There were highly statistically significant improvements on the two principal IIEF questions frequency of successful penetration during sexual activity and maintenance of erections after penetration on VIAGRA compared to placebo. Read more on male sexual health on the Sexual Health Australia site. Cialis and Viagra are equally effective. In pulmonary hypertension it works by relaxing blood vessels in the chest. Sildenafil does not prevent pregnancy or the spread of sexually transmitted diseases such as human immunodeficiency virus HIV.Dosage. The dose of Cialis you need will depend on whether you’re taking it daily or as needed. Daily doses are often between and 5 milligrams (mg). The as-needed dose is usually 10 mg but can range from 5–20 mg. The typicaldose of Viagra is 50 mg. However, the dosage can range from 25– mg. About sildenafil (Viagra) Sildenafil is a medicine used to treat erection problems (erectile dysfunction). Sildenafil is also sometimes used to treat pulmonary hypertension (high blood pressure in the blood vessels that supply the lungs). If you have erection problems sildenafil works by temporarily increasing blood flow to your penis when. Brand-name Viagra is also available through Optum Store in , , mg pills starting at $80 per dose if purchased in bulk. Pros & cons Free online consultation and free shipping on medications.