If you become pregnant while taking sildenafil, call your doctor. The decision, Teva Canada Ltd. Ask your pharmacist for a list of the ingredients. Often, these are prescribed for chest pain called angina. These medicines are called PDE5 inhibitors. Its effects often last for 4 to 5 hours. New Zealand Sildenafil was reclassified in New Zealand in so it could be bought over the counter from a pharmacist.Viagra – Uses, Side Effects, and More Generic Name (S): sildenafil Uses Sildenafil is used to treat male sexual function problems (impotence or erectile dysfunction-ED). 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. This increased blood flow can cause an erection. Sildenafil treats PAH by relaxing the blood vessels in the lungs to allow blood to flow easily. What is Viagra? Viagra relaxes muscles found in the walls of blood vessels and increases blood flow to particular areas of the body. Viagra is used to treat erectile dysfunction (impotence) in men. Another brand of sildenafil is Revatio, which is used to treat pulmonary arterial hypertension and improve exercise capacity in men and women.