Milia form when keratin, the protein that makes up your skin, hair, and nails, gets trapped beneath the surface of the skin and hardens into tiny white cysts. In adults, this happens for a range of reasons: sluggish cell turnover, sun damage, skin injuries, heavy skincare products, and certain medications. The bumps are harmless but stubborn, and understanding what’s behind them is the first step toward clearing and preventing them.
How Milia Actually Form
Your skin constantly sheds dead cells to make room for new ones. When that turnover process slows down or gets disrupted, dead cells can become trapped just below the surface instead of flaking away. Over time, this debris of keratin and dead skin clumps together and hardens into a small, firm cyst typically 1 to 2 millimeters across. Unlike a whitehead, a milium has no opening to the surface, which is why you can’t squeeze it out.
Primary Milia: No Obvious Trigger
Primary milia appear spontaneously, without any preceding injury or skin condition. They’re the most common type in adults and tend to show up on the cheeks, around the eyes, and across the forehead. The underlying issue is simply that your skin’s natural exfoliation isn’t keeping pace, so small pockets of keratin accumulate in the uppermost layer of skin.
Some people are genetically more prone to this. A rare hereditary form called multiple eruptive milia runs in families in an autosomal dominant pattern, meaning a parent with the condition has about a 50% chance of passing it on. Cases have been documented across generations, with clusters of milia appearing on the face and upper trunk. Most adults with occasional milia don’t have this inherited form, but if you consistently develop large numbers of them, genetics may play a role.
Secondary Milia: Skin Damage and Injury
Secondary milia, sometimes called traumatic milia, develop after something damages the skin and clogs the tiny ducts beneath its surface. The triggers include burns, blistering rashes, and skin injuries that disrupt the normal architecture of the outer skin layers. As the skin heals, keratin can get rerouted into small pockets instead of shedding normally.
Cosmetic procedures can cause the same thing. Laser resurfacing, dermabrasion, and chemical peels all strip away the top layers of skin. During the healing process, new milia sometimes appear in the treated area. They’re usually temporary, but they can persist for weeks or months if the skin’s recovery is slow.
Sun Damage and Aging Skin
Chronic sun exposure is one of the most common contributors to milia in older adults. UV radiation thickens and toughens the outer layer of skin over time, making it harder for dead cells to shed on schedule. You’ll often see clusters of milia on sun-exposed areas like the cheeks, temples, and nose in people with years of accumulated sun damage. Reducing unprotected sun exposure is one of the clearest ways to lower your risk of developing new milia later in life.
Heavy Skincare Products
Certain skincare ingredients create a physical seal over the skin that can trap dead cells underneath. The main culprits are petrolatum, mineral oil, lanolin, and thick synthetic waxes. Heavy botanical oils applied generously overnight can also contribute, especially around the delicate eye area where the skin is thinnest and most prone to milia.
This doesn’t mean all moisturizers are problematic. The issue is specifically with highly occlusive products, the ones that sit on top of the skin rather than absorbing into it. If you’re noticing milia in the same spots where you apply a thick eye cream or ointment-based product, switching to a lighter, water-based formula is worth trying.
Medications That Trigger Milia
Several medications are linked to milia as a side effect. Long-term use of topical steroids is the best-documented trigger. In one reported case, milia developed after just two weeks of treatment with a high-potency steroid ointment. The steroid appears to alter the skin’s normal shedding process, allowing keratin to accumulate. Other medications associated with secondary milia include certain chemotherapy drugs, the immune-suppressing drug cyclosporine, and penicillamine (used for conditions like Wilson’s disease and rheumatoid arthritis). If milia appear after starting a new medication, it’s worth flagging for your prescriber.
How to Tell Milia From Similar Bumps
Milia are pearly white, dome-shaped, and very small. They feel firm to the touch and don’t have redness or inflammation around them. A few other skin bumps can look similar at first glance:
- Syringomas are small sweat gland growths that cluster around the eyes, much like milia. The key difference is color: syringomas tend to be yellow, translucent, or skin-toned rather than white, and they’re slightly larger (1 to 3 millimeters). They also don’t contain keratin.
- Whiteheads are acne lesions with a thin layer of skin over a clogged pore. Unlike milia, they’re softer, often slightly inflamed, and respond to acne treatments.
- Xanthelasma are yellowish, flat cholesterol deposits that appear on or near the eyelids. They’re larger and flatter than milia and can signal elevated cholesterol levels.
Removal and Prevention
Milia don’t resolve as easily as acne because they’re sealed beneath the skin with no opening. Over-the-counter acne washes and scrubs generally won’t reach them. The most reliable option is professional removal. Cryotherapy, where the bumps are frozen with liquid nitrogen, is the most common clinical procedure. A dermatologist can also use a sterile needle or small blade to make a tiny incision and extract the cyst. Both methods heal quickly and leave minimal scarring.
Topical retinoids (vitamin A derivatives) are the main at-home treatment with evidence behind them. They speed up cell turnover, helping trapped keratin work its way out over time. You apply a retinoid or its gentler over-the-counter form, retinol, once daily to clean, dry skin. Results take weeks, not days. One important caveat: retinoids make your skin significantly more sensitive to UV damage, so daily sunscreen is non-negotiable while using them.
For prevention, the most impactful steps are consistent sun protection, choosing lighter moisturizers and eye creams (especially avoiding petrolatum and lanolin around the eyes), and using a gentle chemical exfoliant to keep cell turnover moving. If you’ve had milia removed professionally, these habits reduce the chance they’ll return in the same spots.