There's no point adding stress to your already stressed-out upper respiratory system, and that's what the change in air pressure will do. Flying with cold or flu congestion can temporarily damage your eardrums as a result of pressure changes during takeoff and landing. If you must fly, use a decongestant and carry a nasal spray with you to use just before takeoff and landing. Chewing gum and swallowing frequently can also help relieve pressure.
This natural sweetener may work just as well for a cough as over-the-counter medicines. That could be especially helpful for children who aren’t old enough to take those. But don’t give it to an infant or a toddler younger than 1. There’s a small risk of a rare but serious kind of food poisoning that could be dangerous for them. And while you may have heard that “local” honey can help with allergies, studies don’t back that up.