Follow the manufacturer’s directions to use and clean the oral syringe. Medicines that block an enzyme called CYP3A4. To use the oral liquid: Shake the bottle well for at least 10 seconds before each use. These medicines prevent an enzyme called phosphodiesterase type-5 from working too quickly. It works for up to 36 hours. Read and follow these instructions carefully before you start using sildenafil and each time you get a refill of your medicine. These medicines all work well for ED. · Teva’s version of sildenafil debuted at an average cash price of around $30 per pill, roughly 50% cheaper than brand-name Viagra. Since then, more manufacturers have brought generic versions of Viagra to market, bringing prices down even further. The average retail price of the most common prescription of sildenafil could cost a .  · What is the cost of sildenafil without insurance? The cost of sildenafil without insurance starts at $* for a quantity of 30, 20mg tablets, using a RxSaver coupon. The cost of sildenafil can vary in price depending on the pharmacy your sildenafil prescription is filled at. Below is a list of pharmacies and the starting cost of a sildenafil. Brand Names: Revatio, Viagra Sildenafil is used to treat male sexual function problems (impotence or erectile dysfunction-ED). Learn more about sildenafil oral. 1 Sildenafil is .