Loratadine

How it works

It is a selective peripheral histamine H1-receptor antagonist that blocks histamine-driven allergic symptoms including itch, sneezing, rhinorrhoea, and urticarial weals.

Prescribing in practice

• Dose adjustment is advised in significant hepatic impairment, where clearance is reduced; refer to the SPC and use a children's formulary for paediatric dosing.
• It is generally well tolerated and non-sedating, though occasional drowsiness, headache, and dry mouth can occur.
• Available over the counter for short-term allergy symptom relief as well as on prescription; review current prescribing references for cautions.

Monitoring

Routine monitoring is not required; assess symptom control and tolerability, with caution in hepatic impairment.

Counselling the patient

• This usually relieves allergy symptoms without causing drowsiness, but stop and seek advice if it does affect you.
• It can be taken regularly during periods of allergen exposure such as the pollen season.

Evidence & guidelines

Loratadine and other second-generation antihistamines are recommended first-line for allergic rhinitis and chronic urticaria in NICE and international allergy guidance.