Viagra 100mg tablet is a prescription tablet mainly used by men to treat the sexual problem of erectile dysfunction. It is a phosphodiesterase type 5 inhibitor that relaxes and dilates the blood vessels to increase the blood flow in the penis.Good blood flow activates the muscles of the Penis and helps them to fix the erectile dysfunction issues they may be facing. Furthermore, Viagra 100 mg pill also helps in the treatment of pulmonary arterial hypertension (PAH).