I can atest to the fact that Poseidon does indeed help prevent and cure a hangover. I drank wine last night. A decent amount of both red and white. Usually I can handle the white wine fine but red gives me nasty headaches. However I'm an idiot and I like the taste so once I get a little buzzed I convince myself I won't get a headache or that it's worth it for the taste.
Anyway, before bed I drank a HUGE glass of water with 1 heaping serving Poseidon in it. I woke up this morning feeling pretty decent, much better than in the past and much better than I had inticipated I then had another serving that I'm sipping on this morning and I feel great.
Of course it probably won't prevent a hangover if you get totally blitzed, but it definetly helps, and I've tried almost every homemade/wives' tales hangover "prevention" and "cure" out there.