Upvote:3
Metamizole is a non-steroidal anti-inflammatory that has no narcotic qualities. It has, however, been banned in the USA and other countries due to possible side-effects that can damage bone marrow.
Ideally, you should just use a replacement NSAID such as acetaminophen, ibuprofen, or naproxen sodium which are all over the counter in the USA.
If you do want to bring it in, it’s not a scheduled drug so it’s unlikely to get you in criminal trouble but you should still declare it. It’ll help if you have a prescription or a physycian’s note as to why you need to use metamizole over any other common replacements, and for you to only bring in an amount that would be reasonable for personal use for the period of time you’re visiting. You should also keep it in its original factory sealed packaging.
If you declare it and customs has a problem, the worst case is that they will confiscate it and let you through without it. If you don’t declare then the worst case is that you get arrested for drug smuggling. So on balance, you should (if you insist on bringing it) declare it.