Inside each milium is a tiny ball of keratin, the same tough protein that makes up your hair and the outer layer of your skin. Unlike a whitehead, which contains oil and bacteria, a milium is a small cyst packed with hardened skin protein trapped just beneath the surface. That’s why milia feel firm to the touch and look like little white or yellowish pearls embedded in the skin.
Keratin: The Core of Every Milium
Keratin is the structural protein your body uses to build skin cells, hair, and nails. Your skin constantly produces new cells and sheds old ones. Normally, dead skin cells flake off the surface without you noticing. But sometimes those cells get trapped in a tiny pocket beneath the outermost layer of skin, where the keratin hardens into a dense, round plug.
This plug sits inside a thin, sac-like wall of skin cells, forming a true miniature cyst. The cyst has no opening to the surface, which is the key reason milia can’t be squeezed out like a regular pimple. There’s no pore connecting the trapped keratin to the outside. The white or pale yellow color you see through the skin is the compressed keratin itself, visible because the cyst sits so close to the surface.
Why Milia Are Not Whiteheads
People often confuse milia with whiteheads, but their contents are fundamentally different. A whitehead (closed comedone) is a follicular plug, meaning it forms inside a hair follicle and contains a mix of sebum (skin oil), dead cells, and bacteria. Because it’s connected to a follicle, a whitehead can often be expressed with gentle pressure.
Milia are non-follicular, subepidermal keratin cysts. They form outside the hair follicle, sitting just under the top layer of skin. The contents are firm and solid rather than soft or oily. That’s why squeezing a milium does nothing productive. The keratin ball won’t budge because it has nowhere to go. Attempting to pick, scratch, or pop milia can cause bleeding, scabbing, scarring, or infection.
How Keratin Gets Trapped
There are two main paths to milia formation, and both end with keratin sealed beneath the skin surface.
Primary milia appear spontaneously, without any obvious trigger. They’re common on the eyelids, forehead, cheeks, and sometimes the genitals. In adults, they likely develop when the skin’s natural exfoliation process stalls in a small area, allowing dead cells to accumulate in a pocket rather than shedding normally. In newborns, milia are extremely common and thought to reflect the immaturity of the skin’s shedding cycle. These typically resolve on their own within a few weeks as the infant’s skin matures.
Secondary milia (sometimes called traumatic milia) form after the skin has been damaged. Burns, blisters, rashes, and excessive sun exposure can all disrupt the normal architecture of the skin, creating small pockets where keratin collects during the healing process. Heavy skincare products can also trigger secondary milia by forming a seal over the skin that traps dead cells underneath. The most common culprits are petrolatum, mineral oil, lanolin, and thick synthetic waxes, particularly when applied around the delicate eye area. Heavy botanical oils used thickly overnight can contribute as well.
Why You Can’t Remove the Contents Yourself
Because the keratin cyst has no connection to a pore, there is no natural exit path. Pressing on a milium just compresses the surrounding skin without releasing anything. The harder you press, the more likely you are to damage the tissue around the cyst, introducing bacteria and risking scarring.
A dermatologist removes milia through a simple procedure sometimes called de-roofing. Using a sterile scalpel or needle, they make a tiny incision in the skin directly over the cyst. Then they lift or press out the small keratin ball using a comedone extractor, a flat blade, or fine surgical forceps. The entire process takes seconds per bump, and because the incision is so small, it heals quickly with minimal scarring. Once the keratin plug is removed, that particular milium won’t come back in the same spot.
Preventing Keratin Buildup
Since the contents of milia are trapped dead skin cells, strategies that promote regular cell turnover can help prevent new ones from forming. Gentle chemical exfoliants containing ingredients like salicylic acid or retinoids encourage the skin to shed dead cells before they have a chance to become trapped. These are especially useful if you tend to develop milia repeatedly.
Choosing lighter, non-occlusive moisturizers is another practical step. If you’re prone to milia around the eyes, avoid heavy creams and ointments in that area. Look for oil-free or gel-based formulas that hydrate without forming a thick barrier over the skin. Sun protection also matters, since UV damage disrupts normal skin turnover and can create the conditions for secondary milia to develop.