For short-acting opioids like heroin and oxycodone, the worst of physical withdrawal typically lasts four to five days. For longer-acting opioids like methadone, symptoms can stretch across several weeks. But those timelines only cover the acute phase. A second wave of psychological symptoms can persist for months, and fentanyl has introduced a new pattern that doesn’t follow the traditional short-acting playbook.
Short-Acting Opioids: Heroin, Oxycodone, Hydrocodone
With short-acting opioids, withdrawal symptoms generally begin 8 to 24 hours after the last dose. The earliest signs are subtle: yawning, a runny nose, watery eyes, and a growing sense of restlessness. These can feel like the start of a bad flu, and many people initially mistake them for exactly that.
Over the next 24 to 72 hours, symptoms intensify. This is the peak period, when muscle and joint aches become severe, nausea and diarrhea set in, sweating increases, and sleep becomes nearly impossible. Heart rate climbs, pupils dilate noticeably, and anxiety or irritability can make it hard to stay still for more than a few seconds. By days four and five, physical symptoms are fading significantly. Most people feel markedly better by the end of the first week, though fatigue and disrupted sleep often linger longer.
Long-Acting Opioids: Methadone and Similar Drugs
If you’ve been using methadone or another slow-release opioid, the timeline stretches out in both directions. Withdrawal symptoms typically don’t appear until one to three days after the last dose, because the drug clears your system more slowly. The tradeoff is that symptoms are generally less intense at their peak than they are with heroin or oxycodone. The downside is duration: the full withdrawal process can take a few weeks rather than a few days. This extended timeline can be psychologically exhausting, even when the day-to-day severity is more manageable.
Fentanyl Changes the Timeline
Fentanyl is estimated to be 50 to 100 times more potent than morphine, and it behaves differently in the body than traditional short-acting opioids. It’s highly lipophilic, meaning it dissolves into fat tissue and can redistribute from those stores back into the bloodstream over time. This creates a withdrawal pattern that doesn’t match the neat four-to-five-day window people expect from other short-acting opioids.
Preliminary research is showing that fentanyl’s elimination from the body is highly variable but consistently prolonged. In one ongoing outpatient study, most participants were still testing positive for fentanyl on days 8, 9, and 10 after stopping use, well beyond the two-to-four-day clearance window typical for short-acting opioids. This means withdrawal symptoms can come in waves, with periods of improvement followed by “rebounds” as fentanyl stored in tissue re-enters circulation. For people trying to transition onto maintenance medications, this unpredictable release creates real clinical challenges and can trigger unexpected withdrawal episodes days into treatment.
What Symptoms Feel Like at Each Stage
Clinicians track withdrawal severity using an 11-item scoring tool that rates physical signs on a numerical scale. Understanding the benchmarks gives you a realistic picture of what each phase feels like from the inside.
In the early, mild stage, you might notice your pulse creeping above 80 beats per minute, mild stomach cramps, occasional yawning, and a vague achiness in your muscles and joints. You can still sit still, but you feel restless. Your nose starts running for no reason.
At moderate severity, symptoms are unmistakable. Your pulse may be above 100, nausea or loose stools have set in, visible sweat appears on your face, and your pupils are noticeably dilated. Anxiety becomes obvious, not just an internal feeling. Joint and muscle pain shifts from diffuse discomfort to severe aching.
At the most severe end, your pulse can exceed 120, vomiting and diarrhea come in repeated waves, and goosebumps are prominently visible on your arms. Restlessness becomes so intense that sitting still for more than a few seconds feels physically impossible. Pupils dilate so widely that only the rim of the iris remains visible. This peak intensity is temporary, usually lasting 24 to 48 hours, but it’s the period most people describe as unbearable.
Why Withdrawal Happens in the First Place
Opioids work by binding to receptors in your brain that naturally dampen pain signals, slow your heart rate, calm your gut, and produce feelings of relaxation. When you use opioids repeatedly, your cells adapt. They compensate for the constant suppression by ramping up their baseline activity, essentially turning up the volume to counteract the drug’s quieting effect.
When you stop taking the drug, that compensatory overdrive is suddenly unopposed. A key part of this involves a signaling molecule called cAMP, which your cells have been overproducing to compensate for opioid suppression. Without the drug, cAMP levels spike dramatically. This “overshoot” is what drives many of the classic symptoms: the racing heart, the sweating, the diarrhea, the anxiety. A brain region involved in alertness and stress response becomes hyperactive during withdrawal, which is why restlessness, sweating, and a pounding heart are so prominent. These cellular changes are temporary, and your body gradually recalibrates, but the process takes days to weeks depending on how deeply adapted your system has become.
Post-Acute Withdrawal Syndrome
Once the physical symptoms resolve, many people enter a second phase known as post-acute withdrawal syndrome, or PAWS. This phase is psychological and mood-related rather than physical. Symptoms include persistent anxiety, irritability, difficulty concentrating, low motivation, mood swings, and disrupted sleep. PAWS can last for months to years after acute withdrawal ends.
This phase catches people off guard. The physical crisis is over, so they expect to feel normal, but instead they feel flat, emotionally fragile, or unable to experience pleasure the way they used to. PAWS is a major driver of relapse because the prolonged discomfort can feel like it will never end. Recognizing it as a predictable, named phase of recovery, not a personal failure, makes a meaningful difference in how people navigate it.
Medications That Affect the Timeline
Two main approaches are used to manage the acute withdrawal period, and they affect the timeline differently. One involves medications that act on the same type of brain receptors responsible for the stress-response overdrive during withdrawal. According to a large Cochrane review, these medications significantly reduce the likelihood of severe withdrawal compared to placebo. Withdrawal signs tend to appear and resolve earlier with this approach, compressing the timeline somewhat. However, peak severity can feel slightly more intense compared to a gradual taper.
The other approach is a slow, controlled taper using a long-acting opioid substitute. This stretches the process out over a longer period but keeps day-to-day severity lower and produces fewer side effects. Treatment in most clinical studies lasted one to two weeks, with some extending up to 30 days. Neither approach eliminates withdrawal entirely, but both make the acute phase significantly more manageable.
Factors That Shift Your Timeline
No two people experience withdrawal on exactly the same schedule. Several variables influence how quickly symptoms appear, how intense they get, and how long they last. The type of opioid matters most, as discussed above, but within each category there’s still wide variation.
- Duration of use: Someone who used opioids daily for years has deeper cellular adaptations than someone who used for a few weeks. Longer use generally means a longer, more intense withdrawal.
- Dose: Higher daily doses create stronger dependence and typically produce more severe symptoms.
- Individual metabolism: How quickly your body clears a drug affects onset timing. Faster metabolizers may feel symptoms sooner.
- Polysubstance use: Using opioids alongside benzodiazepines, alcohol, or stimulants complicates withdrawal because multiple systems are disrupted simultaneously.
- Overall health: Chronic illness, poor nutrition, and dehydration can all intensify symptoms and slow recovery.
For a rough framework: expect the acute physical phase to last 5 to 10 days for most opioids, with fentanyl potentially extending that window. Expect mood and sleep disruptions to take weeks or months to fully resolve. And expect that the timeline is a range, not a fixed schedule. Your body will set its own pace.