AHAs (alpha hydroxy acids) like glycolic and lactic acid are water-soluble and work on the skin surface to brighten and smooth texture. BHAs (beta hydroxy acids) like salicylic acid are oil-soluble and penetrate inside pores, making them ideal for acne and oily skin.

For chemical exfoliants, 2-3 times per week is a good starting point. Sensitive skin may only tolerate once per week. Avoid daily exfoliation unless using very low concentrations. Watch for signs of over-exfoliation like redness, peeling, or increased sensitivity.

Using both in the same routine can cause irritation. Instead, alternate nights — glycolic acid one evening, retinol the next. Or use glycolic acid in the morning (with SPF) and retinol at night. Always listen to your skin and reduce frequency if irritation occurs.

Signs include persistent redness, tightness, peeling, burning or stinging when applying products, breakouts, and increased sensitivity. If you notice these, stop all actives, focus on gentle cleanser, ceramide moisturizer, and SPF until the barrier recovers (usually 2-4 weeks).

Chemical exfoliation is generally preferred as it provides more even, controlled results without the risk of micro-tears from scrubs. AHAs and BHAs dissolve bonds between dead cells rather than physically scrubbing them off, resulting in smoother, less irritated skin.