Viagra generally refers to sildenafil, which typically costs $33 to $429 a bottle, depending on the region, manufacturer, and other factors. Sildenafil belongs to a type 5 phosphodiesterase inhibitor. At present, there is no relevant authoritative information specifying how much a bottle of sildenafil costs, and in general, a bottle of sildenafil may cost $33 to $429. However, due to the existence of the region as well as the drug manufacturers, specifications and other factors, so the specific price of a bottle of sildenafil there is a significant individual variability, can not be generalized. It is recommended that the actual local price prevail. Sildenafil is mainly used to treat erectile dysfunction in clinical practice. However, this drug is contraindicated for women and people with severe hepatic impairment and allergy to the product. Some patients may experience adverse reactions such as flushing, palpitations (rapid heartbeat, often accompanied by panic), nasal congestion, and cough after using the drug. Patients must use Sildenafil under the guidance of a doctor, and should never use the drug on their own to avoid discomfort to their health.