Viagra will work more quickly when taken on an empty stomach because the active ingredient, sildenafil citrate, will absorb into the bloodstream quicker. Food that is eaten less than two hours before taking Viagra, especially if it is high in fat content, like fries and a cheeseburger, can prevent absorption of the medication and delay its effectiveness. However, the pill can be just as effective when taken with food, once the active ingredient is absorbed.

It is recommended not to take alcohol with ED medications such as Viagra because it can cause an increase in side effects such as headache or muscle aches. However, the official patient information for ED medications warns only not to drink "in excess" while taking them, which it defines as five or more drinks.