## Acute Opioid Withdrawal: Clinical Presentation **Key Point:** Acute opioid withdrawal is characterized by **mydriasis (dilated pupils) and tachycardia**, reflecting sympathomimetic hyperactivity. While extremely uncomfortable, it is NOT life-threatening. ### Mechanism of Withdrawal **High-Yield:** Opioids suppress noradrenergic neurons in the locus coeruleus. Upon sudden cessation, there is a rebound increase in noradrenergic activity, causing sympathomimetic symptoms. ### Timeline and Symptoms | Symptom | Onset | Peak | Duration | | --- | --- | --- | --- | | **Anxiety, irritability** | 6–12 hrs | 24–48 hrs | 5–7 days | | **Mydriasis** | 8 hrs | 24–48 hrs | 5–7 days | | **Tachycardia, hypertension** | 8–12 hrs | 24–48 hrs | 5–7 days | | **Insomnia, restlessness** | 12 hrs | 24–72 hrs | 1–2 weeks | | **Muscle aches, sweating** | 12–24 hrs | 48–72 hrs | 5–10 days | | **Nausea, vomiting, diarrhea** | 12–24 hrs | 48–72 hrs | 5–10 days | **Mnemonic:** **SWEATING** — Sympathomimetic, Withdrawal, Excitability, Autonomic hyperactivity, Tachycardia, Insomnia, Nausea, GI distress ### Why NOT the Other Options? **Clinical Pearl:** Miosis (pinpoint pupils) and bradycardia are signs of **acute opioid intoxication** (overdose), NOT withdrawal. This is a common exam trap. **Warning:** Seizures and hallucinations are NOT features of uncomplicated opioid withdrawal. They suggest: - Concurrent alcohol or benzodiazepine withdrawal - Underlying seizure disorder - Polydrug use Hypothermia and hypotension are also atypical; withdrawal causes hyperthermia and hypertension due to sympathetic activation. **High-Yield:** Although opioid withdrawal is intensely uncomfortable (insomnia, body aches, anxiety), it is medically safe and does NOT cause death. This contrasts with alcohol or benzodiazepine withdrawal, which can be fatal. [cite:Harrison 21e Ch 395]
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