Tadalafil is the active component in Vidalista 20 mg. This works similarly to the active ingredient in Viagra, Sildenafil, by relaxing blood vessels and increasing blood flow in the genitals. Vidalista is a Cialis alternative containing the active component tadalafil. Tadalafil normally begins to work in 30 to 60 minutes. Because it is activated by sexual stimulation, you must be aroused for it to work if you use it to treat erectile dysfunction.