I have a skin peel kit that is 5 years old. Can I still use it?

Glycolic acid can lose potency with time or can gain potency if the solution has evaporated leaving behind the residue. I would opt for a non-expired version. Best, Dr. Karamanoukian Los Angeles

Without doubt, after five years on the shelf I would throw out any physical product you have on hand. Unless it has an expiration date that states otherwise, you should presume that it is expired. Most medical products (as a general statement) have a shelf life of 1-2 years. Five years would be extraordinary. Replacing this item with a safer current version is a great idea and the only reasonable option. Thank you for the great question! Best! Doc L.

Thank you for your
question.It is not recommended to use any expired products, especially peels that may contain active ingredients. 

To be sure, see two
or more board-certified providers in your area for a complete evaluation to
make sure you are a good candidate and that it is safe for you to have
treatment.

I hope this helps.