Do not take a double dose to make up for a missed one. Males between the ages of 30 and 65 would be eligible to buy four tablets after a consultation with a pharmacist. If you ever need emergency medical treatment for a heart problem, the healthcare providers who treat you will need to know when you last took sildenafil. Pfizer Canada Inc. These are commonly prescribed for an enlarged prostate or male pattern baldness.How does Viagra work? Viagra is used to treat erectile dysfunction (ED). It decreases ED symptoms by helping you get and keep an erection. Erections happen when a protein called cyclic. Sildenafil Sildenafil, sold under the brand name Viagra, among others, is a medication used to treat erectile dysfunction and pulmonary arterial hypertension. [4] [8] It is also sometimes used off-label for the treatment of certain symptoms in secondary Raynaud’s phenomenon. [9]. Sildenafil is used to treat male sexual function problems (impotence or erectile dysfunction-ED). In combination with sexual stimulation, sildenafil works by increasing blood flow to the penis to.