Intake of 8 tablets of cetrizine by adult managemet
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cetirizine overdose 8 tablets 80mg adult management treatment
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https://www.vumc.org/poison-control/toxicology-question-week…
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cetirizine overdose toxicity management
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PMID: 34474941
Here is a structured clinical management guide for cetirizine overdose (8 tablets x 10 mg = 80 mg in an adult):
Cetirizine Overdose - 80 mg in an Adult
Context
- Normal adult dose: 10 mg once daily (max 10 mg/day)
- 80 mg = 8x the therapeutic dose - this meets the threshold for overdose (toxicity typically occurs at 3-5x the usual daily dose)
- Cetirizine is a second-generation H1 antihistamine (piperazine class) with minimal CNS penetration and minimal anticholinergic effects - but both become relevant in overdose
- As per Goodman & Gilman's Pharmacological Basis of Therapeutics, cetirizine "has minimal anticholinergic effects" and "negligible penetration into the brain" at therapeutic doses - but at 80 mg these properties are overcome
Clinical Features Expected (at 80 mg)
Mild-to-moderate features (most likely):
- Sedation, drowsiness, somnolence
- Dizziness, headache, fatigue
- Dry mouth
- Restlessness or paradoxical agitation (especially younger adults)
Moderate-to-severe features (possible at 8x dose):
- Tachycardia
- Mydriasis (dilated pupils)
- Urinary retention
- Confusion or disorientation
- Tremor
Severe/rare features (more typically 1st-gen antihistamines but reported with cetirizine overdose per PMID 34474941):
- Agitation / hallucinations
- Hyperthermia
- Fixed and dilated pupils (full anticholinergic toxidrome)
- Seizures (rare)
Note: A published case report confirmed anticholinergic syndrome from cetirizine overdose - PMID 34474941 (Renko et al., Am J Emerg Med 2022).
Immediate Management
1. Call Poison Control / Emergency Services
- Do NOT manage at home; send to ED immediately
- Poison Control (USA): 1-800-222-1222
2. Airway, Breathing, Circulation (ABCs)
- Assess GCS / level of consciousness
- If unconscious: DO NOT induce vomiting; secure airway
- IV access, cardiac monitor, pulse oximetry, ECG
3. Gastrointestinal Decontamination
- Activated charcoal (1 g/kg PO) - give within 1-2 hours of ingestion IF:
- Patient is alert and able to swallow safely
- Airway is protected
- Gastric lavage: rarely indicated; consider only in massive/recent ingestion with secured airway
- Do NOT induce emesis (risk of aspiration, especially with sedation)
4. Specific Supportive Treatment
| Feature | Treatment |
|---|---|
| Tachycardia | IV fluids (normal saline); treat underlying agitation first |
| Agitation / seizures | Benzodiazepines (lorazepam or diazepam IV) |
| Hyperthermia | Cooling measures (wet cloth, cooling blanket) - avoid antipyretics (not effective for drug-induced hyperthermia) |
| Urinary retention | Urinary catheter (do not miss - can be missed due to delirium) |
| QRS widening (>120 ms) | Sodium bicarbonate IV (if HR >120 and QRS >120 ms) |
| Hypotension | IV fluids; consider norepinephrine if refractory |
| Severe anticholinergic toxidrome | Physostigmine (only under specialist supervision) |
5. ECG Monitoring
- Monitor for QRS widening - though more typical with 1st-gen antihistamines (diphenhydramine), it is possible with large cetirizine doses
- If QRS >120 ms + HR >120: sodium bicarbonate bolus
6. Labs
- Serum electrolytes, renal function (cetirizine is renally excreted)
- Blood glucose
- Urine drug screen (note: cetirizine can cause false-positive TCA screen - Tintinalli's Emergency Medicine)
- CPK/urinalysis if rhabdomyolysis concern (rare but possible)
Observation Period
- Minimum 4-6 hours in the ED, or until completely asymptomatic
- Discharge only when patient is alert, ambulatory, haemodynamically stable, and no new symptoms
No Specific Antidote
There is no antidote for cetirizine. Management is entirely supportive and symptom-directed.
Key Points Summary
| Dose ingested | 80 mg (8x therapeutic) |
| Generation | 2nd gen - lower anticholinergic risk than 1st gen, but still relevant in OD |
| CNS effects | Sedation, confusion, possible agitation |
| Anticholinergic | Can occur in overdose (tachycardia, mydriasis, urinary retention, hyperthermia) |
| Cardiac | QRS widening possible but uncommon |
| Antidote | None |
| Treatment | Supportive - AC, benzos for seizures, cooling, catheter, IV fluids, ECG monitoring |
| Observation | 4-6 hours minimum |
Sources: Goodman & Gilman's Pharmacological Basis of Therapeutics; Tintinalli's Emergency Medicine; Tennessee Poison Center / VUMC Clinical Toxicology; Renko et al., Am J Emerg Med 2022 (PMID 34474941); Canadian Product Monograph for Cetirizine.
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