It works thanks to its active ingredient, Sildenafil citrate. This condition causes a sudden, partial decrease or loss of vision in one or both eyes due to damage to the optic nerve. If you have a pre-existing condition such as cardiovascular disorders or liver and kidney problems, you may have issues taking Viagra Connect safely. This double effect means your blood pressure could get too low, which may cause dizziness, fainting, headaches, and even heart palpitations. Check the ingredients listed in the leaflet that comes with the medicine if you know you have specific allergies or intolerances. Viagra is probably the best-known treatment for erectile dysfunction available. Combined with the possible side effects, taking Viagra Connect and alcohol together is unlikely to improve your sexual performance at the same time as being potentially dangerous.Viagra Connect, Viagra and Sildenafil are erectile dysfunction treatments that work within your body to help you achieve and maintain an erection that is hard enough for sexual intercourse. The treatment allows the blood vessels within the body to expand and relax, causing blood to flow to the penis, resulting in an erection. Cialis is only available by prescription in the United States. Viagra: Additionally, a study from Trusted Source. found that combining L-arginine and sildenafil (Viagra) worked better for. Viagra dosage. Most men start by taking one Viagra 50 mg tablet. (This is the strength of over-the-counter Viagra Connect tablets.) Some men will need to start with a lower dose of 25mg prescribed.