The present disclosure is directed to chemically-stable and pharmaceutically acceptable sildenafil (1-[[3-(6,7-dihydro-1-methyl-7-oxo-3-propyloral-1H-pyrazolo[4,3-d] pyrimidin-5-yl)-4-ethoxyphenyl]sulfonyl]-4-methylpiperazine) spray formulations for the treatment of diseases such as pulmonary arterial hypertension and/or SSRI-induced sexual dysfunction, wherein the oral spray formulation has a pH of about 1.5 to less than 2.4. The present disclosure is also directed to methods for treating diseases such as pulmonary arterial hypertension and/or SSRI-induced sexual dysfunction.
