Holding your skin together is not a metaphor. There are actual protein structures called desmosomes that physically anchor your skin cells to each other, and understanding how they work explains a lot about why your skin peels, why exfoliants work the way they do, and why overdoing it with acids can wreck your barrier.
Desmosomes are one of those things that nobody talks about in skincare, but they are fundamental to everything your skin cells do. Think of them as rivets connecting the panels of a ship. Each rivet is small, but collectively they keep the whole structure from falling apart.
What Desmosomes Actually Are
Desmosomes are cell-to-cell junctions. Tiny protein complexes that sit on the surface of adjacent skin cells and lock them together. Each desmosome is made up of proteins from three families: cadherins (specifically desmogleins and desmocollins), armadillo proteins (like plakoglobin), and plakins (like desmoplakin).
The cadherins extend outward from each cell and interlock with cadherins from the neighboring cell, like two hands clasping together. Inside the cell, these cadherins connect to the keratin filament network through the armadillo and plakin proteins. This creates a continuous mechanical link from cell to cell throughout the entire epidermis.
The result is a tissue that can withstand stretching, compression, friction, and all the mechanical stress your skin deals with every day. Without desmosomes, your epidermis would literally fall apart at the cellular level.
Why This Matters for Your Barrier
Your skin barrier is not just about lipids and ceramides filling the spaces between cells. The cells themselves need to be physically connected. Desmosomes provide that structural integrity.
In the lower layers of the epidermis, desmosomes are strong and abundant. Cells are tightly bonded because they need to be. These are the layers where new cells are forming and migrating upward. Strong adhesion keeps everything organized.
As cells move toward the surface and transition into the stratum corneum (the outermost layer of dead cells), something changes. The desmosomes gradually weaken. Specific enzymes called proteases start breaking down the desmosomal proteins, loosening the connections between cells. This controlled degradation is what allows dead skin cells to shed naturally. It is called desquamation, and it is a normal, healthy process.
When desquamation works properly, dead cells release from the surface at a steady rate and your skin looks smooth and fresh. When it does not, cells either shed too fast (leaving the barrier thin and vulnerable) or too slow (building up on the surface and causing dullness, rough texture, or clogged pores).
How AHAs Break These Bonds
This is where it gets directly relevant to your skincare routine. Alpha hydroxy acids (glycolic acid, lactic acid, mandelic acid) work by weakening the desmosomal connections between cells in the outer layers of the epidermis. They lower the pH of the skin’s surface, which activates enzymes that break down desmosomal proteins and loosens the “glue” holding dead cells together.
That is literally what exfoliation is at a cellular level. When you apply an AHA, you are not scrubbing cells off. You are chemically dissolving the protein rivets that hold them in place so they release on their own.
This is also why chemical exfoliants are generally gentler than physical scrubs. Physical exfoliation tears cells away regardless of whether they are ready to detach. Chemical exfoliation targets the desmosomal bonds that are already weakened, speeding up a process your skin was already doing.
BHAs (salicylic acid) work differently. They are oil-soluble, so they penetrate into pores and dissolve sebum and debris. But at the surface level, they also contribute to desmosomal loosening, which is why they help with both clogged pores and surface texture.
What Happens When You Overdo Exfoliation
If AHAs break desmosomal bonds, more AHA means more exfoliation, right? Technically yes. Practically, this is where people get into trouble.
Desmosomes in the deeper layers of your epidermis are not meant to be disrupted. They are there to maintain structural integrity. When you over-exfoliate, whether through too-high concentrations, too-frequent application, or layering multiple acids, you start breaking down desmosomal connections that should have stayed intact.
The symptoms are predictable:
- Skin that looks shiny in a bad way (the surface is too thin)
- Increased sensitivity to products that never bothered you before
- Redness that does not resolve
- A tight, uncomfortable feeling even after moisturizing
- Paradoxically, more breakouts (because the compromised barrier lets bacteria in more easily)
You have essentially weakened too many rivets. The ship is not sinking, but it is leaking. Recovery requires stepping back from exfoliants entirely and letting your desmosomes rebuild, which takes about two to four weeks depending on how much damage was done.
Individual Variation Is Real
Not everyone’s desmosomes behave the same way. Genetic factors influence how many desmosomes your cells produce, how quickly desmosomal proteins are made, and how sensitive those proteins are to enzymatic breakdown.
This is one reason why the same glycolic acid concentration works perfectly for one person and destroys another person’s barrier. If your desmosomal bonds are naturally on the weaker side (common in people with eczema-prone or sensitive skin), even a mild AHA can cause excessive cell shedding and barrier disruption.
People with conditions like peeling skin syndrome have genetic mutations affecting corneodesmosin, a protein critical for desmosomal function in the stratum corneum. Their skin sheds excessively because the connections between surface cells are too weak from the start. This is an extreme example, but it illustrates how much desmosomal variation exists across individuals.
On the other end, people with thick, resilient skin that rarely flakes often have robust desmosomal bonds. They can tolerate stronger exfoliants because their cellular connections can handle more disruption before barrier integrity is compromised.
What This Means for Your Routine
Understanding desmosomes does not change what products you use. It changes how you think about using them.
Chemical exfoliants are desmosome-disrupting agents. That is their mechanism. Used correctly, they assist your skin’s natural shedding process. Used excessively, they undermine the structural connections that keep your barrier intact.
Start with low concentrations and infrequent application. Once or twice a week is enough for most people starting out with AHAs. Increase gradually based on how your skin responds, not based on how quickly you want results. If your skin starts showing signs of over-exfoliation, pull back immediately. Desmosomes rebuild, but only if you give them the chance.
And if you have naturally sensitive or eczema-prone skin, consider PHAs (polyhydroxy acids) over AHAs. Their larger molecular size means they cannot penetrate as deeply, so they target only the most superficial desmosomal bonds. Same concept, smaller impact, less risk of going too deep.
Your skin cells are held together by design. The proteins doing that work are specific, organized, and essential. Respect the system, and it works beautifully. Override it, and you pay the price in sensitivity, redness, and a barrier that cannot do its job.