Allergic rhinitis
First line
First-line allergic rhinitis treatment per ARIA. Efficacy is confirmed in numerous RCTs. Advantage over cetirizine: minimal drowsiness, which matters for drivers and precision workers. Adult dose is 10 mg once daily.
Loratadine
Second-generation antihistamines
ATC code: R06AX13 (Loratadine)
Mechanism of action
Long-acting peripheral H1-receptor antagonist. Virtually no CNS penetration, resulting in minimal sedation. Hepatic metabolism via CYP3A4 and CYP2D6 produces the active metabolite desloratadine. Onset of action 1-3 hours, duration exceeding 24 hours.
Indications
Chronic urticaria
First line
First-line treatment for chronic urticaria. As with cetirizine, up-dosing to 4-fold is permitted per EAACI/GA2LEN guidelines if the standard dose is insufficient. Higher doses are well tolerated without significant increase in sedation.
Common cold
Not recommended
Loratadine does not work for the common cold. The 2015 Cochrane review «Antihistamines for the common cold» showed second-generation H1 antagonists do not improve cold symptoms. Only first-generation H1 drugs show a weak effect through their anticholinergic action, which loratadine largely lacks. AAP, NICE, and CDC do not include antihistamines in common cold recommendations. Widespread use in post-Soviet countries is inconsistent with the evidence base.
Infectious conjunctivitis
Not recommended
Systemic loratadine is not used in viral or bacterial conjunctivitis. The AAO Preferred Practice Pattern distinguishes allergic conjunctivitis, where H1 blockers work, from infectious, where histamine is not involved in pathogenesis. Viral cases are treated symptomatically (cold compresses, artificial tears), bacterial with topical antibiotics.
Non-allergic rhinitis
Not recommended
Loratadine is not used in non-allergic rhinitis (vasomotor, idiopathic, infectious URI-related, medication-induced). ARIA 2020 and EAACI separate allergic and non-allergic rhinitis: systemic H1 blockers are not useful in the latter because the pathogenesis is not histamine-mediated. Topical azelastine and corticosteroids work for vasomotor rhinitis.
Pre-vaccination premedication for reaction prevention
Not recommended
Routine loratadine before planned vaccination in healthy people without allergy history is not supported by international societies. CDC Pink Book, ACIP 2023, and WHO: antihistamine premedication does not prevent anaphylaxis because the anaphylactic cascade outpaces H1 blockade. Selected RCTs show reduced vaccine immunogenicity of 10–25 % with antihistamine and antipyretic premedication (Prymula R et al. Lancet 2009). Patients with confirmed drug or vaccine allergy are managed individually by an allergist.
Practical notes
Timing and administration
Take 10 mg once daily at any time. Onset is 1-3 hours, slightly slower than cetirizine. For people needing minimal drowsiness – drivers, students – loratadine is preferred. Available OTC in most countries.
Special situations
In severe hepatic impairment or CrCl below 30 mL/min, the starting dose is reduced to 10 mg every other day. Loratadine is metabolized via CYP3A4 – inhibitors such as ketoconazole and erythromycin increase its levels, but without meaningful QT prolongation.
Common myths
Loratadine is prescribed in post-Soviet countries for a wide range of conditions where it does not work. Common unfounded uses include the following.
Myth: «loratadine for a cold and runny nose». Fact: second-generation H1 blockers do not work in URI. The 2015 Cochrane review confirmed the null effect on 5,099 participants. Short-course nasal decongestants and saline rinses help cold symptoms.
Myth: «loratadine for any rhinitis, not just allergic». Fact: ARIA clearly separates allergic and non-allergic rhinitis. In vasomotor, idiopathic, infectious, and medication-induced rhinitis, systemic H1 blockers do not work – histamine is not the key mediator in pathogenesis.
Myth: «loratadine before a shot to avoid reactions». Fact: CDC, ACIP, and WHO do not support this practice. Antihistamines do not prevent anaphylaxis. In selected RCTs, antihistamine and antipyretic premedication reduced vaccine immunogenicity by 10–25 %.
Myth: «loratadine for eye redness or irritation». Fact: in viral or bacterial conjunctivitis, systemic antihistamines do not work. AAO recommends symptomatic treatment for viral and topical antibiotics for bacterial cases.
Loratadine and cetirizine are first-line only in IgE-mediated allergy: allergic rhinitis, urticaria, allergic conjunctivitis. In other situations, their use is at best useless and at worst reduces the efficacy of the core therapy or vaccination.
Myth: «loratadine for a cold and runny nose». Fact: second-generation H1 blockers do not work in URI. The 2015 Cochrane review confirmed the null effect on 5,099 participants. Short-course nasal decongestants and saline rinses help cold symptoms.
Myth: «loratadine for any rhinitis, not just allergic». Fact: ARIA clearly separates allergic and non-allergic rhinitis. In vasomotor, idiopathic, infectious, and medication-induced rhinitis, systemic H1 blockers do not work – histamine is not the key mediator in pathogenesis.
Myth: «loratadine before a shot to avoid reactions». Fact: CDC, ACIP, and WHO do not support this practice. Antihistamines do not prevent anaphylaxis. In selected RCTs, antihistamine and antipyretic premedication reduced vaccine immunogenicity by 10–25 %.
Myth: «loratadine for eye redness or irritation». Fact: in viral or bacterial conjunctivitis, systemic antihistamines do not work. AAO recommends symptomatic treatment for viral and topical antibiotics for bacterial cases.
Loratadine and cetirizine are first-line only in IgE-mediated allergy: allergic rhinitis, urticaria, allergic conjunctivitis. In other situations, their use is at best useless and at worst reduces the efficacy of the core therapy or vaccination.
Safety
Contraindications
- Hypersensitivity to loratadine or desloratadine
Serious adverse effects
- Severe allergic reactions (very rare)
Common adverse effects
- Headache
- Dry mouth
- Fatigue (rare)
PregnancyFDA B
FDA category B. Considered a preferred antihistamine in pregnancy alongside cetirizine. Large cohort studies have not identified an increased risk of congenital malformations.
Breastfeeding
Passes into breast milk in negligible amounts. Compatible with breastfeeding per LactMed.