Milia form when tiny collections of a tough skin protein called keratin get trapped beneath the surface of the skin, creating small, dome-shaped white or yellowish bumps typically 1 to 2 millimeters wide. Despite their appearance, they aren’t pimples or clogged pores. Under a microscope, they look like miniature cysts with walls made of layered skin cells and a core packed with keratin.
What Happens Inside the Skin
Your skin constantly sheds dead cells from its surface. Normally, old cells flake off and get replaced by new ones underneath. Milia develop when this turnover process goes sideways: instead of shedding outward, keratin-producing cells form a small, enclosed pocket just below the skin’s surface.
Dermatologists once thought milia were simply “retention cysts,” meaning dead skin that got stuck in a duct. Histological studies now show they’re better described as benign keratinizing growths. Each milium has a defined wall of layered skin cells surrounding a dense center of keratin. That wall is what makes them so stubborn. Unlike a whitehead, which sits in an open pore and can drain, a milium is completely sealed off. No amount of squeezing will push the contents out through normal skin channels.
Primary Milia: The Spontaneous Type
Primary milia appear on their own, without any obvious trigger. They originate from the tiny vellus hair follicles (the fine, nearly invisible hairs covering most of your face). Specifically, they sprout from the lower part of the follicle near where the oil gland connects. This is why primary milia cluster around the nose, cheeks, forehead, and eyelids, where vellus hairs and oil glands are densely packed.
Newborns are especially prone. Primary congenital milia are extremely common in infants, appearing as clusters of pinpoint white bumps across the nose and cheeks. They resolve on their own within the first few weeks to months of life as the baby’s skin matures and begins turning over cells more efficiently. No treatment is needed.
In adults, primary milia also appear spontaneously, often around the eyes and on the cheeks. They can persist for months or even years because adult skin doesn’t cycle as quickly as an infant’s.
Secondary Milia: Triggered by Damage
Secondary milia form after something disrupts the skin’s normal structure. When the skin heals from an injury, new cell growth can create pockets where keratin accumulates instead of shedding to the surface. Unlike primary milia, which come from hair follicles, secondary milia more often originate from sweat ducts or other skin structures that get distorted during the healing process.
Known triggers include:
- Burns, including sunburns severe enough to blister
- Blistering skin conditions that separate skin layers
- Dermabrasion or aggressive resurfacing treatments
- Radiotherapy to the skin
- Topical steroid use, particularly long-term application
- Topical 5-fluorouracil, a chemotherapy cream used for precancerous skin lesions
Secondary milia can show up anywhere on the body, not just the face. They tend to appear in clusters at the exact site of the injury, which helps distinguish them from the spontaneous kind.
Heavy Skincare Products and Milia
Certain skincare ingredients are strongly associated with milia formation, particularly around the delicate eye area. Petrolatum, mineral oil, lanolin, and thick synthetic waxes form a physical seal on the skin’s surface. That seal can trap dead cells underneath, giving them no path to shed normally. Heavy botanical oils applied thickly overnight can contribute too.
This doesn’t mean these ingredients are harmful for everyone. On the body or on resilient facial skin, they work fine for most people. The risk goes up when thick, occlusive products are layered over thin skin (like around the eyes) where the follicles and ducts are already small and easily blocked. If you’re prone to milia, switching to lighter formulations in those areas can make a noticeable difference.
How Milia Differ From Other Bumps
Milia are easy to confuse with whiteheads, syringomas, or other small facial bumps. A whitehead (closed comedone) sits inside a pore and contains a mix of oil, dead skin, and bacteria. It’s softer, slightly compressible, and responds to acne treatments. A milium is firmer, more defined, and won’t respond to standard acne products because the keratin is walled off from the surface entirely.
Syringomas are another common lookalike, especially around the eyes. These are small sweat gland growths that tend to be yellowish or skin-toned rather than pearly white. They’re typically slightly larger, more flat-topped, and often appear in symmetrical clusters on both sides of the face. Unlike milia, syringomas don’t contain keratin and won’t resolve with extraction.
Milia en Plaque
A rare variant called milia en plaque involves clusters of milia grouped together on a red, inflamed patch of skin. It most commonly appears behind the ears or around the eyes, though it can develop on the forehead, nose bridge, or jawline. This form predominantly affects women between their 40s and 70s. The underlying inflammation is what distinguishes it from ordinary milia, and it sometimes occurs alongside autoimmune or inflammatory skin conditions.
Why They Don’t Go Away on Their Own
In adults, milia often persist because the cyst wall is self-sustaining. The layered skin cells lining the inside of the pocket continue producing keratin and depositing it into the center, so the bump stays put or even grows slightly over time. Your skin’s normal turnover process can’t reach the trapped material because the cyst is a closed system.
This is also why topical treatments have limited direct effect on existing milia. A retinoid cream (available in concentrations from 0.025% to 0.1% for prescription tretinoin, or up to 0.3% for over-the-counter retinol) speeds up cell turnover across the skin’s surface. That faster turnover can help prevent new milia from forming by keeping dead cells moving outward instead of getting trapped. But it typically won’t dissolve a milium that’s already walled off. Gentle chemical exfoliants containing alpha-hydroxy acids work on a similar principle: they loosen the bonds between surface cells, reducing the chances of a new pocket forming.
How Milia Are Removed
Because a milium is sealed beneath intact skin, removal requires physically opening the cyst. A dermatologist typically makes a tiny nick in the skin’s surface using a sterile needle, scalpel blade, or lancet, then applies gentle pressure with a comedone extractor or curette to pop the keratin plug out. The whole process takes seconds per bump and usually heals without scarring.
For larger or more numerous milia, other options include electrodesiccation (using a small electric current to break down the cyst) and laser therapy. These are less common for isolated bumps but useful when milia cover a larger area or keep recurring in the same spot.
Attempting extraction at home carries a real risk of scarring, infection, or incomplete removal that leads the milium to refill. The skin around the eyes is especially vulnerable to damage from unsterilized tools or excessive pressure.