About This Page
This is a clinician-written, evidence-based guide aligned to the MCC Examination Objectives. It is structured by clinical presentation — the way the MCCQE tests and the way patients actually present. Management reflects current Canadian guidelines (CMA, CFPC, CPS). Always cross-reference with institutional protocols and clinical judgment.
The Bottom Line
- Alcohol and benzodiazepine withdrawal can kill: seizures, delirium, autonomic instability, and hyperthermia require urgent benzodiazepine-based treatment
- Alcohol withdrawal usually begins 6-24h after last drink; seizures often 6-48h; delirium tremens typically 48-96h
- Opioid withdrawal causes mydriasis, yawning, lacrimation, rhinorrhoea, diarrhoea, piloerection, aches, anxiety, and insomnia
- Use CIWA-Ar for alcohol withdrawal in cooperative patients and COWS for opioid withdrawal
- Assess pregnancy, seizures, delirium, comorbid illness, polysubstance use, housing, suicide risk, and previous severe withdrawal before outpatient management
Approach to the Presentation
Substance withdrawal is diagnosed from timing, physiology, and risk. Ask what was used, how much, route, last use, previous withdrawal seizures or delirium tremens, current medications, pregnancy, liver disease, head injury, infection, psychiatric risk, and supports. Alcohol and benzodiazepine withdrawal are GABAergic withdrawal states and can be medical emergencies. Opioid withdrawal is rarely fatal in adults but causes intense distress and relapse risk, especially in the fentanyl era.
Differential Diagnosis
| diagnosis | likelihood | key features | distinguishing test |
|---|---|---|---|
| Severe alcohol withdrawal / delirium tremens | must-not-miss | Tremor, diaphoresis, tachycardia, hypertension, agitation, hallucinations, confusion, fever, seizures | Clinical diagnosis; CIWA-Ar if oriented/cooperative; labs for complications |
| Alcohol withdrawal seizure | must-not-miss | Generalised tonic-clonic seizure 6-48h after last drink, often without focal signs | History, glucose/electrolytes, head injury assessment; CT/EEG if atypical |
| Benzodiazepine or Z-drug withdrawal | must-not-miss | Anxiety, tremor, insomnia, perceptual disturbance, autonomic symptoms, seizures, delirium after abrupt cessation | Medication history, pharmacy records, timing |
| Delirium from infection/metabolic illness | must-not-miss | Confusion, fever, hypoxia, urinary symptoms, pneumonia, electrolyte disturbance; may coexist with withdrawal | Vitals, CBC, electrolytes, renal/liver tests, urinalysis/CXR/cultures |
| Opioid withdrawal | common | Mydriasis, yawning, lacrimation, rhinorrhoea, piloerection, diarrhoea, cramps, myalgias, anxiety, insomnia | COWS score; opioid timeline; avoid precipitated withdrawal |
| Stimulant withdrawal | common | Dysphoria, hypersomnia or insomnia, fatigue, increased appetite, craving, suicidality | Substance history; suicide risk assessment |
| Serotonin syndrome / NMS | less common | Hyperthermia and altered mental status; clonus/hyperreflexia in serotonin syndrome, lead-pipe rigidity in NMS | Medication history and neurological exam |
| Panic/anxiety disorder | less common | Anxiety and palpitations without clear withdrawal timing or objective autonomic withdrawal signs | Timeline, vitals, substance history |
Red Flags & Key History
Symptoms
History of withdrawal seizures or delirium tremens
Confusion, hallucinations with disorientation, fever, severe agitation, or autonomic instability
Pregnancy, older age, significant liver disease, head injury, infection, dehydration, or electrolyte disturbance
Concurrent alcohol + benzodiazepine + opioid use
Suicidal ideation, severe depression, psychosis, or unsafe housing
Last drink/use timing, usual daily amount, longest abstinence, prior treatment episodes
Signs
Tremor, diaphoresis, tachycardia, hypertension, hyperthermia
Seizure, delirium, marked dehydration, or reduced consciousness
Mydriasis, piloerection, rhinorrhoea, yawning, abdominal cramps (opioid withdrawal)
Focal neurological signs after seizure or fall
Approach to Investigation
First-line
Vitals, glucose, hydration, mental statusWithdrawal severity and medical complications can change rapidly
CIWA-Ar for alcohol withdrawalUse in alert/cooperative patients; not reliable in delirium or severe psychosis
COWS for opioid withdrawalGuides buprenorphine/naloxone initiation; start when moderate withdrawal is present
Labs and ECG when moderate-severeCBC, electrolytes, Mg, phosphate, creatinine, liver tests, INR, pregnancy test, ethanol level, ECG
Second-line
Toxicology/co-ingestion testingUrine drug screen, acetaminophen/salicylate levels, and targeted tests when overdose or mixed states possible
Imaging after seizure or traumaCT head if head injury, focal signs, anticoagulation, prolonged confusion, or atypical seizure features
Specialist
Medical admission / monitored withdrawalSevere alcohol/benzodiazepine withdrawal, delirium, seizures, unstable vitals, pregnancy, major comorbidity, unsafe environment
Addiction medicine / RAAMOpioid agonist therapy, alcohol pharmacotherapy, benzodiazepine taper planning, relapse prevention, and harm reduction
Management Principles
CAMH Opioid Use Guidance + Meta:Phi Withdrawal Management Toolkit + CFPC Addiction Medicine resources1
Alcohol withdrawal
- Benzodiazepines are first-line; choose diazepam/lorazepam/chlordiazepoxide based on liver disease, age, and setting
- Give thiamine before glucose when feasible in Wernicke-risk patients; do not delay urgent glucose for hypoglycaemia
- Correct fluids/electrolytes and monitor for seizures and delirium tremens
2
Benzodiazepine withdrawal
- Reinstate a safe benzodiazepine dose if severe withdrawal, then taper gradually, often using a long-acting agent
- Avoid abrupt cessation; monitor for seizures, delirium, suicidality, and polysubstance use
3
Opioid withdrawal
- Assess COWS and timing since last opioid; start buprenorphine/naloxone when moderate withdrawal is present
- Provide symptomatic treatment, naloxone kit, harm reduction, and rapid follow-up because overdose risk rises after abstinence
Complications & Pitfalls
- Undertreating alcohol withdrawal: Delirium tremens and seizures are preventable with adequate benzodiazepine treatment.
- Using CIWA blindly: CIWA-Ar is unreliable in delirium and communication barriers.
- Precipitated opioid withdrawal: Starting buprenorphine too early after fentanyl or long-acting opioids can worsen symptoms.
- Forgetting thiamine: Treat Wernicke risk early in alcohol use disorder.
MCCQE1 Exam Tips
- 1Alcohol withdrawal with seizures or delirium = benzodiazepines and medical monitoring
- 2Delirium tremens is confusion + autonomic instability after alcohol reduction
- 3Opioid withdrawal is unpleasant but usually not fatal in adults; key intervention is opioid agonist treatment
- 4Use COWS before buprenorphine/naloxone to reduce precipitated withdrawal
- 5Benzodiazepine withdrawal can cause seizures — never abruptly stop long-term high-dose benzodiazepines
- 6Thiamine is high-yield in alcohol use disorder
practicetest your knowledge on substance withdrawal (alcohol, opioids, benzodiazepines)Apply what you've learnt with MCCQE1-style questions from the iatroX Q-Bank — psychiatric and beyond.
open q-bank