Short-acting opioid (heroin, oxycodone) withdrawal begins 6–24 hours after last use, peaks at 36–72 hours, and largely resolves in 5–7 days. Long-acting opioids (methadone) take longer — onset 24–48 hours, resolution 2–3 weeks. Post-Acute Withdrawal Syndrome (PAWS) — mood instability, cravings, sleep disruption — can persist for 3–12 months. MAT (buprenorphine, methadone) eliminates acute withdrawal while reducing overdose mortality by 50%+.
Opioid withdrawal is rarely fatal — but relapse is. Tolerance drops dramatically within days of stopping. Returning to a previous "normal" dose after even a few days of abstinence can cause fatal overdose. This is why the period immediately following detox carries the highest overdose mortality risk. Medication-assisted treatment (MAT) directly addresses this. Call SAMHSA at 1-800-662-4357 to find local treatment.
Why Opioid Withdrawal Happens: The Receptor Science
Opioids bind to mu-opioid receptors throughout the brain and body. With chronic use, receptors downregulate — the brain reduces sensitivity to compensate for constant activation. When opioids are removed, these receptors are suddenly understimulated. The locus coeruleus (the brain's primary norepinephrine center, which regulates arousal, anxiety, and heart rate) goes into overdrive. This produces most of the acute withdrawal symptoms: anxiety, sweating, racing heart, and muscle cramping.
Simultaneously, dopamine systems — suppressed during active use — remain blunted, producing dysphoria, anhedonia, and profound motivational deficits that persist well beyond acute withdrawal as PAWS.
The Timeline: Short-Acting Opioids
Short-acting opioids include heroin, oxycodone (OxyContin), hydrocodone (Vicodin), morphine, and codeine. These have half-lives of 4–8 hours, producing a faster and more intense withdrawal curve.
First Symptoms Appear
Anxiety and restlessness emerge first — a feeling of being in your own skin wrong. Yawning, watery eyes, runny nose, and mild sweating begin. These are primarily driven by the locus coeruleus activating. Many people describe this stage as feeling like "the worst flu coming on." Cravings are intense from the beginning.
Symptoms Escalate
Muscle aches and bone pain develop — "like your bones are breaking" is a common description, reflecting hyperalgesia from opioid receptor rebound. Goosebumps (piloerection, which gives withdrawal its street name "cold turkey") appear. Nausea begins, along with abdominal cramping. Insomnia becomes severe — the restless leg sensation makes lying still nearly impossible. COWS score typically reaches moderate range.
Acute Peak — The Hardest Days
Peak intensity. Vomiting and diarrhea are common and can cause dangerous dehydration — staying hydrated is critical. Vital sign abnormalities: elevated pulse (often 100–120 bpm), hypertension, and temperature dysregulation (alternating hot flashes and chills). Dilated pupils. Extreme restlessness (akathisia). For most people quitting cold turkey, these 72 hours are the hardest they'll experience. COWS often 25+.
Intensity Begins Easing
Physical symptoms start to plateau and slowly decrease. Vomiting typically resolves first, followed by muscle cramps. Sweating and insomnia persist. Energy remains very low — profound fatigue sets in as the body begins repair. Appetite begins returning in some people. Cravings remain severe throughout this phase, making relapse risk extremely high.
Acute Resolution
Most physical symptoms resolve. Lingering symptoms: mild sleep disruption, irritability, low energy, and anxiety. The body has cleared opioids but neurological recalibration is still in early stages. Most people report "feeling almost human again" around day 7-10, though mood remains fragile. The biggest risk here is feeling better and underestimating ongoing recovery needs.
Post-Acute Withdrawal Begins
Sleep quality often worsens again as acute fatigue resolves and insomnia becomes more prominent. Dysphoria and anhedonia — difficulty feeling pleasure, low motivation, emotional flatness — emerge as the dominant symptoms. Anxiety, irritability, and difficulty concentrating persist. Intense cravings can still appear triggered by stress, environments, or sensory cues. This phase catches many people off guard after the relief of clearing acute withdrawal.
PAWS Continuation
Symptoms wax and wane rather than steadily improving. Good days and bad days alternate unpredictably. Mood instability, anxiety spikes, and occasional intense cravings remain. Dopamine system function is gradually recovering — reward sensitivity for everyday activities begins returning. Sleep begins improving for most people. Ongoing support (MAT, counseling, peer support) significantly improves outcomes during this window.
Neurological Recovery
Opioid receptor density recovers significantly over this period. Emotional regulation improves. Sleep normalizes for most people. Cravings become less frequent and intense — they still occur but are more manageable. Motivation and the ability to feel pleasure return. Research shows quality of life markers improve dramatically by the 12-month mark for people in sustained recovery. Many people report feeling better than they have in years.
Long-Acting Opioids: A Different Timeline
Long-acting opioids — particularly methadone (half-life 24–36 hours) and extended-release oxymorphone or oxycodone — produce a delayed, more prolonged withdrawal curve. Buprenorphine (partial agonist, long half-life) is itself used in MAT, so "withdrawal from buprenorphine" is a specific situation that requires medical management.
Methadone Withdrawal: A Different Beast
Onset: 24–48 hours after last dose (sometimes longer, due to the long half-life)
Peak: Days 3–8 — symptoms are typically less intense than short-acting opioid withdrawal but last significantly longer
Duration: 2–3 weeks of significant symptoms, with lingering effects up to 4–6 weeks
The prolonged course makes cold-turkey methadone withdrawal particularly challenging. Medically supervised taper or transition to buprenorphine is strongly preferred over abrupt cessation.
The COWS Scale: How Clinicians Measure Withdrawal
The Clinical Opiate Withdrawal Scale (COWS) is the standard clinical tool for assessing withdrawal severity and timing MAT initiation. It measures 11 signs over a structured assessment. Understanding it helps you communicate with providers.
Clinicians typically initiate buprenorphine when COWS reaches 8–12 — mild-to-moderate withdrawal. Starting too early (before enough opioids have cleared) can precipitate severe withdrawal. This is why "starting Suboxone too soon" is a known risk that needs medical guidance.
PAWS: Post-Acute Withdrawal Syndrome
PAWS is the leading driver of late relapse — many people clear acute withdrawal successfully but relapse weeks or months later when PAWS symptoms become overwhelming. Understanding it matters.
Dysphoria & Anhedonia
Inability to feel pleasure. Everyday activities feel flat. Driven by dopamine receptor desensitization that takes months to reverse.
Sleep Disruption
Difficulty falling and staying asleep. Vivid or disturbing dreams. Often the last symptom to resolve — can persist 3–6 months.
Cognitive Fog
Memory problems, difficulty concentrating, slow processing. Prefrontal cortex function recovers gradually over months.
Anxiety Spikes
Episodic anxiety attacks, often triggered by stress or opioid-associated cues. Hyperactive norepinephrine system recalibrating.
Mood Instability
Emotional swings, irritability, periodic depression. Serotonin and dopamine systems both affected during chronic opioid use.
Cravings
Intense, episodic cravings triggered by stress, environmental cues, or random memory activation. A core PAWS feature that MAT significantly reduces.
Medication-Assisted Treatment (MAT)
MAT isn't a crutch or "trading one addiction for another" — it's evidence-based medicine that reduces overdose mortality by 50%+ and dramatically improves long-term recovery outcomes. SAMHSA, the American Society of Addiction Medicine, and the CDC all recommend MAT as first-line treatment for opioid use disorder.
Buprenorphine (Suboxone)
Partial mu-opioid agonist. Eliminates withdrawal and cravings without producing a significant high (ceiling effect). Office-based prescription — no clinic required. First-line for most patients. Suboxone = buprenorphine + naloxone (prevents injection misuse).
Methadone
Long-acting full agonist. Most effective for severe OUD and patients who don't respond to buprenorphine. Dispensed through licensed OTP clinics (daily pickup initially). Highly regulated but highly effective — reduces overdose risk even more than buprenorphine in some studies.
Naltrexone (Vivitrol)
Monthly injection that fully blocks opioid receptors. No physical dependence risk. Requires complete detox first (7–10 days for short-acting, 10–14 for methadone). Best for motivated patients with strong social support. No craving suppression — pure blocking.
What to Expect: Self-Assessment Checklist
Use this to track your withdrawal and know when to seek additional support.
- I'm aware that tolerance drops rapidly and a previous dose can now cause overdose
- I have a plan if cravings become unmanageable (someone to call, a meeting to go to)
- I'm staying hydrated even when nausea makes it difficult
- I've called SAMHSA (1-800-662-4357) or a local provider to discuss MAT options
- I understand that PAWS can last months and have planned for ongoing support
- I've identified my personal high-risk triggers (places, people, emotional states)
- I know that feeling better after week 1 doesn't mean recovery is over
- I have naloxone (Narcan) accessible in case of relapse — it saves lives
Emergency & Treatment Resources
Frequently Asked Questions
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