This site is intended only for U. It is thought that this reduced sales over the Internet and was safer as males could be referred for medical advice if appropriate. New Zealand Sildenafil was reclassified in New Zealand in so it could be bought over the counter from a pharmacist. You are encouraged to report adverse events related to Viatris products by calling U. United States Sildenafil is available as a generic drug in the United States, labeled for pulmonary arterial hypertension. Retrieved 6 October History Sildenafil compound UK, was synthesized by a group of pharmaceutical chemists led by Simon Campbell [55] working at Pfizer’s Sandwich, Kent , research facility in England.Viagra (sildenafil) is a prescription drug that’s used to treat erectile dysfunction (ED). The drug comes as a tablet you’ll take by swallowing. It’s usually taken . Examples of Viagra’s more commonly reported side effects include: headache. flushing (temporary warmth, redness, or deepening of skin color) stuffy nose. .  · How to take Missed dose Overdose Takeaway Drug Images Viagra treats erectile dysfunction (ED) in adults. It’s usually taken about 1 hour before sexual activity. .