Desloratadine
H1 antihistamines
H1 antihistamines
The active metabolite of loratadine, a once-daily non-sedating antihistamine for allergic rhinitis and chronic hives.
Quick facts
- Group
- H1 antihistamines
- Target
- Histamine H1 receptor
- Used for
- Allergic rhinitis · Chronic idiopathic urticaria
- Key effects
- Headache · Mild drowsiness or tiredness · Dry mouth
- Monitor
- Symptom relief
- ATC
- R06AX27
No doses: the clinician sets them by the current guideline.
Mechanism of action
The figure shows desloratadine bound to the human histamine H1 receptor (cryo-electron microscopy).
Desloratadine is the main active metabolite of loratadine, given directly. It is a long-acting peripheral H1 inverse agonist that does not need liver activation and causes little sedation. Some people are slow metabolisers of desloratadine and have higher levels, usually without more side effects.
- Desloratadine is absorbed already in its active form
- It binds peripheral H1 receptors and keeps them inactive
- Sneezing, itch and wheals are reduced
- It barely enters the brain
Indications
- Allergic rhinitis Allergic rhinitis →
- Chronic idiopathic urticaria Urticaria and angioedema →
Adverse effects
Common
- Headache
- Mild drowsiness or tiredness in some people
- Dry mouth
Contraindications
- Hypersensitivity to desloratadine or loratadine
- Caution in liver or kidney impairment
Key interactions
- Ketoconazole, erythromycin
- Raise levels without clinically relevant changes in studies
- Alcohol, benzodiazepines, opioids and other CNS depressants
- Additive sedation and slowed breathing
What is monitored
- Symptom relief
Administration and safety
- Oral tablets, orally disintegrating tablets or solution, once a day
- Not combined with loratadine: it is the same active substance
Pregnancy and breastfeeding
Human pregnancy data are limited; loratadine, which has more data, is often preferred.
Nursing care
- Check that the patient is not also taking loratadine
- Teach that drowsiness is uncommon but possible
Pharmacokinetics
- Absorption
- Well absorbed by mouth, with or without food
- Metabolism
- Liver to 3-hydroxydesloratadine; some people are slow metabolisers
- Elimination
- Urine and faeces
- Onset and duration
- Within about an hour, lasting about a day
Test yourself
Think of the answer, then tap the question to see it.
What is the relationship between desloratadine and loratadine?
Desloratadine is the main active metabolite of loratadine.
Does desloratadine need liver activation to work?
No; it is already the active form.
What are two indications of desloratadine?
Allergic rhinitis and chronic idiopathic urticaria.
Connections
← Back to the class: H1 antihistamines
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - DESLORATADINE tablet, film coated (DailyMed (U.S. National Library of Medicine), 2026); Desloratadine: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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Representative model, for educational purposes only.