I usually just take a supply of my usual OTC meds appropriate for the length of stay with me in my shaving kit. I discovered after the first time or two that I had inadvertently violated the law by bringing in pseudophed so switched to the PE version (phenylefren) and simply carry Clariten, Allegra or Coriciden HBP. I may be technically in violation for some of it but have never even been stopped for Customs inspection so do not know.