Viagra versus Cialis
Cialis VS Viagra: approval dates and duration of action
On March 27, 1998, Viagra became the first oral pill, and the first PDE5 inhibitor, to be approved by the FDA for the treatment of erectile dysfunction (Historical Information on Sildenafil citrate, US Food and Drug Administration, 08/2013) A generic for Viagra was to be available in December 2017.
Cialis was approved for the treatment of sexual impotence on November 21, 2003. (Cialis, Center Watch 2016). It was the third PDE5 inhibitor to come on the market after Levitra (vardenafil). (Doggrell SA, Comparison of clinical trials with sildenafil, vardenafil and tadalafil in erectile dysfunction, Expert Opin Pharmacother, 2005). Cialis has an advantage over Viagra and Levitra in that it lasts much longer: 36 hours compared to 4-5 hours for Viagra and Levitra. However, there is no generic for Cialis.
How fast do Cialis and Viagra work?
Cialis usually works within 16-45 minutes, and its activity is not affected by food. Viagra usually works within 30 minutes, and its effect may be diminished if taken shortly after a high-fat meal. For this reason, Viagra works best when taken on an empty stomach.
The efficacy of all PDE5 inhibitors is similar; although the reported efficacy of Viagra (84%) is slightly higher than that of Cialis (81%), more men prefer Cialis because of its longer duration of effect.
What is the usual dosage of Cialis and Viagra?
Cialis can be taken as needed, or daily. Usually, daily doses are smaller than needed doses. Typically, Cialis is taken at an initial dose of 10 mg before sexual activity. The effects of Cialis will last about 36 hours. The dose may be increased to 20 mg if the 10 mg dose is ineffective or reduced to 5 mg if the side effects are intolerable.
When Cialis is taken on a daily basis, the recommended initial dose is 2.5 mg once daily, or 5 mg for people who also have benign prostatic hyperplasia. It does not matter when the daily dose is taken in people who use it only for erectile dysfunction. However, those with BPH are advised to take it at the same time each day.
Viagra is taken as needed, at a dose of 50 mg, about 1 hour before sexual activity. The dose can be increased to 100mg if the 50mg dose is ineffective or decreased to 25mg if the side effects are intolerable. Viagra should only be taken once a day although the effects wear off after about 4-5 hours.