What is the recommended oral antihistamine (antihistamine) dose for a child?

Oral Antihistamine Dosing for Children

For children with allergic conditions, second-generation antihistamines (cetirizine or loratadine) are the preferred first-line agents, with specific weight- or age-based dosing that varies by medication. 1, 2

Recommended Second-Generation Antihistamines (First-Line)

Cetirizine

• Ages 2-5 years: 2.5 mg once or twice daily 1
• Ages 6-12 years: 5-10 mg once daily 1
• Ages ≥12 years: 10 mg once daily 1
• Available over-the-counter with excellent safety profile 1

Loratadine

• Ages 2 to under 6 years: 1 teaspoon (5 mg) once daily 2
• Ages 6 years and older: 2 teaspoons (10 mg) once daily 2
• Do not exceed recommended daily dose 2
• Available over-the-counter 1

Fexofenadine

• Ages 2-11 years: 30 mg twice daily 1
• Ages ≥12 years: 60 mg twice daily or 180 mg once daily 1
• Available over-the-counter 1

Desloratadine

• Ages 2-5 years: 1.25 mg once daily 1
• Ages 6-11 years: 2.5 mg once daily 1
• Ages ≥12 years: 5 mg once daily 1
• Requires prescription 1

First-Generation Antihistamines (Use With Caution)

First-generation antihistamines should generally be avoided in children due to sedation, impaired learning, and lack of proven efficacy for common cold symptoms. 3, 4

Diphenhydramine (if absolutely necessary)

• Ages 6 to under 12 years: 10-20 mL (25-50 mg) every 4-6 hours 5
• Ages ≥12 years: 10-20 mL (25-50 mg) every 4-6 hours 5
• Under 6 years: Do not use 5
• Maximum 6 doses in 24 hours 5

Chlorpheniramine (limited indications only)

• Ages 6-12 years: 5 mg intramuscularly or intravenously slowly (for anaphylaxis only) 3
• The American Academy of Pediatrics advises against use for common cold symptoms 3
• Use only for clear allergic indications (allergic rhinitis, urticaria) as diagnosed by a healthcare professional 3

Critical Safety Considerations

Why Second-Generation Antihistamines Are Preferred

• Minimal sedation: First-generation antihistamines cause sedation in >50% of patients at therapeutic doses 4
• No cognitive impairment: Second-generation agents do not adversely affect learning ability 6, 4
• Better safety profile: Third-generation agents (cetirizine, loratadine, fexofenadine, desloratadine) have no clinically relevant cardiac effects or significant drug interactions 4
• Once-daily dosing: Improves compliance compared to multiple daily doses 7

Age-Specific Restrictions

• Most antihistamines lack safety data in children under 2 years of age 8
• Diphenhydramine is contraindicated under age 6 years 5
• Only cetirizine, loratadine, and desloratadine have established safety in children ages 2-5 years 1, 6, 9

Common Pitfalls to Avoid

• Never use first-generation antihistamines for common cold symptoms - efficacy is not established and sedation risks outweigh benefits 3
• Avoid hydroxyzine in renal impairment - reduce dose by 50% in moderate-severe renal disease or avoid entirely if creatinine clearance <10 mL/min 10
• Do not use chlorphenamine in severe liver disease - inappropriate sedating effects 11
• Avoid overdosing - first-generation antihistamine overdoses can cause life-threatening events, though uncommon 4

Special Populations

Renal Impairment

• Reduce hydroxyzine dose by 50% in moderate-severe renal impairment 10
• Consult physician for loratadine dosing in kidney disease 2

Hepatic Impairment

• Consult physician for loratadine dosing in liver disease 2
• Avoid chlorphenamine and hydroxyzine in severe liver disease 11, 10

Pregnancy and Lactation

• Chlorphenamine may be used with caution, particularly avoiding first trimester 11
• Hydroxyzine is contraindicated in early pregnancy 10

Clinical Algorithm for Selection

1. For mild, intermittent allergic symptoms: Start with cetirizine or loratadine based on age-appropriate dosing 6, 7
2. For persistent, severe symptoms: Consider intranasal corticosteroids (fluticasone for ages ≥4 years, mometasone for ages ≥3 years) 6
3. For breakthrough symptoms: Add intranasal antihistamine (azelastine or olopatadine for ages ≥6 years) 1
4. For nighttime symptoms only: Consider adding chlorphenamine 4-12 mg at bedtime to non-sedating daytime antihistamine, though this provides minimal additional benefit if H1 receptors already saturated 11