Sildenafil Oral Jelly 100mg, the active ingredient in Viagra and other similar medications, is used to treat erectile dysfunction. The "stiffness" you're referring to is likely related to the duration of the medication's effects on achieving and maintaining an erection. Typically, Sildenafil starts to work within 30 to 60 minutes after ingestion, and its effects can last for about 4 to 6 hours. However, this doesn’t mean you’ll have an erection for the entire duration.