Milia

What are milia?

A milium is a small, raised bump on the skin. It is a type of tiny skin cyst filled with a protein called keratin.

Many are usually found together and so they are called milia (the plural of milium).

What do milia look like?

Milia in a newborn

© Serephine, CC0, via Wikimedia Commons

As can be seen in the picture, milia are usually each about 1 or 2 millimetres across and are pearly-white or yellowish. They appear to be small white bumps on the face.

They are most often seen on the skin around the cheeks, nose, eyes and eyelids, forehead and chest but they can occur anywhere on the body.

Types and causes of milia

There are different types of milia.

Neonatal milia

These are milia that are seen in young babies soon after they are born. They are very common and are usually found around the nose area but may also occur on the scalp, cheeks, upper body and inside the mouth. They are thought to arise from sweat glands that aren't fully developed or mature. Around half of all babies develop neonatal milia. In fact, because they are so common, they are actually considered as normal in newborn babies - often they are called "milk spots" although they are nothing to do with milk. They usually disappear by 12 weeks of age.

Primary milia

These are milia that can occur in both children and adults. They occur in an area of skin that has otherwise been normal without any previous damage or injury.

Secondary milia

These are milia that develop in an area of skin, anywhere on the body, that has previously been damaged or injured. For example, after a burn or a blistering rash. The milia develop as the skin heals and it is thought that damage to the sweat glands may be an underlying cause. Secondary milia also sometimes develop after some skin creams have been used.

Milia en plaque

Milia of this type are extremely rare. The milia develop on an inflamed, raised patch of skin known as a plaque which may be several centimetres across. The cause of milia en plaque is not fully understood. It usually occurs behind the ears, on an eyelid or on the cheeks or jaw area. This type of milia tends to particularly affect middle-aged women.

Multiple eruptive milia

The milia appear in crops, or patches, of milia that develop over a period of weeks or months. The crops usually appear on the face, the upper arms and the upper trunk. Milia of this type are also extremely rare.

Milia symptoms

Milia do not usually cause any symptoms but,they can occasionally become itchy.

How are milia diagnosed?

Milia are usually diagnosed by their typical appearance and generally no investigations are needed. However, occasionally, if the diagnosis is uncertain or if milia en plaque are suspected, a skin biopsy might be recommended.

During a skin biopsy, a small piece of skin is removed so that it can be examined under a microscope. There are different ways that a skin biopsy can be carried out. For example, by shaving away a small piece of skin or by using a special instrument to punch a tiny hole in the skin.

How long do milia last?

Milia are harmless and, in most cases, they will eventually clear by themselves. In babies, they clear after a few weeks. However, in some people, milia can persist for months or longer. Secondary milia are sometimes permanent.

Milia treatment

Because they normally clear by themselves, milia do not usually need any treatment. However, some people find them unsightly and so opt for treatment to remove milia.

Milia removal

Milia may be removed using a fine needle and then squeezing, or pricking, out the contents. No anaesthetic is needed. However, it is not recommended to squeeze or try to treat milia yourself. This can lead to skin damage and scarring or infection.

If milia become very widespread and persistent, various other treatments may be suggested, usually by a skin specialist (a dermatologist). They include:

• Crioterapia: a type of treatment that freezes skin lesions. Where a patch of skin has changed in appearance, it is known as a skin lesion.

• Tratamiento con láser.

• Dermabrasion: a procedure that removes the topmost layers of the affected skin.

• Chemical peeling: a treatment where a chemical is applied to the face to burn off skin lesions.

In the rare type of milia called milia en plaque, certain creams such as isotretinoína or tretinoin are sometimes suggested as treatment, or the antibiotic tablet, minocycline.

Can milia be prevented?

Most milia cannot be avoided, particularly neonatal milia. The risk of developing secondary milia development can be reduced by avoiding excessive sun exposure, only using steroid creams for the length of time they are prescribed and regularly exfoliating and cleansing the skin to remove dead skin cells.