Loratadine

Second-generation antihistamines

ATC code: R06AX13

Updated 24 Sep 2026 · Methodology

Indications

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.

Sources

J Allergy Clin Immunol: Allergic Rhinitis and its Impact on Asthma (ARIA) guidelines: 2010 revision. (2010)
J Allergy Clin Immunol: Allergic Rhinitis and its Impact on Asthma (ARIA) guidelines-2016 revision. (2017)
J Allergy Clin Immunol: The diagnosis and management of rhinitis: an updated practice parameter. (2008)
Braz J Otorhinolaryngol: Efficacy of different oral H(1) antihistamine treatments on allergic rhinitis: a systematic review and network meta-analysis of randomized controlled trials. (2023)
BMJ: Sedation with "non-sedating" antihistamines: four prescription-event monitoring studies in general practice. (2000)

ICD-10: J30.9 · ICD-11: CA08.0

Chronic urticaria

First line

First-line treatment for chronic urticaria. If the standard dose is insufficient, /GA2LEN permit up-dosing second-generation antihistamines up to 4-fold as a class-level recommendation; loratadine-specific up-dosing data are limited. Higher doses are usually tolerated acceptably.

Sources

ICD-10: L50.1 · ICD-11: EB00.1

Marketing claims without evidence base

The drug is promoted for these uses outside international guidelines. Each entry below is analyzed against AEMPS, FDA, EMA, Cochrane and major RCTs.

Infectious conjunctivitis

Not recommended

Loratadine is an oral antihistamine used for allergic rhinitis and hives. It is sometimes suggested for infectious conjunctivitis too, but no convincing benefit has been shown for this use: the inflammation in an infection comes from viruses or bacteria, not from the histamine response that loratadine acts on. What actually helps with infectious conjunctivitis targets the cause – eye hygiene and rinsing, and for bacterial cases topical antibacterial drops prescribed by a doctor. The substance itself is harmless in this role, but do not use it in place of treatment with proven benefit, or you may miss the care you need.

Sources

Ophthalmology: Conjunctivitis Preferred Practice Pattern (2024)

ICD-10: H10.0 · ICD-11: 9A60.3

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. , , and CDC do not include antihistamines in common cold recommendations. Widespread use in post-Soviet countries is inconsistent with the evidence base.

Sources

ICD-10: J00 · ICD-11: CA00

Non-allergic rhinitis

Not recommended

Loratadine is not used in non-allergic rhinitis (vasomotor, idiopathic, infectious URI-related, medication-induced). ARIA 2020 and 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.

Sources

ICD-10: J30.0 · ICD-11: CA08.1

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 : 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.

Sources

ICD-10: Z29.8

How to read tiers A–F

AStrong evidence – first or second line in international guidelines
BRecommended in selected cases
CStudy data contradict each other
DBenefit not proven, no documented harm
FDocumented harm, or risk without benefit

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.

Safety

Contraindications

Hypersensitivity to loratadine or desloratadine

Serious adverse effects

Severe allergic reactions (very rare)

Common adverse effects

Headache
Dry mouth
Fatigue (rare)

Pregnancy: can you take Loratadine?

AEMPS summary of product characteristics (section 4.6): a large amount of data from pregnant women (more than 1,000 pregnancy outcomes) indicates no malformations or fetal or neonatal toxicity with loratadine. Animal studies do not show direct or indirect harmful effects with respect to reproductive toxicity. As a precaution, it is preferable to avoid loratadine during pregnancy.

Breastfeeding: can you take Loratadine?

Hale L1 · Compatible

Passes into breast milk in negligible amounts. Compatible with breastfeeding per LactMed.

RID, infant dose via milk: 0.04%
Maternal half-life: 11.0 h
Maternal peak time: 1.5 h
Peak milk concentration: 0 mg/L
Milk-to-plasma ratio: 1.2

Calculate RID Safe feeding window Full profile on NIH LactMed ↗

Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.

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 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. 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.

Drug–drug interactions

4 pairs found. Sorted from critical to minor.

ModerateAmiodaroneClass III antiarrhythmics (Vaughan Williams)

Mechanism

Loratadine causes minimal QT prolongation at standard doses, but with CYP3A4 blockade by amiodarone, loratadine levels rise, potentially amplifying cardiac effects in predisposed patients.

Symptoms

QT prolongation on ECG. Dizziness, syncope, palpitations. Rarely: polymorphic ventricular tachycardia (torsades de pointes). Risk is higher with hypokalaemia, hypomagnesaemia, bradycardia, and ischaemic heart disease.

Management

Standard loratadine 10 mg/day is kept. In patients with prior QT prolongation, hypokalaemia, or bradycardia below 60 bpm, switch to cetirizine (minimal QT effect). Check ECG every 3–6 months on the combination.

Sources

FDA: Amiodarone hydrochloride tablet (Dr. Reddy's Labratories Inc.) – Prescribing Information (2018)

Pair details →Amiodarone →

ModerateDiazepamAnxiolytics. Benzodiazepine derivatives

Mechanism

Loratadine rarely causes sedation at standard doses. With diazepam, mild additive CNS depression is possible, especially in older patients.

Symptoms

Sedation, fatigue, slowed reactions, impaired coordination. In older patients: fall and fracture risk. Driving and operating machinery: accident risk.

Management

On standard loratadine (10 mg/day) with intermittent diazepam (e.g. for anxiety), no adjustment needed. In older patients and on long-term benzodiazepine therapy, watch for sedation signs. For anxiety disorders, consider alternatives to diazepam: buspirone or CBT.

Sources

FDA: Tylenol 8 HR Arthritis Pain (acetaminophen) – label (2020)

Pair details →Diazepam →

ModerateMorphineNatural opium alkaloids

Mechanism

Loratadine is a second-generation antihistamine with minimal blood-brain barrier penetration. With opioids, mild additive CNS depression is possible, especially in older patients.

Symptoms

Sedation, fatigue, slowed reactions, impaired coordination. In older patients: fall and fracture risk. Driving and operating machinery: accident risk.

Management

No dose adjustment needed. In older patients and palliative care, watch for sedation signs. Loratadine is preferred over cetirizine or chlorpheniramine on concurrent opioid therapy — minimal sedation. With marked sedation, stop the antihistamine.

Sources

FDA: Tylenol 8 HR Arthritis Pain (acetaminophen) – label (2020)

Pair details →Morphine →

MinorParacetamolAnilides. Analgesics and antipyretics

Mechanism

Paracetamol and loratadine are metabolised by different pathways. No direct pharmacokinetic interaction.

Symptoms

The combination usually causes no specific symptoms. Each drug's individual side effects remain.

Management

No dose adjustment needed. The combination is standard in symptomatic formulations for acute respiratory infections and allergy.

Sources

FDA: Tylenol 8 HR Arthritis Pain (acetaminophen) – label (2020)

Pair details →Paracetamol →

Label mentions5 mentions

Verbatim lines from the interaction sections, in the language of the label

From this drug’s label

Erythromycin
«En ensayos clínicos controlados, se ha comunicado un aumento de las concentraciones plasmáticas de loratadina tras el uso concomitante con ketoconazol, eritromicina y cimetidina, pero sin…»
AEMPS, section 4.5 · Open on CIMA
Ketoconazole
«En ensayos clínicos controlados, se ha comunicado un aumento de las concentraciones plasmáticas de loratadina tras el uso concomitante con ketoconazol, eritromicina y cimetidina, pero sin…»
AEMPS, section 4.5 · Open on CIMA

From other drugs’ labels

ModerateRitonavir
«Antihistamínicos: La administración de ritonavir dosificado como potenciador farmacocinético o de agente antirretroviral inhibe la CPY3A y como resultado se espera el aumento de la concentración…»
AEMPS, section 4.5 · Open on CIMA
Carbamazepine
«Fármacos que pueden aumentar los niveles plasmáticos de la carbamazepina: Antihistamínicos: terfenadina, loratadina.»
AEMPS, section 4.5 · Open on CIMA
Mometasone
«Se llevó a cabo un estudio de interacciones clínicas con la loratadina. No se han observado interacciones.»
AEMPS, section 4.5 · Open on CIMA

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Frequently asked

What is Loratadine used for?

Loratadine is evaluated for the following indications with varying evidence strength: Chronic urticaria (evidence tier A), Allergic rhinitis (evidence tier A), Infectious conjunctivitis (evidence tier D). See the full indication matrix with dosing and citations above on this page.

What are the side effects of Loratadine?

Common side effects of Loratadine (≥ 1 in 100): Headache, Dry mouth, Fatigue (rare). See the Safety section for uncommon and serious reactions.

Is Loratadine safe during pregnancy?

Is Loratadine compatible with breastfeeding?

Passes into breast milk in negligible amounts. Compatible with breastfeeding per LactMed.

Who should not take Loratadine?

Loratadine is contraindicated in: Hypersensitivity to loratadine or desloratadine. Full list in the Safety section.

loratadine for a cold and runny nose

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.

loratadine for any rhinitis, not just allergic

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.

loratadine before a shot to avoid reactions

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 %.

loratadine for eye redness or irritation

in viral or bacterial conjunctivitis, systemic antihistamines do not work. AAO recommends symptomatic treatment for viral and topical antibiotics for bacterial cases.

Official sources

Direct links to regulator labels. Open in a new tab.

AEMPS / CIMALabel dated 06/30/2026
FDA / DailyMedLabel dated 03/31/2026

Other drugs in this group

Promethazine, Rupatadine, Bilastine, Cetirizine, Chlorpheniramine, Dimenhydrinate, Ebastine, Chloropyramine