This increased blood flow can cause an erection. Other uses for this medicine This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information. Sildenafil is also sometimes used to treat pulmonary hypertension high blood pressure in the blood vessels that supply the lungs. A stronger CYP3A4 inhibitor such as ketoconazole or itraconazole could be expected to have greater effect than that seen with saquinavir. What special precautions should I follow? Do not take a double dose to make up for a missed one. The information provided is for educational purposes only and is not intended to replace discussions with a healthcare provider.What Happened When I Took Viagra Recreationally. 1. Viagra was effective for much longer than four hours. Shutterstock. Viagra comes in three different sizes: 25mg, 50mg, or mg. In the past, I’ve found that 25mg always did the job just fine. However, my journey begins with a bottle of the mg tabs which I’ve chosen to cut into thirds. 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. Sildenafil citrate is a white to off-white crystalline powder with a solubility of mg/mL in water and a molecular weight of VIAGRA is formulated as blue, film-coated rounded-diamond-shaped tablets equivalent to 25 mg, 50 mg and mg of sildenafil for oral administration.