On the Compatibility of Hydroquinone and Glycolic Acid
Hydroquinone and glycolic acid are both agents used in skin care. However, whether the two can be used together, there are different opinions, and it needs to be explored in detail.

Hydroquinone has excellent whitening effect. Its principle is to inhibit the activity of tyrosinase, which is a key enzyme in the process of melanogenesis. Melanin is the main cause of deepening skin color. Hydroquinone can block the synthesis of melanin, so it is often heavy in whitening skin care formulas.

Glycolic acid belongs to the category of α-hydroxy acids. It can loosen the connection between keratinocytes, promote the renewal of the stratum corneum, make the old waste keratin on the surface of the skin fall off, make the skin smoother and more delicate, and can stimulate the synthesis of dermal collagen, improve skin texture and elasticity.

As for whether the two can be used in combination, many factors need to be reviewed. First, consider its chemical properties. Under specific conditions, the two may chemically react, causing changes in active ingredients, affecting the effectiveness of skin care, or even generating harmful substances. Second, observe the tolerance of the skin. Both hydroquinone and glycolic acid are irritating to a certain extent. When used together, the skin is irritated or increased sharply, causing redness, swelling, tingling, itching and other discomforts, especially for sensitive skin.

However, there are also studies showing that if the concentration of the two is appropriate and the formula is reasonably designed, it may be safe to use together. For example, first use low-concentration glycolic acid to condition the skin to make the stratum corneum slightly loose, and then use hydroquinone, which may increase the penetration of hydroquinone and strengthen the whitening effect. However, this operation needs to be done with caution and must be determined according to the individual skin condition.

In general, the compatibility of hydroquinone and glycolic acid should be weighed against the pros and cons. Before trying it, users should consult a professional or try it locally to observe the skin's reaction, so as to ensure the safety and effectiveness of skin care.