Milia form when dead skin cells get trapped beneath the surface of your skin instead of shedding normally. Your body constantly produces new skin cells and pushes old ones to the surface, where they flake off. When that process stalls, new skin grows over the old cells, sealing them underneath. The trapped cells harden into tiny keratin-filled cysts, each one appearing as a small, firm white or yellowish bump typically 1 to 2 millimeters across.
These bumps are not pimples, and they won’t respond to squeezing. Understanding what actually causes them helps you figure out whether yours appeared on their own, resulted from something you did to your skin, or signal a deeper issue worth addressing.
What Happens Inside the Skin
Milia originate in the tiny structures surrounding fine body hairs, specifically the lower part of the hair follicle known as the infundibulum. Keratin, the same tough protein that makes up your hair and nails, collects in a small pocket just below the skin’s surface. Once enough keratin accumulates and the opening to the surface is blocked, a cyst forms. Because the cyst sits so close to the top layer of skin, it’s visible as a pearly white dot, but it’s completely enclosed. That’s why milia feel hard to the touch and can’t be popped the way a whitehead can.
Primary Milia: The Spontaneous Kind
Most milia in both children and adults are “primary,” meaning they show up without any obvious trigger. They’re one of the most common reasons people visit a dermatologist, either as their main concern or something they mention during an appointment for something else. Primary milia tend to cluster on the eyelids, forehead, cheeks, and sometimes the genitals.
In newborns, milia are extremely common and considered a normal part of skin development. A baby’s skin is still learning to shed cells efficiently, so tiny keratin cysts form readily on the nose, cheeks, and chin. These almost always disappear on their own within the first few weeks to months of life without any treatment.
In adults, the picture is different. Primary milia can appear at any age and often persist indefinitely. There’s no single reason your skin suddenly traps keratin in one spot and not another. Some people are simply more prone to it, and the bumps may come and go over years.
Secondary Milia: Caused by Skin Damage
When milia appear after an injury or irritation to the skin, they’re classified as secondary. The healing process can disrupt normal cell turnover, trapping keratin beneath newly formed skin. Common triggers include:
- Burns, including sunburns severe enough to blister
- Blistering skin conditions like poison ivy reactions or autoimmune blistering diseases
- Skin resurfacing procedures such as dermabrasion or laser treatments
- Chronic sun damage accumulated over years of UV exposure
- Long-term use of heavy topical creams, particularly potent steroid creams applied to the face
Secondary milia appear directly in the area that was damaged or treated. If you notice small white bumps popping up along a healing scar, in a patch of skin that blistered, or in an area where you’ve been applying a thick cream for weeks, that’s the likely explanation.
Skincare Products That Contribute
Heavy, occlusive products are a frequently overlooked cause. Thick moisturizers, ointments, and some sunscreens can form a seal over the skin that prevents dead cells from shedding normally. The ingredients most associated with this problem include mineral oil and its variants: liquid paraffin, liquid petroleum, paraffinum liquidum, and petrolatum in liquid form. These are used as emollients in many products because they lock in moisture effectively, but their heavy, greasy texture can trap debris in pores and follicles.
This doesn’t mean every rich moisturizer will cause milia. But if you’re prone to these bumps, switching to lighter, non-comedogenic products, especially around the eyes and cheeks, can make a noticeable difference. Eye creams are a particularly common culprit because the skin around the eyes is thin and milia-prone to begin with.
Sun Exposure and Long-Term Skin Changes
Chronic sun damage thickens the outer layer of skin over time, a process that makes it harder for dead cells to reach the surface and shed. Years of unprotected UV exposure can leave your skin less efficient at cell turnover, creating conditions where keratin gets trapped more easily. Milia that develop in sun-damaged areas, often on the temples, cheeks, or forearms, tend to appear in clusters and may recur even after removal.
Genetic Conditions Linked to Milia
For most people, milia are a minor cosmetic nuisance with no deeper medical significance. In rare cases, though, widespread or persistent milia can be a feature of an inherited condition. Several genetic disorders include milia as a characteristic sign, often alongside other skin findings like hair thinning, unusual pitting on the palms, or susceptibility to skin cancers. If you’ve had extensive milia since childhood, especially in unusual locations like the scalp, elbows, or backs of the hands, it may be worth mentioning to a dermatologist who can evaluate whether an underlying condition is involved.
Why You Can’t Pop Them
Unlike a pimple, which has an opening (even a microscopic one) connecting it to the skin’s surface, a milium is a fully enclosed cyst with no pore or duct leading out. Squeezing does nothing except irritate the surrounding skin, potentially causing redness, scarring, or infection. The keratin plug inside is solid, not liquid, so there’s nothing to express.
Dermatologists typically remove milia by making a tiny nick in the skin’s surface with a sterile needle or small blade, then gently extracting the cyst. It’s a quick, low-pain procedure that usually doesn’t leave a mark. For multiple milia, some providers use chemical peels or cryotherapy to address several bumps at once.
Preventing New Milia From Forming
Since milia result from sluggish cell turnover, the most effective prevention strategy is regular exfoliation. Chemical exfoliants work better than physical scrubs for this purpose because they dissolve the bonds holding dead cells together rather than just buffing the surface. Look for cleansers or leave-on treatments containing salicylic acid, glycolic acid, or citric acid. These ingredients help keep pores clear and encourage steady shedding of the outermost skin layer.
Retinol and prescription-strength retinoids are particularly effective because they speed up cell turnover from deeper within the skin. Vitamin A derivatives prompt your skin to push new cells to the surface faster, which prevents the buildup that leads to trapped keratin. If you’re new to retinol, start with every other night to let your skin adjust, as it can cause dryness and peeling initially.
Beyond active ingredients, a few practical habits help. Use lightweight, non-comedogenic moisturizers and sunscreens, especially on your face. Protect your skin from excessive sun exposure, which thickens the outer skin layer over time. And avoid picking at or aggressively scrubbing existing milia, which only damages the surrounding skin without addressing the cyst underneath.