Ordering herbs and non-prescription medicines

Hi,
I am new to this forum and am really hoping that someone can answer my question. I will be moving to Brunei next year. At present I live in Thailand, and I take some non-prescription products which I order from iHerb in the USA. I have established that they do ship to Brunei but am concerned about customs restrictions and reports I have read on this forum about the post being very slow and unreliable (I worry that my orders would disintegrate in the heat if they had to sit around for three weeks). Anyway, if anyone has imported herbal products or non-prescription medicines, I would really appreciate any information as I do rely on some of these preparations to maintain good health. Thank you in advance.