This results in improvement of erectile function. During pregnancy, sildenafil should be used only when clearly needed. Some of the less common side effects include sudden decrease or loss of hearing, color tinge, increased brightness of light, blurred vision, sudden decrease or permanent loss of vision in one or both eyes, skin reactions such as rashes, blisters, peeling skin, painful erection lasting for more than 4 hours priapism. The drug is metabolized in liver and has a half-life of 4 hours. The generic form of Viagra Sildenafil is available in dosage forms of 25 mg, 50 mg and mg.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 medication Viagra is manufactured by Pfizer Canada Inc and it comes in 25 mg, 50 mg and mg dosage forms in a blister pack of 4 tablets. We are supplying brand Viagra . How to get Viagra in Canada for free? You can get Viagra for free in Canada if your health insurance provider covers it fully. Contact your provider or us to help you find out if you .