GG - there is one way to prevent a hangover - and it will work 100% of the time.........don't drink to start with. Self medicating is dangerous, drinking too much is harmful to your physical health, and mental health, etc etc etc. AND if u are taking any of the medications that you were on in the past - alcohol intensifies those meds, and those meds intensifies the alcohol. Its a total no win situation. As the famous saying goes "Just say NO". Celebrate the 4th in style, without drinking, and feel better tomorrow !