No dietary supplements--or drugs, for that matter--are "approved" by the FDA. Problems arise when the FDA believes companies are violating its rules.
The ones I mentioned haven't heard from the FDA. Of them, DRNK's NoHo and RESQWATER say they treat hangovers. Monster's Rehab products are less specific; the company advertises their "rehydrating" effect. Berocca's TV ads say the drink makes you feel more energetic and "sharper".