When oral medications might not be safe Check with your health care team before you take any medicine for erectile dysfunction. Oral medicines for ED usually work well and cause few side effects. It might work longer if you have mild to moderate erectile dysfunction. Some people may also have ringing in their ears tinnitus or dizziness. Rogue pharmacies are not licensed to sell in the United States and put you at risk of counterfeit or tainted drugs How Many Online Pharmacies Are There? Headache is the most common, and stuffy nose and facial flushing are quite common too. Sometimes Viagra can also cause priapism which is also known as a painful erection.Learn about uses, how it works, and more for Viagra (sildenafil). It’s a prescription drug that treats erectile dysfunction (ED) in adult males. Sildenafil (Viagra). Tadalafil (Cialis). Vardenafil. These medicines are called PDE5 inhibitors. They enhance the effects of a chemical the body makes that relaxes . For further information, call , visit test1.ru, or write: Viatris Inc., P.O. Box , Mission, KS See risks & benefits. Learn more about what VIAGRA® .