A second-generation antihistamine with minimal sedative effects, used for the symptomatic relief of seasonal and perennial allergic rhinitis and chronic idiopathic urticaria. One of the least sedating oral antihistamines due to very limited CNS penetration. Available over-the-counter and widely used for its favorable tolerability profile. Active metabolite desloratadine (Clarinex) is also marketed separately.
Known hypersensitivity to loratadine or desloratadine1,2
Severe hepatic impairment (dose adjustment: 10 mg every other day)
The bottom line
Evidence rating strong. Most-documented uses: relieves allergic rhinitis symptoms (sneezing, itching, rhinorrhea), treats chronic idiopathic urticaria, minimal sedation (less than cetirizine). 11 sources indexed (1998–2025), with 1 interaction record on file.
The science
How it works, mechanistically.
Core mechanism
A long-acting selective peripheral H1 receptor antagonist. Competitively blocks H1 histamine receptors on target cells, preventing the vasodilatory, permeability-enhancing, and pruritic effects of histamine released during allergic reactions. Also inhibits histamine release from mast cells. At therapeutic doses, loratadine does not significantly cross the blood-brain barrier (P-glycoprotein substrate), resulting in minimal CNS sedation and no significant anticholinergic effects.
Class
Second-Generation Antihistamine
Dosing
Dosing & protocol.
Common range
Adults and children >=6 years: 10 mg once daily; children 2-5 years: 5 mg once daily (as prescribed by your physician)
Recommended form
Oral tablets, orally disintegrating tablets (Reditabs), or liquid syrup
Rapidly absorbed; food delays absorption by approximately 1 hour but does not affect total bioavailability. Can be taken with or without food. Extensively metabolized by CYP3A4 and CYP2D6 to active metabolite desloratadine.
Safety
Full safety detail.
Side effects
Headache
Drowsiness (uncommon, near placebo rates)
Fatigue
Dry mouth
Nervousness (children)
Contraindications
Known hypersensitivity to loratadine or desloratadine1,2
Severe hepatic impairment (dose adjustment: 10 mg every other day)
Severe renal impairment (GFR <30 mL/min, dose adjustment: 10 mg every other day)
Loratadine is much less sedating than older antihistamines, and controlled testing did not find meaningful driving or psychomotor impairment from a standard 10 mg dose, even when alcohol was included in the study design. Alcohol itself still impaired performance in that trial, and some people can feel drowsy on loratadine. The practical risk is highest before driving, in older adults, with higher-than-labeled loratadine doses, or when other sedatives are also present.
Recommendation: Use extra caution with alcohol until you know how loratadine affects you. Do not drive, operate machinery, or do safety-sensitive work after drinking, even if loratadine is not making you sleepy. Avoid adding cannabis, sleep aids, or other sedating products on the same day.
Wang H, Ji Q, Liao C et al.. A systematic review and meta-analysis of loratadine combined with montelukast for the treatment of allergic rhinitis. Frontiers in pharmacology. 2023
Mösges R, König V, Köberlein J. The effectiveness of levocetirizine in comparison with loratadine in treatment of allergic rhinitis--a meta-analysis. Allergology international : official journal of the Japanese Society of Allergology. 2011
Schwarz EB, Moretti ME, Nayak S et al.. Risk of hypospadias in offspring of women using loratadine during pregnancy: a systematic review and meta-analysis. Drug safety. 2008
Nayak AS, Berger WE, LaForce CF et al.. Randomized, placebo-controlled study of cetirizine and loratadine in children with seasonal allergic rhinitis. Allergy and asthma proceedings. 2017
Kaiser HB, Banov CH, Berkowitz RR et al.. Comparative efficacy and safety of once-daily versus twice-daily loratadine-pseudoephedrine combinations versus placebo in seasonal allergic rhinitis. American journal of therapeutics. 1998
Yong H, Di L, Wang Z et al.. Efficacy and safety of combined loratadine and mometasone furoate therapy in allergic rhinitis patients. Frontiers in immunology. 2025
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