A milium is a small keratin-filled cyst sitting in the superficial dermis. It presents as a firm white or yellowish domed papule, typically 1 to 2 mm across, most often around the eyes and on the cheeks. Histologically it is identical to an epidermoid cyst — a complete epithelial lining with a granular cell layer, filled with lamellated keratin — simply far smaller.
Key Facts
- 1–2 mm — the typical diameter of a milium, presenting as a firm white or yellowish domed papule
- Subepidermal — milia sit in the superficial dermis, beneath the epidermis, rather than opening onto the surface like a comedone
- Complete epithelial lining — each cyst has its own full lining with a granular cell layer, containing lamellated keratin — histologically identical to an epidermoid cyst, only much smaller
- Primary vs secondary — primary milia arise spontaneously; secondary milia follow trauma, burns, blistering disorders, cosmetic procedures or certain medications
- Periorbital — the most common site in children and adults, particularly the eyelids and cheeks
- ~50% — the share of full-term newborns showing milia, which typically resolve without scarring within a month of life
- Vellus hair follicles and eccrine ducts — the structures milia arise from — the sebaceous hair collar in primary milia, and sweat ducts in milia following blistering
- De-roofing — the mechanical step that actually empties a milium: opening the cyst with a sterile blade or needle before expressing the contents
The difference that explains everything else
A closed comedone is a plugged follicle. It has a channel to the surface, which is why extraction works and why agents that regulate follicular keratinisation help. A milium has no such channel. It is a sealed cyst under the epidermis, and nothing connects its contents to the outside.
That single fact accounts for the entire experience people describe: the exfoliants that did nothing, the acne treatments that did nothing, the extraction attempts that produced redness and no result. None of those approaches were applied badly. They were applied to the wrong structure.
A milium is a sealed cyst with no opening to the surface. Squeezing it harder is not persistence, it is a misunderstanding of the anatomy — and the trauma that follows is one of the recognised ways new milia are made.
Primary and secondary
Primary milia appear spontaneously, arising in the undifferentiated sebaceous hair collar around vellus hair follicles. They are extremely common in newborns — present in roughly half of full-term infants — and usually resolve without scarring within a month. In children and adults they typically arise around the eye.
Secondary milia follow injury: burns including sunburn, dermabrasion, blistering disorders, cosmetic procedures, and certain medications, with topical steroids well recognised and oral retinoid acne medication documented in occasional case reports. Milia following blistering are often found in eccrine sweat ducts rather than hair follicles. Primary and secondary milia look identical under the microscope; only the history separates them.
This matters practically. Milia appearing after a resurfacing procedure are a known outcome of the healing process, not evidence that something went wrong — a distinction worth understanding alongside the healing profile of ablative treatments discussed in our mole removal article.
How they are actually cleared
The mechanical answer is de-roofing: opening the cyst with a sterile blade or fine needle, then expressing the keratin. Electrodesiccation, curettage, cryotherapy and ablative laser are all described, and topical retinoids are used where lesions are widespread. Every one of these works by creating the opening that the anatomy does not provide.
Around the eyelids, where milia most often sit, the skin is thin and the margin for error is small. That is the reason this is a clinic procedure rather than a bathroom one — not because the individual lesion is complicated, but because of where it usually is.
When more than removal is warranted
A small proportion of primary milia occur in association with rare inherited skin disorders. Multiple eruptive milia — crops developing suddenly over weeks to months — and milia en plaque, an inflammatory variant, both sit outside the routine picture. In older children particularly, milia may be associated with an underlying inherited condition or follow skin trauma, and the sensible response is to establish which before treating.
What they are commonly confused with
Beyond closed comedones, several things present as small pale facial papules: sebaceous hyperplasia, which is usually slightly yellower with a central dimple; syringomas, which cluster under the eyes and are skin-coloured; and xanthelasma, which is flatter, more yellow and sits on the eyelids. Each is managed differently, and treating one as another is the usual reason a course of treatment achieves nothing.
The differential is the practical argument for having them looked at once rather than assuming. A single assessment establishes what is actually there, and whether a series of appointments is even warranted — the same reasoning that applies to skin tags.
What makes them come back
Milia removed properly do not refill at that site. New ones form for the same reasons the first ones did. If the pattern is recurrent in one area, the question is usually what is happening to that skin — occlusive products, a heavy eye cream, persistent sun exposure, ongoing topical steroid use, or repeated trauma from squeezing. Treating the milia without changing the input produces a cycle.
References
- Milia. StatPearls, NCBI Bookshelf. NBK560481
- Idiopathic Multiple Eruptive Milia Occurred in Unusual Sites. Annals of Dermatology, PubMed Central. 2010. PMC2991730
- Milia: Practice Essentials, Epidemiology. Medscape Reference. Medscape
- Gupta M, Oakley A. Milium, milia. DermNet NZ. DermNet
- Milia. UtahDERM Diagnoses, University of Utah. UtahDERM
If milia keep returning in the same area, the reason is usually in what is being done to the skin rather than the milia themselves.
Book My AppointmentFrequently Asked Questions
No, and the difference is anatomical. A closed comedone is a plugged follicle that connects to the surface. A milium is a keratin-filled cyst sitting under the epidermis with a complete epithelial lining and no opening. That is why extraction techniques and acne treatments that work on comedones do not resolve milia.
Because there is nothing to squeeze through. Without an opening, pressure deforms the surrounding skin rather than emptying the cyst. Sustained pressure causes trauma, and trauma is one of the documented causes of secondary milia — so forcing them can produce more.
The cyst is de-roofed with a sterile blade or fine needle so the keratin can be expressed. Other described options include electrodesiccation, curettage, cryotherapy and ablative laser, with topical retinoids used for widespread lesions. The common element is creating an opening that does not exist naturally.
Primary milia arise spontaneously with no identified cause. Secondary milia follow injury to the skin — burns and sunburn, dermabrasion, blistering disorders, cosmetic procedures, and some medications including topical steroids and, rarely, oral retinoid acne medication. Milia after a procedure are a recognised outcome rather than a sign of something going wrong.
In newborns they usually resolve within a month without scarring. In older children and adults primary milia can persist for months or longer. Multiple eruptive milia, or milia in unusual distributions in older children, may warrant a look for an underlying cause rather than only removal.