Does Trichloroacetic Acid Expire?

Trichloroacetic Acid (TCA) does have an expiration date which should be on the bottle but could be also found with the manufacturer. 50% is a very strong concentration of TCA and should be used only under the supervision of an appropriately trained physician.

Technically any topical should have an expiration date because compounds and catalysts can change over extended amounts of time. If you want specifics on when something that was specially compounded expires, you would need to contact the company that made it.. That being said, if it's nearly 5 years old, I'd say it should be tossed. It's not worth the risk of applying something that might have changed, settled, etc. over the years.