I think time is the only thing that really helps a hangover. When all these other remedies are properly tested, I reckon they won't work better than a placebo.
http://en.wikipedia.org/wiki/Hangover
Within the limited amount of serious study on the subject, there is debate about whether a hangover might be prevented or at least mitigated; additionally, there is a vast body of folk medicine and simple quackery. There is currently no empirically proven mechanism for prevention except reducing the amount of ethanol consumed, or for making oneself sober other than waiting for the body to metabolize ingested alcohol, which occurs via oxidation through the liver before alcohol leaves the body. A four-page literature review in the British Medical Journal concludes: "No compelling evidence exists to suggest that any conventional or complementary intervention is effective for preventing or treating alcohol hangover. The most effective way to avoid the symptoms of alcohol induced hangover is to avoid drinking.
"[20]
Interventions for preventing or treating alcohol hangover: systematic review of randomised controlled trials
http://www.bmj.com/content/331/7531/1515.full