Do not mix the liquid with other medications or add anything to flavor the medication. Sorry something went wrong with your subscription Please, try again in a couple of minutes Retry Clinical trials Explore Mayo Clinic studies testing new treatments, interventions and tests as a means to prevent, detect, treat or manage this condition. Before starting, stopping, or changing any medications while taking sildenafil, please get the advice of your doctor or pharmacist. Follow the manufacturer’s directions to use and clean the oral syringe. Visit Mayo Clinic Men’s Health to get started. What’s the best treatment? Please expect up to 4 to 6 weeks for reimbursement.Viagra vs. over-the-counter products. Many over-the-counter (OTC) products may be advertised to help with ED. Examples of these products include: . Sildenafil is in a class of medications called phosphodiesterase (PDE) inhibitors. Sildenafil treats erectile dysfunction by increasing blood flow to the penis during sexual stimulation. . Print Products and services Erectile dysfunction: Viagra and other oral medications By Mayo Clinic Staff Medicines that you take by mouth are called oral .