The only thing that Vicks does when put on your feet is to help your body cool off when you're feeling hot such as when you have hot flashes or have a fever.
The Vicks on the feet doesn't actually lower your body temperature but it does make your body overall feel cooler so it does help when you have a fever or hot flashes.
But other than that Vicks on your feet doesn't do much but it's also good for your skin and helps prevent the feet from drying out and cracking as well.
Putting Vicks on your feet helps to make you feel cooler especially when you're having hot flashes or a fever.
Although the Vicks doesn't actually make the fever go down or the temperature of the hot flashes go down but applying some Vicks to your feet helps you feel cooler due to the cooling affect it has on the body.
The cooling affect on your body comes from the camphor and menthol in the Vicks but it doesn't do much but it does make you feel cooler at least temporarily which is a good thing.
I add some Vicks to my feet when I'm having a fever or hot flashes and my body does feel cooler at least for a few hours so it's worth it.