It is in the US. In my brief research I haven&#x27;t found much in the way of negative effects. So, I would expect it to be pretty common.  My only notes are that for sleeping, the dissolve under the tounge tablets work better than regular swallow pills. And, you don&#x27;t need more than 1-2mg. I see 5mg doses sometimes. Don&#x27;t know who needs those.<p>Never thought it would be good for hangovers though. I hangover easily, so I&#x27;ve had lots of opportunities to research treatments.  My current routine is pepto&amp;antacid for nausea (because not much point in taking other stuff if it won&#x27;t stay down).  Then water, NSAIDs (hangovers have lots of cold-like effects) and salt for the bulk effects (bonus points for potassium).  Then get up and get moving and breathing to help your liver oxidize. Then sugar (lost with the salts during urination), b-vitamins (will also be low) and grease (unclog your gall bladder).<p>I have melatonin lying around. I&#x27;ll have to test adding it to the routine next time I have too much fun and forget to stay hydrated.