death.
The clinical trap is that many people feel somewhat better on day two and conclude the worst is over. It may not be. This late escalation is why the National Institute on Alcohol Abuse and Alcoholism and every major clinical guideline recommend medical evaluation for anyone with significant daily drinking who wants to stop (NIAAA Core Resource on Alcohol). Symptom-triggered benzodiazepine or phenobarbital protocols, nursing checks on a fixed cadence, and thiamine to prevent Wernicke's encephalopathy are standard. Acute withdrawal usually resolves within five to seven days; sleep and anxiety take longer. Our detailed alcohol withdrawal timeline walks through each stage hour by hour.
Benzodiazepines: the timeline that cannot be rushed.
Benzodiazepines act on the same GABA receptors alcohol does, and the withdrawal shares its dangers: seizures, severe anxiety, perceptual disturbance, and in rare cases delirium. What differs is the clock. Short-acting agents such as alprazolam produce symptoms within a day of the last dose. Long-acting agents such as diazepam or clonazepam may not produce noticeable withdrawal for several days, which can lull a person into thinking they have stopped without consequence.
Benzodiazepine dependence is the one situation on this page where "detox" does not mean a week. The standard of care is a gradual taper, often converting to a long-acting agent and reducing the dose in steps over weeks or months depending on the starting dose and duration of use. Abrupt discontinuation is dangerous enough that the FDA's boxed warning for the entire drug class names it specifically (FDA, 2020). At MLJ, the first phase of a taper happens under nursing observation in residential; the remainder continues with the same physician as the client steps down through PHP and IOP. Our guide to benzodiazepine tapering explains how the schedule is built.
Opioids and fentanyl: miserable, and dangerous for a different reason.
Opioid withdrawal is often described as the worst flu of your life, and that is roughly accurate: muscle aches, sweating and chills, yawning, dilated pupils, nausea, vomiting, diarrhea, insomnia, and a restless, crawling anxiety. For short-acting opioids such as heroin or oxycodone, symptoms begin eight to twelve hours after the last dose, peak around forty-eight to seventy-two hours, and largely resolve within five to seven days. For long-acting opioids like methadone, onset is delayed to twenty-four to forty-eight hours and the course can stretch past two weeks.
Fentanyl has complicated the picture. Although it is short-acting when injected in medical settings, illicit fentanyl accumulates in fatty tissue with repeated use and can produce a withdrawal that begins later and lasts longer than heroin's, sometimes with a prolonged, uneven tail. It also makes buprenorphine induction more delicate, because starting buprenorphine while fentanyl is still present can precipitate sudden, severe withdrawal. Clinicians increasingly use modified induction protocols for this reason.
Opioid withdrawal itself is rarely fatal in otherwise healthy adults, though dehydration and cardiac strain can be serious in older or medically fragile people. The lethal risk comes afterward. Tolerance falls quickly during detox, and a return to a previous dose in the first weeks is the most common overdose scenario we see. This is why every client leaving MLJ after opioid detox carries naloxone, and why we discuss continuing buprenorphine or starting extended-release naltrexone with every opioid client before discharge. See our detailed guide to opioid and fentanyl detox for the medication options.
Stimulants: the crash that needs a psychiatrist.
Cocaine and methamphetamine withdrawal do not produce the dramatic physical syndrome of alcohol or opioids, and there is no FDA-approved medication to treat it. What they produce is a crash: profound fatigue, hypersomnia followed by insomnia, intense hunger, a flat or despairing mood, slowed thinking, and, for many people, a craving that feels total. Cocaine's crash begins within hours and its acute phase lasts several days. Methamphetamine's tends to be longer and deeper, with low mood and cognitive slowing that can persist for two weeks or more.
The danger here is psychiatric. Suicidal thinking during a stimulant crash is common enough that we screen for it daily in the first week, and a person who was paranoid or psychotic during heavy use may remain so for days after stopping. Sleep is medically restored where necessary, nutrition is rebuilt, and our psychiatrist sees stimulant clients early and often. The physical phase passes on its own; the work is keeping the person safe and engaged while it does. Our guide to stimulant withdrawal covers the week-by-week course in more detail.
Polysubstance: when the clocks overlap.
Most people who arrive for detox have not been using one substance. Alcohol and benzodiazepines together are common, as are opioids with stimulants, or alcohol with cocaine. Each combination changes the picture. Alcohol plus benzodiazepines compounds seizure risk and makes the taper more complex. Opioids plus stimulants means a physical withdrawal running alongside a psychiatric crash. Alcohol plus cocaine produces cocaethylene in the body, which stresses the heart, and the withdrawal that follows can involve both the alcohol seizure window and the stimulant depression at once.
The clinical rule is simple: plan for the most dangerous substance and monitor for all of them. If alcohol or a benzodiazepine is anywhere in the history, the seizure precautions apply regardless of what else was used. If opioids are present, naloxone and a medication plan are non-negotiable. Honesty on the admissions call about everything you have taken, including cannabis, sleep aids, and anything bought online, is not a moral matter. It is how the medical team decides what to watch for on night two. Our polysubstance detox guide goes deeper.
| Substance | Onset | Peak | Acute phase | Main risk |
|---|---|---|---|---|
| Alcohol | 6–12 hours | 24–72 hours | 5–7 days | Seizures, delirium tremens |
| Benzodiazepines | 1–4 days, by half-life | Week 1–2 | Taper over weeks to months | Seizures with abrupt stop |
| Short-acting opioids | 8–12 hours | 48–72 hours | 5–7 days | Overdose after tolerance drops |
| Fentanyl | Often delayed, 12–36 hours | Days 2–4 | 7–10 days, uneven tail | Overdose; precipitated withdrawal on induction |
| Stimulants | Hours | Days 1–3 | 3–10 days; mood longer | Depression, suicidal thinking |
When detox is medically necessary.
Not everyone who stops using needs a medical detox. Someone who drinks heavily on weekends but not daily, or who used cocaine occasionally, may be able to stop without medical risk, though they may still need treatment for the pattern itself. The question of medical necessity turns on physical dependence and the specific substance. SAMHSA's guidance on detoxification frames it as three components: evaluation, stabilization, and fostering entry into treatment, and it is explicit that detox alone is not treatment (SAMHSA TIP 45).
In practical terms, medical detox is necessary when alcohol has been used daily or near-daily in significant amounts, especially if morning drinking, prior withdrawal symptoms, or a prior seizure are in the history; when any benzodiazepine has been taken daily for more than a few weeks; when opioid dependence is present and the person wants medication support or has medical vulnerabilities; when stimulant use has produced psychosis or suicidal thinking; and whenever more than one of these applies. If you are unsure which category you fall into, our comparison of medical detox versus quitting at home is the place to start, and our full medical detox library covers each substance, the medications used, and how sleep is restored in early recovery.
At MLJ, detox is the first phase of one continuous stay in our six-bed Encino home, with nursing around the clock, a board-certified psychiatrist, and the same clinical team that will carry you through residential and beyond. The admissions call is where we sort out which timeline applies to you.
- Treatment Guidance. Every decision before, during, and after treatment.
- Medical Detox vs. Quitting at Home. Which withdrawals are dangerous and what stopping safely involves.
- What Medically Supervised Means. Nursing, physician oversight, and vitals cadence explained.
- Medical Detox Library. Substance-by-substance detail, medications, and sleep in early recovery.
- Detox and Residential at MLJ. How the first ten days are structured here.
- Nutrition in Alcohol Withdrawal. A blog post on why thiamine matters in the first days.
This guide is educational and is not a substitute for medical advice. If someone is in immediate danger, call 911.