What Are Milia, and Do They Relate to Acne?

Milia Are Harmless Skin Bumps Unrelated to Acne

What Are Milia, and Do They Relate to Acne?

Article Summary

Milia are tiny, harmless bumps that develop on the skin.  

Primary milia form in skin pores, appearing and disappearing without apparent cause in people of all ages. Research has not discovered the true cause or causes of primary milia. 

Secondary milia are rare and almost always develop in sweat ducts as a side effect of particular skin diseases, medications, or traumas. 

While milia and acne can look similar, they are not the same and do not respond to the same treatment. Medical professionals can treat milia with surgical procedures or drug prescriptions.



Milia are tiny, harmless bumps that can affect adults and children and resemble acne but have little connection to acne. The condition responds to certain treatments, but normally goes away without treatment.  

Definition of Milia

“Milia” is the plural for “milium.” A milium is a pale, harmless bump, usually no more than three millimeters across, that forms on the skin. In the Journal of Investigative Dermatology in 1956, Epstein and Kligman described milia as the most common type of benign skin tumors.2

Close-up Graphic of Milia

Medical experts call these bumps “cysts,” and these tiny cysts contain keratin (a skin protein).

Types of Milia

Many types of milia exist, but they usually fall into two categories.

  1. [Common] Primary milia, which occur without any obvious cause and are located inside pores.
  2. [Uncommon] Secondary milia, which develop as a side effect of certain diseases, such as herpes zoster, contact dermatitis, and leishmaniasis, and traumas, including blistering, sun damage, dermabrasion, or medications like corticosteroids, and are located next to sweat ducts.
Primary Milia

Secondary Milia

At What Age Do People Experience Milia?

Milia can affect people at any age, although it affects babies most often.

American Family Physician

According to a 2008 article in American Family Physician, “They occur in up to 50 percent of newborns.”3 This condition, called congenital milia, usually resolves itself within a few months.

What Are the Most Common Forms?

Congenital milia and a form of milia that affects older children and adults for no apparent reason, called benign (harmless) primary milia, are the two most common forms.

Rarer and more severe forms include multiple eruptive milia (MEM), in which so many milia form that doctors can no longer call it benign,4,5 and milia en plaque (MEP), in which the bumps form lesions (breaks in the skin) and plaques (raised patches of skin).6

Development of Milia

Limited information exists on exactly how milia develop, and whether the cells inside milia divide like normal skin cells or like abnormal cells.7 However, scientists have learned more about where in the skin they develop.

Where Do Primary Milia Develop?

Primary milia often occur in the sebaceous glands (oil glands) inside hair follicles (skin pores).

Where Do Secondary Milia Develop?

Secondary milia normally occur next to eccrine ducts (sweat ducts).

Journal of Investigative Dermatology

A study published in the Journal of Investigative Dermatology in 1975 reports that of the 73 biopsy specimens taken from 10 patients with secondary milia, 54 of them had milia connected to eccrine ducts; 2 had milia in skin pores; and the remaining 17 specimens had milia with no connections to skin pores or to eccrine ducts.8

Causes of Milia

What Causes Primary Milia?

Scientists have yet to discover what causes primary milia. Some members of the public speculate that when primary milia occurs in adults, cosmetics may play a role, claiming that ingredients in cosmetics that cause or aggravate acne may also cause or aggravate milia. However, no research studies exist to support this claim.

Primary Milia Types

What Causes Secondary Milia?

Secondary milia are rare and occur as a side effect of certain skin diseases, topical medications, or skin trauma. 

Milia may also occur after skin treatments.

Expand to read details of studies on skin treatments and milia 

Journal of the American Academy of Dermatology (JAAD)

The Journal of the American Academy of Dermatology reported in 2008 that hyaluronic acid, a popular filler for acne scars, causes side effects that include “erythema, edema, bruising, inflammation, delayed reactions, infection, pain, milia or acne, and rare reports of necrosis.” It also stated that possible side effects from laser therapy “may include delayed healing, erythema, milia, acne, edema, hyperpigmentation or hypopigmentation, infection, or scarring.”10

Dermatologic Clinics

A 2001 article in the journal Dermatologic Clinics notes that milia “appear as part of the healing process...after dermabrasion,” although it also found that “saline scrubs immediately postsurgery may minimize [the development of] milia.11


Secondary Milia Types

Milia and Acne

Although milia and acne develop in the skin, they have little to do with each other, mostly because milia has no connection with inflammation or bacteria as acne does.12 However, excessive picking or rubbing of milia can cause inflammation and make milia look like red, inflamed acne. Dermatologists call this red, inflamed milia pseudoacne. Because it is not acne, common acne treatments will not effectively treat it.13

Treatments for Milia

Primary milia usually go away on their own, although some patients with persistent cases ask for professional help to make them heal faster. Fortunately, both primary and secondary milia respond to a number of medical treatments, including:

Common Treatments

  • Medical staff can treat them surgically, with tools such as scalpels or needles.14
  • A six-week course of a topical retinoid drug called tretinoin can eliminate milia.1 Other retinoid drugs, such as tazarotene and adapalene, work similarly to tretinoin. If tretinoin works, then these may work as well.

Less Common Treatments

Journal of Cosmetic and Laser Therapy

A CO2 laser treatment successfully treated four milia patients in a 2010 study reported in the Journal of Cosmetic and Laser Therapy.15

Journal of Cutaneous Medicine and Surgery

One extreme case in the Journal of Cutaneous Medicine and Surgery in 2006 demonstrated more than 80 percent clearing of the patient’s condition in 3 months with a special device used to remove skin cells by drying them out (electrodesiccation).16


The Experts at Acne.org

Our team of medical doctors, biology & chemistry PhDs, and acne experts work hand-in-hand with Dan (Acne.org founder) to provide the most complete information on all things acne. If you find any errors in this article, kindly use this Feedback Form and let us know.


  1. Connelly, T. Eruptive milia and rapid response to topical tretinoin. Arch Dermatol 144, 816–817 (2008).
  2. Epstein, W. & Kligman, A. M. The Pathogenesis of Milia and Benign Tumors of the Skin. J Investig Dermatol 26, 1–11 (1956).
  3. Connor, N. R., McLaughlin, M. R. & Ham, P. Newborn skin: Part I. Common rashes. Am Fam Physician 77, 47–52 (2008).
  4. Cairns, M. L. & Knable, A. L. Multiple Eruptive Milia in a 15-year-old Boy. Pediatr Dermatol 16, 108–110 (1999).
  5. Diba, V. C., Handfield-Jones, S., Rytina, E., Hall, P. & Burrows, N. Multiple eruptive milia in a 9-year-old boy. Pediatr Dermatol 25, 474–476 (2008).
  6. Hubler, W. R. Jr., Rudolph, A. H. & Kelleher, R. M. Milia en plaque. Cutis 22, 67–70 (1978).
  7. Berk, D. R. & Bayliss, S. J. Milia: A review and classification. J Am Acad Dermatol 59, 1050–1063 (2008).
  8. Tsuji, T., Sugai, T. & Suzuki, S. The mode of growth of eccrine duct milia. J Investig Dermatol 65, 388–393 (1975).
  9. Tsuji, T., Kadoya, A., Tanaka, R., Kono, T. & Hamada, T. Milia induced by corticosteroids. Arch Dermatol 122, 139–140 (1986).
  10. Rivera, A. E. Acne scarring: A review and current treatment modalities. J Am Acad Dermatol 59, 659–676 (2008).
  11. Brody, H. J. Complications of chemical resurfacing. Dermatol Clin 19, 427–438 (2001).
  12. Vlassova, N., Han, A., Zenilman, J. M., James, G. & Lazarus, G. S. New horizons for cutaneous microbiology: The role of biofilms in dermatological disease. Br J Dermatol 165, 751–759 (2011).
  13. Admani, S. & Barrio, V. R. Evaluation and treatment of acne from infancy to preadolescence. Dermatol Ther 26, 462–466 (2013).
  14. Thami, G. P., Kaur, S. & Kanwar, A. J. Surgical pearl: Enucleation of milia with a disposable hypodermic needle. J Am Acad Dermatol 47, 602–603 (2002).
  15. Pozo, J. D., Castiñeiras, I. & Fernández-Jorge, B. Variants of milia successfully treated with CO2 laser vaporization. J Cosmet Laser Ther 12, 191–4 (2010).
  16. Al-Mutairi, N. & Joshi, A. Bilateral Extensive Periorbital Milia en Plaque Treated with Electrodesiccation. J Cut Med Surg 10, 193–196 (2006).
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