Chaser, a capsule made by Living Essentials, is meant to eliminate hangovers by absorbing congeners, generally harmful chemicals produced during fermentation. It contains activated calcium carbonate and vegetable carbon. Both ingredients are recognized as safe by the FDA, and the latter works similar to the activated charcoal often used to treat alcohol poisoning. Chaser is not FDA approved, but the company does assure that its all-natural constitution leaves no side effects.
The actual efficacy of the product is not a proven thing, especially given that congeners are not recognized as the only source of hangovers. Living Essentials backs itself with clinical studies that claim Chaser to be a convenient ten times more effective than a placebo. Many medical professionals, however, would call it just that. Says Dr. Frank McGeorge, an emergency room doctor, "it seems as though they're more than likely trying to absorb or get any toxins to stick to them within your intestines ... it's my opinion these agents would not be very effective for a hangover."
Additionally, Chaser raises an ethical concern; it would seem to be advocating drinking heavily and to excess. Living Essentials is quick to dismiss the issue. "Chaser is not about over-indulging or drinking beyond what you're capable of. We just want people to be able to drink without a hangover the next day," says Carl Sperber, a company official. No shit. The next day.
Regardless, the product itself is simple: Take two caplets when you start drinking and then another pair every two to three hours. Chaser does not prevent dehydration or intoxication, and the product is clear to encourage drinking non-alcoholic fluids and warn against driving.
Chaser also happens to have a commercial with some of the best dialog ever:
Man: I am so hung over.
Woman: And you've got to go to work in an hour!
Man: Why are you feeling so good? You drank more than I did.
Yes, that's how it opens.
Sources:
"Chaser Could Prevent Hangovers", http://www.clickondetroit.com/health/1863532/detail.html
Official Chaser site, http://www.doublechaser.com/NewChaser/News.htm