Can Claritin (Loratadine) Be Taken Twice Daily?
No, loratadine should not be taken twice daily—the FDA-approved dosing is 10 mg once daily for adults and children 6 years and older, and exceeding this dose may cause drowsiness without additional therapeutic benefit. 1
FDA-Approved Dosing
The official FDA labeling is explicit about loratadine dosing:
- Adults and children ≥6 years: 10 mg once daily (do not exceed 10 mg in 24 hours) 1
- Children 2 to <6 years: 5 mg once daily 1
- Taking more than the directed dose may cause drowsiness 1
Clinical Evidence Supporting Once-Daily Dosing
Loratadine is specifically designed as a once-daily antihistamine with a duration of action of at least 24 hours. 2 The pharmacokinetic profile supports this dosing schedule:
- Peak plasma concentration occurs in 1-2 hours 2
- The active metabolite (descarboethoxyloratadine) has an elimination half-life of approximately 20 hours 2
- Onset of action is within 1 hour with duration lasting at least 24 hours 2
Comparative Studies: Once vs. Twice Daily
A head-to-head pharmacokinetic study directly compared once-daily (10 mg) versus twice-daily (5 mg BID) loratadine formulations and found that both regimens produced equivalent drug exposure (AUC) over 24 hours after multiple dosing. 3 This means splitting the dose provides no pharmacokinetic advantage.
In a clinical efficacy trial for seasonal allergic rhinitis, both once-daily and twice-daily loratadine-pseudoephedrine combinations were equally effective, but the once-daily formulation caused significantly less insomnia (4% vs. 15%, p<0.01). 4
Guideline Recommendations for Urticaria
British guidelines for urticaria management confirm that loratadine is taken once daily among the seven nonsedating H1 antihistamines licensed for urticaria. 5 When standard doses are insufficient, guidelines recommend increasing the dose above the manufacturer's recommendation (e.g., doubling to 20 mg once daily) rather than splitting into twice-daily dosing. 5
The American Academy of Allergy, Asthma, and Immunology supports doubling the cetirizine dose to 20 mg once daily for refractory urticaria, demonstrating that dose escalation as a single daily dose is the preferred strategy over divided dosing. 6
Critical Clinical Pitfalls
- Do not split loratadine into twice-daily dosing—this is not FDA-approved and offers no therapeutic advantage 1, 3
- If standard 10 mg once daily is insufficient, consider doubling to 20 mg once daily (off-label but guideline-supported) rather than BID dosing 5
- Patients with liver or kidney disease should consult a physician before any dosing adjustments 1
- Exceeding recommended doses increases drowsiness risk without improving efficacy 1