Before taking sildenafil, tell your doctor and pharmacist if you are allergic to sildenafil, any other medications, or any of the ingredients in sildenafil tablet or suspension. Also tell your doctor if you or any of your family members have or have ever had an eye disease such as retinitis pigmentosa an inherited eye condition that causes loss of vision or if you have ever had sudden severe vision loss, especially if you were told that the vision loss was caused by a blockage of blood flow to the nerves that help you see. Key facts It usually takes 30 to 60 minutes for sildenafil to work for erectile dysfunction. People who use nitrates in any form or are being treated for pulmonary hypertension should not take sildenafil. Patients should always ask their doctors for medical advice about adverse events.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. Sildenafil under the name Viagra is used to treat erectile dysfunction (impotence) in men. Another brand of sildenafil is Revatio, which is used to treat pulmonary arterial . AdFree & Private Online Consultant with Real Doctors. Reliable E.D. Meds Shipped Discreetly. Save Time & Money with Online Prescription for Viagra, Cialis, Sildenafil and test1.ru has been visited by 10K+ users in the past monthFree Shipping · Discreet Packaging · Real Doctors · Personalized Plan.