You can take it up to 4 hours before you want to have sex. The Korean Court system made a ruling against Pfizer in June , allowing for the unhindered domestic production of generic prescription sildenafil. About sildenafil Viagra Sildenafil is a medicine used to treat erection problems erectile dysfunction. That means you can have erections whenever you want or need them. Talk with your healthcare provider about your sex life and desired use. Oral ED medications are generally well-tolerated, Dr. Phosphodiesterase type 5 PDE5 inhibitors.Like most drugs, Viagra may cause mild or serious side effects. The lists below describe some of the more common side effects that Viagra may cause. Viagra vs. over-the-counter products. Many. Size: Women’s. Color: Green. $ USD. $ USD. $ USD. Continue Shopping. Buy Sildenafil with no hidden fees and no prescription required. Generic Viagra is sure to make you regret not turning to our online store earlier. Natural and over-the-counter alternatives for ED. Like Viagra, certain forms of sildenafil are approved to treat ED in males* ages 18 years and older. For example, sildenafil mg, mg, and.