I use Viagra 100ml. Yes, the heartburn couple of hours after is bloody awful!! ( and the next day ). I have also tried Sildenafil, Cialis, and Levitra, but the heartburn still returns. A way to combat this is, not eat for at least 8 hours before taking it. Take a "Pantoloc tablet" ( available over the counter at chemist ) earlier on, and have a supply of Zantac or Gaviscon on hand. All this agro just to have a good shag!!