Cetirizine
Cetirizine hydrochloride
Brand names:Zyrtec, All Day Allergy
A second-generation H1 antihistamine with faster onset than loratadine but mild sedation in a minority of users. Cetirizine is the fastest-acting of the three operational non-sedating antihistamines (loratadine, cetirizine, fexofenadine), useful for acute urticaria or new-onset allergic symptoms requiring rapid relief without the operational cost of diphenhydramine.
Pharmacology and Actions
Cetirizine is a second-generation peripheral H1 antihistamine, the carboxylic acid metabolite of hydroxyzine. Selectively antagonizes H1 receptors with much less blood-brain barrier penetration than first-generation antihistamines. More sedating than loratadine and fexofenadine in 10 to 15 percent of users, less than diphenhydramine. Minimal anticholinergic activity.
Indications
- Seasonal and perennial allergic rhinitis
- Chronic urticaria (often first-line)
- Acute urticaria requiring rapid antihistamine effect
- Allergic conjunctivitis
- Mild to moderate allergic reactions in operational personnel
Absolute Contraindications
- Known hypersensitivity to cetirizine, hydroxyzine, or levocetirizine
Precautions and Side Effects
Common: drowsiness (10 to 15 percent; the operational distinguisher from loratadine and fexofenadine), dry mouth, fatigue, headache. Cardiac: no significant QT effects at recommended doses. Drug interactions: minimal; additive sedation with CNS depressants is the main concern; theophylline may slightly increase cetirizine levels. Half-life 8 to 10 hours. Pregnancy Category B (extensively used in pregnancy). Compatible with lactation. Pediatric use approved from 6 months. Renal impairment: reduce dose by 50 percent if CrCl under 30. Hepatic impairment: reduce dose. Test individual tolerance during training before relying on it operationally - some operators experience meaningful sedation; most do not.
Adult Dosing
Pediatric Dosing
Children 6 to 23 months: 2.5 mg PO once daily. Children 2 to 5 years: 2.5 mg PO once or twice daily; max 5 mg per 24 hours. Children 6 years and older: 5 to 10 mg PO once daily.
Pharmacokinetics
Peak Effect: 1 hour.
Duration: 24 hours.
Storage and Handling
Store at room temperature (15 to 30 degrees C). Protect from light and moisture. Stable in standard aid bag and IFAK conditions.
Reconstitution:
Oral formulation only. No reconstitution required.
TCCC and TECC Role
Cetirizine is not in the TCCC core formulary. It appears in tactical EMS supplemental formularies and deployment medical kits as the rapid-onset second-generation antihistamine for acute allergic symptoms when speed matters more than absolutely zero sedation. Mission impact is minor at standard doses for most operators; test tolerance individually. Not appropriate for anaphylaxis - epinephrine and diphenhydramine remain the doctrine.
Cetirizine bridges the gap between fast-onset first-generation antihistamines (diphenhydramine, with significant sedation) and slow-onset second-generation antihistamines (loratadine, with minimal sedation). For an operator who develops acute urticaria, swelling, or pruritus and needs symptom relief within an hour while preserving most operational capacity, cetirizine is a reasonable choice. For chronic daily use during a deployment, loratadine or fexofenadine are usually preferred. Individual response varies enough that operators should test tolerance during training.
Assuming cetirizine is fully non-sedating because it is labeled second-generation. About 10 to 15 percent of users experience meaningful drowsiness. Operators should test their individual response during training, not first encounter the sedation during a real operation. The other mistake is using cetirizine for acute anaphylaxis - epinephrine is required; second-generation antihistamines have no role in that setting.
This drug profile is provided as educational reference material for trained medical providers. It is not medical advice, not a substitute for formal training, and not a substitute for current published guidelines or medical direction.
Drug administration is governed by your scope of practice, agency standing orders, medical director protocols, and applicable state and federal regulations. Controlled substances are subject to additional handling, accountability, and documentation requirements per DEA and state law. Always verify dosing, indications, contraindications, and route of administration against current published guidelines and your local protocols before administration.
If this content is being viewed during a medical emergency, call 911 immediately and follow the direction of your local emergency dispatch and medical control. Do not use this reference as a substitute for emergency medical services.
Drug information evolves. Last reviewed dates and source citations are provided for each entry. Confirm currency against the cited source before clinical use.
Penn Tactical Solutions publishes this reference for educational purposes. PTS does not provide medical direction and does not assume responsibility for clinical decisions made in the field. Clinical responsibility rests with the administering provider, their medical director, and their agency.
Educational reference for trained medical providers. Not medical advice. Not a substitute for formal training, current published guidelines, or medical direction. Drug administration is governed by your scope of practice, agency standing orders, medical director protocols, and applicable state and federal regulations. Controlled substances require additional storage, accountability, and documentation per DEA and state law.
In a medical emergency, call 911. This reference is not a substitute for emergency medical services.
Verify dosing, indications, and contraindications against current published guidelines and your local protocols before administration. Confirm content currency against the source citation. Penn Tactical Solutions does not provide medical direction. Clinical responsibility rests with the administering provider, their medical director, and their agency.
Cetirizine
| IV/IO | None (None) |
| IM | None (None) |
| IN | None (None) |
| PO | 10 mg PO once daily. Maximum 10 mg per 24 hours in most patients. Available as tablet, ODT (orally disintegrating), chewable, and liquid. (20 to 60 minutes (faster than loratadine)) |