Glycolic acidThis is used for superficial peels. They are very safe and effective even at high concentrations. It also has a very long shelf life compared to the other acids.
One of the downsides to using glycolic acid is that it has a tendency to penetrate the unevenly. This also has to be neutralized after use.
Trichloroacetic acidThis type of peeling agent has a wide range of concentration spanning from superficial to deep. Frosting comes quickly to the skin once applied so it is easy to evenly distribute. There's no need to neutralize the acid after treatment.
At a higher concentration, scarring and hyperpigmentation can occur.
TCA also has a limited shelf life. Fortunately, it is also relatively one of the most inexpensive on the market.
Salicylic acidThis is a BHA or Beta-hydroxy acid. This means that the agent is small enough to seep into the pores and unclog them, making it highly recommended for acne prone and oily skin.
It is also superficial peeling agent that causes frost, and therefore easy to apply evenly on the skin. It also does not penetrate deeply however, so there is no need to neutralize it after the procedure.
People who are allergic to aspirin and those who are undergoing pregnancy should avoid this type of peel.
Lactic acidA mild type of peel with moisturizing effects. It is therefore recommended for those wanting to address dry and dull skin. This is an AHA or Alpha-hydroxy acid, which means it only penetrates the skin superficially.
This is one of the oldest form of chemical peels, recorded way back in ancient Egypt. Cleopatra used sour milk in her regimen, which we now know contains ample amount of lactic acid.