Why does milia form?

What gets trapped under the skin?

Skin normally sheds old cells as new ones replace them. When old cells remain trapped beneath new skin, their keratin collects into a small cyst. Primary milia originate in the upper part of a follicle containing a fine hair. Secondary milia can originate in hair follicles, oil ducts, sweat ducts or the outer skin during repair. The white bump is retained skin material, not a whitehead filled with oil.34

Milia commonly appear on the eyelids, cheeks, forehead and nose, although they can occur elsewhere. One cyst is called a milium and several are called milia, because even the smallest skincare topic arrives with vocabulary homework.3

What can trigger milia?

• Primary milia occur in children and adults without needing a preceding skin injury.
• Secondary milia can follow burns, blistering rashes, sun damage or procedures such as dermabrasion, which removes the skin's surface.
• Heavy skin creams or ointments can trigger secondary milia in some cases.
• Long term use of steroid creams or ointments and certain other medicines can be associated with milia.
• Less commonly, milia occur alongside inherited conditions or other skin diseases.

For example, milia can appear as blisters from epidermolysis bullosa acquisita, a rare blistering disease, heal. That is a specific secondary cause, separate from ordinary primary milia. The timing matters: tell your doctor if bumps appeared after blistering, an injury, a skin procedure or a new medicine. Use prescribed steroid treatment only for the duration your clinician directs.35

Why do newborns get milia?

Newborn milia also involve trapped keratin and affect roughly half of babies. They are often present at birth, especially around the nose, and usually disappear within a few weeks without treatment or lasting effects. Milia are also called 'milk spots', a nickname rather than a feeding instruction. They are not baby acne, which causes a different pattern of bumps and usually appears later.136

Can you prevent milia?

There is no reliable way to prevent most milia, particularly newborn milia. For types that follow skin damage, avoid further injury and excessive sun exposure. Use sunscreen outdoors. Heavy facial creams are a possible trigger, not an explanation for every case; milia alone do not identify which product caused them. Adults can discuss exfoliation with a clinician, but newborn milia do not need exfoliating treatments or adult lotions and oils.236

What should you do about existing milia?

Milia are harmless and do not need removal. Adult milia can clear within weeks, but some persist for months or longer. Wash gently each day and pat the skin dry. Do not squeeze, scrape or puncture the bumps yourself: this can cause infection or permanent scarring. If removal matters to you, a clinician can open the cyst with a sterile instrument and remove its contents. Topical retinoids, medicines related to vitamin A, can help with widespread milia; discuss treatment rather than choosing an acne medicine solely because the bumps look white.123

When should you get the bumps checked?

Arrange a medical assessment if the bumps worsen, bother you or have not improved after a few months. A clinician can usually identify milia by examining the skin, although other bumps can resemble them. For a newborn, seek advice if a coloured rash or crusting develops around the bumps. Typical milia are not painful; some less common forms can be itchy or appear together on a raised patch.136