Take a quick stroll through pharmacy aisles in the U.S. and you'll likely see melatonin supplements in many forms—from fast-dissolve tablets to sweet gummies. Most Americans won't find this unusual, but it's sure to raise a few eyebrows among health experts coming from abroad, like Cliona Byrnes, R.D., a registered dietitian nutritionist who previously worked in Dublin.
"In Ireland, you can't buy melatonin on a shelf or online. It has to be prescribed by a doctor," Byrnes explains. After taking the client's needs and health history into account, she adds, most doctors only prescribe it for short-term use. If you try to order melatonin supplements online, you risk getting them confiscated by customs. And this isn't just Ireland being needlessly strict; most countries outside of the U.S. and Canada require a prescription for the sleep aid.