Combining glycolic acid + salicylic acid + retinol in one evening, or stacking three acid products on top of each other, is common — and almost always counterproductive. Compounded irritation damages the barrier without producing better results.
Why combining acids underperforms
Each acid disrupts the skin surface to deliver its effect. Two acids together disrupt twice as much without doubling the benefit. The barrier compromise that follows triggers inflammation, sometimes worse acne, and longer recovery between routine steps.
What works instead of stacking
Alternate acid types across nights. Monday: AHA. Wednesday: BHA. Friday: retinol. Saturday and Sunday: barrier repair. Different nights for different actives lets each work without compounding stress.
If your routine includes three or more acids in one evening, your skin is probably overstressed. Pull back and alternate.