Opioid withdrawal produces a combination of physical and psychological symptoms that typically feel like a severe flu combined with intense anxiety and drug cravings. Symptoms can begin as early as 6 to 12 hours after the last dose of a short-acting opioid like heroin, and they generally peak within 1 to 3 days before gradually improving over about five days.
Early Physical Symptoms
The first signs of withdrawal are often subtle enough that people mistake them for a cold coming on. Watery eyes, a runny nose, and frequent yawning are among the earliest indicators, usually appearing within hours of a missed dose. Muscle aches, heavy sweating, and chills follow closely behind. Your pupils dilate noticeably, and your heart rate and blood pressure climb above their normal baseline.
These early symptoms are your nervous system reacting to the sudden absence of opioids. While you were using, the drugs suppressed many of your body’s baseline functions. When the drug is removed, those systems rebound and overcorrect, producing symptoms that are essentially the opposite of what opioids do. Where opioids constrict pupils, withdrawal dilates them. Where opioids slow the gut, withdrawal sends it into overdrive.
Later and More Intense Symptoms
Within 24 to 72 hours, the gastrointestinal symptoms hit hardest. Nausea, vomiting, abdominal cramping, and diarrhea are hallmarks of the peak withdrawal period. Goosebumps appear across the skin (this is where the phrase “quitting cold turkey” comes from). Fever and chills can alternate in waves.
The combination of vomiting and diarrhea creates a real risk of dehydration and electrolyte imbalances, particularly for people withdrawing without medical support. Staying hydrated during this phase matters more than most people realize. Severe dehydration can strain the heart and kidneys, making what is already a miserable experience potentially dangerous for people with underlying health conditions.
Psychological Symptoms
The mental side of withdrawal is often harder to endure than the physical side. Anxiety is nearly universal, ranging from a low-level unease to full-blown panic. Irritability spikes, and many people describe feeling emotionally raw, as though every frustration is amplified. Insomnia is common and stubborn. Even when exhaustion sets in, sleep may be broken by restless legs, sweating, or racing thoughts.
The most defining psychological symptom is an intense craving for opioids. Your brain has been running on artificially high levels of its feel-good signaling for weeks, months, or years. When that supply is cut off, the resulting emotional low is steep. Cravings can feel less like a desire and more like a biological need, which is what makes this phase so high-risk for relapse. These cravings persist well beyond the point when physical symptoms have faded.
How the Timeline Varies by Opioid Type
Not all opioid withdrawals follow the same clock. The timeline depends heavily on whether the opioid you were using is short-acting or long-acting.
- Short-acting opioids (heroin, immediate-release prescription painkillers): Withdrawal begins 6 to 12 hours after the last dose, peaks around day 1 to 3, and largely resolves within about five days. The onset is faster, the symptoms hit harder, and the acute phase is shorter.
- Long-acting opioids (methadone, extended-release formulations): Withdrawal may not begin for 24 to 48 hours or longer. Symptoms build more slowly but can stretch over two weeks or more. The intensity at any given moment may be somewhat lower, but the prolonged duration takes its own toll.
Injected forms of any opioid tend to produce a faster onset of withdrawal compared to oral forms, because the drug enters and leaves the bloodstream more quickly.
How Severity Is Measured
In clinical settings, providers use a standardized tool called the Clinical Opiate Withdrawal Scale (COWS) to gauge how severe withdrawal is at any point. It scores 11 observable signs: resting pulse rate, gut symptoms, sweating, tremor, restlessness, yawning, pupil size, anxiety or irritability, bone and joint aches, goosebumps, and runny nose or tearing. Each is rated on a point scale, and the total determines the severity category.
A score of 5 to 12 indicates mild withdrawal. Scores of 13 to 24 fall in the moderate range. Anything from 25 to 36 is moderately severe, and scores above 36 indicate severe withdrawal. This scoring matters because it guides treatment decisions, particularly the timing of medications used to ease symptoms or begin longer-term recovery support.
Post-Acute Withdrawal Syndrome
Many people are surprised to learn that withdrawal doesn’t fully end when the physical symptoms stop. A condition known as post-acute withdrawal syndrome (PAWS) can produce lingering psychological and mood-related symptoms for months, and in some cases, years after the last dose. These symptoms tend to be more emotional than physical: low mood, difficulty concentrating, sleep problems, anxiety, and a general sense of emotional flatness.
PAWS symptoms fluctuate. You might feel fine for a few weeks, then hit a stretch where cravings resurface or your mood dips without an obvious trigger. This unpredictability is a major factor in relapse, because people in recovery may not expect withdrawal-like symptoms to return so long after quitting. Understanding that PAWS is a recognized, well-documented pattern can help you prepare for it rather than being blindsided. The symptoms do eventually resolve, though the timeline is different for everyone.
What Helps During Withdrawal
Medical support during opioid withdrawal significantly improves both comfort and safety. Medications can target specific symptoms: treatments to control nausea and vomiting, others to manage diarrhea and bring down elevated blood pressure, and options to reduce the overall intensity of withdrawal by partially activating the same receptors that opioids bind to. This last approach is the basis of medication-assisted treatment, which has strong evidence for reducing relapse rates.
People who attempt to withdraw on their own face a higher risk of complications from dehydration and a much higher risk of relapse. If relapse occurs after a period of abstinence, the danger is amplified because tolerance drops rapidly during withdrawal. A dose that your body previously handled can become a fatal overdose after even a few days without the drug. This is one of the strongest arguments for withdrawing with medical supervision rather than alone.