This is about onions, feet and health. How old are these ideas?
When someone gets a cold that lasts for 10 days her friends behave as if nobody has ever had a bad cold before and rally round with advice like “Apply Vicks to your feet”. Applying cures to your feet (quite the wrong end for a cold) goes back to the time of the plague, when you might be advised to apply a pigeon cut in half… Cutting an onion and leaving it on the window to absorb germs (or “miasma”) goes back to the same era. We are told not to leave a cut onion in the fridge as it will "absorb toxins". It's more likely to scent the rest of the food. (In the pandemic, we have fewer colds thanks to masks and constant hand-washing.)
When the Victorians got colds they gave their feet a “mustard bath” – mustard in hot water. They thought colds were caused by wet feet. (At least you'd have warmer feet.)
Doctors point out that many drugs are absorbed through the skin, like nicotine or contraceptive patches, but point out that the soles of your feet are too thickened to absorb much.
In the 30s debutante Monica Dickens went undercover as a servant, and wrote about it in One Pair of Hands. Her fellow-servants liked to complain that their feet would “draw” in wet weather. At school at the convent we swapped a recipe for fainting – put wet blotting paper in your shoes. It didn’t stop you fainting, it made you faint – that was the idea. It was the only way you could get out of the choir rehearsal, or interminable pointless ceremony. A friend once fell through a phalanx of singers standing on a stepped rostrum: she told me later she used to fake it. (We thought colds were caused by wet hair, too.)
I was only one or two years old and had whooping cough. A (what was then called) gypsy came to the door selling clothes pegs, or white heather or something. She heard me whooping and coughing. She advised my mother to put slices of onion in my shoes until my breath smelled of onion, and three days later the cough would go away. And (according to my mum) she did that and the cough departed on schedule. I suppose that it might have gone anyway, or whatever else she was giving me could have been effective. I did not have any say in the matter at that age. (A friend writes.)
More misinformation here, and links to the rest.