Is it okay to keep using Dr. Melaxin ampoules?

I was worried because my skin was dull and dark due to freckles on my face. An acquaintance gave me a product called Dr. Melaxin Pico Toning Nickshot Tinting Ampoule, which I have been using. I only use it in the evenings, but after applying it, my skin stings and itches. Could this be an immune reaction? Has anyone used this before? Could you let me know?

I'm wondering if I should keep using it...