Treatment of erectile dysfunction in adult males.In order for tadalafil to be effective for the treatment of erectile dysfunction, sexual stimulation is required.It is indicated in adults for the treatment of pulmonary arterial hypertension (PAH) classified as WHO functional class II and III, to improve exercise capacity (see section 5.1).Efficacy has been shown in idiopathic PAH (IPAH) and in PAH related to collagen vascular disease.