What is the recommended dosing frequency and dose of Reactine (cetirizine) for adults, breastfeeding mothers, and children?

Reactine (Cetirizine) Dosing Frequency and Recommendations

Reactine (cetirizine) should be taken once daily at a dose of 10 mg for adults and children 6 years and older, with no more than one 10 mg tablet in 24 hours. 1

Standard Adult Dosing

• Adults and children ≥6 years: Take one 10 mg tablet once daily 1
• Do not exceed one 10 mg dose in 24 hours, as higher doses increase sedation risk without necessarily improving efficacy 2
• A 5 mg dose represents only half the therapeutic dose and is considered subtherapeutic for most allergic conditions 2
• Cetirizine has an 8.3-hour elimination half-life and 24-hour duration of action, making once-daily dosing appropriate 2, 3

Pediatric Dosing

• Children 6-11 years: 10 mg once daily provides effective symptom improvement and is well tolerated 4
• Children 2-5 years: 2.5 mg once daily (half the adult dose) 5
• Infants 6-11 months: Oral drops are available for precise dosing 5
• Children under 6 years: Consult a physician for appropriate dosing 1

Timing Considerations

• Cetirizine reaches peak plasma levels within 1 hour, making it advantageous when rapid symptom relief is needed 2, 6
• If sedation occurs: Consider bedtime dosing to allow any mild sedative effects to occur during sleep 2
• Adjust timing to ensure highest drug levels coincide with anticipated symptom periods 5

Special Population Adjustments

Renal Impairment

• Moderate renal impairment (creatinine clearance 10-50 mL/min): Reduce dose to 5 mg once daily 5
• Severe renal impairment (creatinine clearance <10 mL/min): Avoid cetirizine entirely 2, 5
• Hemodialysis patients: Cetirizine is ineffective and not recommended 5

Older Adults

• Adults ≥65 years: Consult a physician before use, as older adults are more sensitive to antihistamine effects 1, 2

Hepatic Impairment

• No dose adjustment needed for hepatic impairment in patients with normal renal function 2

Pregnancy and Breastfeeding

• Ideally avoid during pregnancy, especially in the first trimester (FDA Pregnancy Category B) 5
• Use only if clearly necessary 5

Refractory Cases

• For patients who don't respond adequately to 10 mg daily, dose escalation up to 40 mg daily has become common practice when benefits outweigh risks (Quality of evidence III, Strength of recommendation C) 2, 6
• This is particularly relevant for chronic urticaria and severe pruritic conditions 6

Important Safety Considerations

• Sedation risk: Cetirizine causes mild drowsiness in approximately 13.7% of patients compared to 6.3% with placebo 2, 5
• Patients should be counseled about possible drowsiness, as cetirizine is not completely non-sedating like fexofenadine or loratadine 2
• For patients requiring complete alertness: Consider switching to fexofenadine, which remains completely non-sedating even at higher doses 2
• Avoid combining with other sedating medications without considering additive CNS effects 5

Common Pitfalls to Avoid

• Never combine two different second-generation antihistamines within the same 24-hour period, as safety and efficacy data are lacking 2
• A 24-hour washout is advised before switching between antihistamines 2
• Avoid exceeding one 10 mg dose in 24 hours without medical supervision 1
• For school-age children, consider potential sedative effects that may affect school performance 5