Isothipendyl is a 1st generation H₁ antagonist (antihistamine) and anticholinergic used as an antipruritic. In the 2020s, at least, it is rarely used in the first line relief of allergies due to the anticholinergic side effect of somnolence but does have some limited use through topical application in the relief of insect bites and related itching (pruritus).^{[citation needed]}