In vitro data indicate an inhibition of betahistine metabolism by drugs that inhibit monoamineoxidase (MAO) including MAO subtype B (e.g. selegiline). Caution is recommended when using betahistine and MAO inhibitors (including MAO-B selective) concomitantly. An antagonism between antihistamines could be expected on a theoretical basis. However, no such interactions have been reported.