Oral antihistamines
The less-sedating oral antihistamines are effective for most symptoms of allergic rhinitis, including sneezing, rhinorrhoea, ocular symptoms and itch (including at sites other than the nose, such as conjunctiva, palate and skin). They are less effective than intranasal antihistamines or intranasal corticosteroids for nasal obstruction.
Oral antihistamines have a fast onset of action, so can be used as required for intermittent symptoms; for persistent symptoms, they should be used regularly.
Currently available less-sedating antihistamines appear to be equally effective, but response can vary between patients. Consider trialling an alternative oral antihistamine if response is inadequate.
For an adult, use:
1 cetirizine 10 mg orally, daily1 allergic rhinitis cetirizine
OR
1 desloratadine 5 mg orally, daily allergic rhinitis desloratadine
OR
1 fexofenadine 120 to 180 mg orally, daily as a single dose or in divided doses allergic rhinitis fexofenadine
OR
1 loratadine 10 mg orally, daily. allergic rhinitis loratadine
For a child, use:
1 cetirizine orally1 allergic rhinitis cetirizine
child 1 to 2 years: 0.25 mg/kg (up to 2.5 mg) twice daily
child 2 to 5 years: 5 mg daily as a single dose or in divided doses
child 6 years or older: 10 mg daily as a single dose or in divided doses
OR
1 desloratadine orally allergic rhinitis desloratadine
child 1 to 5 years: 1.25 mg once daily
child 6 to 11 years: 2.5 mg once daily
child 12 years or older: 5 mg once daily
OR
1 fexofenadine orally allergic rhinitis fexofenadine
child 2 to 11 years: 30 mg twice daily
child 12 years or older: 120 to 180 mg daily as a single dose or in divided doses
OR
1 loratadine orally allergic rhinitis loratadine
child 1 to 2 years: 2.5 mg once daily
child 2 years or older, weight 30 kg or less: 5 mg once daily
child 2 years or older, weight more than 30 kg: 10 mg once daily.
Higher doses are unlikely to be of additional benefit, and combining oral and intranasal antihistamine therapy does not confer additional benefit.
Sedating antihistamines are not routinely recommended for treatment of allergic rhinitis, particularly in children, in whom the sedative properties can affect school performance.