Common side effects of sildenafil can include lightheadedness, dizziness, headache, flushing, fainting, dry mouth, and vision changes. The medication comes in tablets of 25mg, 50mg, and 100mg; however, you should always use the lowest effective dose possible.

Sildenafil used for ED can be taken at a max of once per day. Sildenafil can take between 20 minutes to 1 hour to begin working, and the effects can last up to 6 hours. The medication can be taken with or without food, but if you take it with a high-fat meal, it might take longer to work. Both sildenafil and tadalafil (generic form of Cialis) are effective treatments for ED; however, some people prefer sildenafil because of its faster onset of action.

Sildenafil in the 20mg tablet has the same active ingredient as Viagra, but it goes by the name Revatio. At this dose, it is used to treat pulmonary hypertension or high blood pressure in the lungs in addition to erectile dysfunction.

Make sure to also inform your doctor and/or pharmacist of all other medications (including over-the-counter drugs and supplements) you are taking in order to prevent drug interactions.

You should also speak with your doctor about eating grapefruit or drinking grapefruit juice while taking sildenafil since it is possible the fruit will interfere with the medication.  Lastly, inform your doctor if you are on nitrates, as they cannot be taken together with Sildenafil.

This paragraph is only an overview, and it is not intended to replace medical counseling; please consult your pharmacist and/or medical provider for more comprehensive information.