IRRITATION ON THE BACK OF YOUR FOOT?
Check the upper.
If skin redness occurs on the back of your foot, the problem may be related to the shoe upper. Initially, allergic contact dermatitis on the feet often involves the back of your big toe, the irritation then spreading to the back of the other toes. The discomfort can be caused by either the dyes used in both leather and plastic/rubber shoes or the nickel in metal parts of your footwear, such as sandal buckles or laces with eyelets, or the chromium salts found in the uppers of leather shoes.
It could be the insole.
The sole of your foot is another area that is particularly affected by allergic contact dermatitis: in such case the insole of your shoe is most likely to be blamed, as it may contain chemicals and fragrances that trigger allergic reactions. This is quite a widespread issue among runners, as the friction of their feet against the insoles and foot perspiration create an environment that favours the development of allergens.
ITCHING ON THE SIDE OF YOUR FOOT?
Watch out for glues.
If you feel the itching on the side surface of your shoe, it may be caused by the glues used to attach the sole or insole to the upper. Some neoprene adhesives used in leather shoes contain a major allergen called para-tertiary-butylphenol-formaldehyde resin.
IS THERE A CURE?
The only solution is to change your shoes. Whatever area of your foot is affected by the inflammation, you should always consult an allergist, podiatrist or dermatologist and show them the shoes that are causing you discomfort. A specialist will probably invite you to undergo a patch test to identify the exact allergen you are sensitive to. However, you should be aware that there is no cure for allergic contact dermatitis on your feet. You can only keep it under control by not wearing shoes that trigger irritation and choosing hypo-allergenic footwear, such as R-lief.