Chemical exfoliants like Glycolic Acid are great for treating a wide range of skin complaints from acne to hyperpigmentation thanks to their ability to remove dead and damaged cells from the surface of the skin. The first time you use an AHA based product it is common to feel a slight tingling or mild stinging sensation which can feel odd but is a completely normal reaction.
This happens because the low pH of the acid triggers a response from the skin, as it is encouraged to increase the production of collagen which is why you can feel it working on the skin for a few seconds before it subsides. After a couple of uses your skin won’t react at all but this doesn’t mean it isn’t working, your skin has simply become used to the ingredient. If your skin feels itchy, irritated or very sore afterwards you should stop using the product immediately as your skin may be too sensitive to benefit from a chemical exfoliator.