I used these only once. They started fine and adhere great.
After less than an hour they began to become annoying and irritating even though they were applied to the thick and rough skin on my heels. They didn't cause a reaction or anything as I removed them within an hour although instructions say 6-8 hours.
The smell of vinegar was overwhelming but I did notice a black ring on the outside edges of the patches which are supposed to turn black when the toxins are removed.
Unclear as to whether or not they work but the heel is the roughest part of the body's skin and these are actually indicated for use on ANY NON SENSITIVE AREA of the body..glad I chose my heel to test.
I also was not aware of the minerals inside, ie., copper, magnesium, etc until I received and read the ingredients and instructions. It's like adhering a bag of rocks to your feet.
I personally think the black is a mere reaction of the salt in the skin, the vinegar and the minerals...
Unfortunately, I won't be using the others in the pack or purchasing more.