Retinol May Thin Your Skin, but That's Why It Works

New York Times

18-07-2025

Retinoids initially thin out the very top layer of the epidermis (called the stratum corneum). NYT Wirecutter
Skin is made of several layers: From the outside in, they're the epidermis, the dermis, and the hypodermis or subcutaneous fat. The outermost layer, the epidermis, is itself composed of several stacked components. Sitting on the very outside of that top layer is the stratum corneum — and when we talk about 'thinning out the skin,' this is the layer we're talking about.
By the time the cells reach this layer, they've lost their nucleus and are essentially dead, said dermatologist Muneeb Shah. So having a 'thick' stratum corneum isn't always a good thing, as the buildup of dead skin cells can make the skin appear dull. Your skin sheds the dead cells on its own, but using a retinoid (or exfoliant) speeds up the shedding of that dead layer to reveal newer, brighter skin.
So yes, a retinoid thins out this topmost layer initially — but that's a good thing. 'This can be beneficial because it can improve skin texture and tone, reduce clogged pores and acne, and allow other ingredients to penetrate more effectively,' said dermatologist Chelsea Hoffman.
This thinning is temporary because by about four weeks of consistent retinoid use, the fibroblasts in the dermis are producing more collagen and elastin, ultimately thickening the dermis and skin overall, said dermatologist Fatima Fahs. However, that very top layer of dead skin cells 'remains thinner than it would be without retinoid use,' Fahs said, because skin cells are in a constant state of turnover. So whether the thinning is temporary depends on how you look at it, but the good news is, this thinning is working to reveal brighter, smoother skin, Fahs said.
This initial thinning can contribute to 'retinization' — the irritation, skin flaking, breakouts, and redness that crop up for some people when they start to use retinoids. Folks online sometimes refer to it as the 'retinol uglies' or 'purging.' Rest assured that these are normal and temporary side effects for most people (because skin often builds up a tolerance to retinoids after six to eight weeks), and using face moisturizer may help to alleviate some of them. Part of the reaction, such as flaking, can be attributed to those dead skin cells shedding at a quicker rate.