How do blackheads and blemishes form?

Beneath the surface · Part three

In Part Two of Beneath the Surface, we looked at why skin often becomes oilier during puberty.

But oily skin does not automatically mean blemished skin. So how do blackheads, whiteheads and inflamed blemishes develop? The answer starts inside the hair follicle.

It starts with a tiny blockage

Each hair follicle is connected to a sebaceous gland, which produces sebum, the oily substance we discussed in Part Two.

Sebum is not dirt. It is a normal part of healthy skin (Del Rosso & Kircik, 2024).

During puberty, sebaceous glands become more active and produce more sebum. At the same time, cells lining the upper part of the follicle can start to build up instead of shedding normally. Together, these changes can cause cells and sebum to build up within the follicle, forming the earliest stage of a blockage (Xie et al., 2024).

This early blockage is called a microcomedone. It is too small to see, but it is an important early step in the development of blackheads, whiteheads and some inflammatory acne lesions (Xie et al., 2024).

So how does a blackhead form?

As the blockage grows, it may become visible.

If the follicle remains closed at the surface, it forms a closed comedone, commonly called a whitehead.

If it opens at the surface, it forms an open comedone, or blackhead.

The dark part of a blackhead is not trapped dirt. The mix of sebum and skin cells within the open follicle is exposed to air, and the oxidation contributes to its dark appearance.

Blackheads are therefore not a sign that a teenager's skin is dirty or that they are not washing properly. Scrubbing harder is not the answer.

Where do bacteria fit in?

You may have heard that acne is caused by a bacterium called Cutibacterium acnes, or C. acnes. C. acnes does play a role, but it is not simply a harmful bacterium that needs to be removed. It normally lives on human skin, including the skin of people without acne.

Research suggests that acne involves changes in the environment inside the follicle, differences in C. acnes strains and other microorganisms, and the way the immune system responds (Dreno et al., 2024).

The goal of everyday skincare is therefore not to make skin "bacteria-free", but rather to support the good bacteria living naturally on your skin.

Why do some blemishes become inflamed?

Acne is not caused by one single process. Changes in sebum production, the build-up of cells within the follicle, C. acnes and the skin's inflammatory response can all interact (Cruz, Vecerek & Elbuluk, 2023).

When inflammation develops around the follicle, a blemish can become red, swollen or tender. It is too simplistic to think of acne as simply "too much oil" or "dirty pores". Different factors contribute to the severity of blocked pores and inflammation in individuals.

What is a sensible approach to teenage skincare?

For parents, the important message is that these changes during puberty are common. A teenager with oily skin, blackheads or blemishes is not necessarily doing anything wrong.

Repeated washing, scrubbing or using multiple strong products will not solve what is happening inside the follicle and may irritate the skin.

A sensible skincare routine must do three things: clean the skin gently, help keep pores clear and support the skin through the changes of adolescence.

Cosmetic skincare also has limits. Persistent, painful or worsening acne, particularly acne that is leaving scars or dark marks, or causing significant distress, should be assessed by a healthcare professional. Effective acne treatments are available, and early treatment can help reduce the risk of scarring (Reynolds et al., 2024).

Teenage skin does not need to be scrubbed into submission. Understanding what is happening beneath the surface is a much better place to start.

References

Cruz, S., Vecerek, N. & Elbuluk, N. (2023) 'Targeting inflammation in acne: Current treatments and future prospects', American Journal of Clinical Dermatology, 24(5), pp. 681–694. doi: 10.1007/s40257-023-00789-1.

Del Rosso, J.Q. & Kircik, L. (2024) 'The primary role of sebum in the pathophysiology of acne vulgaris and its therapeutic relevance in acne management', Journal of Dermatological Treatment, 35(1), 2296855. doi: 10.1080/09546634.2023.2296855.

Dreno, B., Dekio, I., Baldwin, H., Demessant, A.L., Dagnelie, M.A., Khammari, A. & Corvec, S. (2024) 'Acne microbiome: From phyla to phylotypes', Journal of the European Academy of Dermatology and Venereology, 38(4), pp. 657–664. doi: 10.1111/jdv.19540.

Reynolds, R.V., Yeung, H., Cheng, C.E., Cook-Bolden, F., Desai, S.R., Druby, K.M., Freeman, E.E., Keri, J.E., Stein Gold, L.F., Tan, J.K.L., Tollefson, M.M., Weiss, J.S., Wu, P.A., Zaenglein, A.L., Han, J.M. & Barbieri, J.S. (2024) 'Guidelines of care for the management of acne vulgaris', Journal of the American Academy of Dermatology, 90(5), pp. 1006.e1–1006.e30. doi: 10.1016/j.jaad.2023.12.017.

Xie, L., Hamblin, M.R., Zheng, D.L. & Wen, X. (2024) 'The role of microcomedones in acne: Moving from a description to treatment target?', Journal of the German Society of Dermatology, 22(1), pp. 9–16. doi: 10.1111/ddg.15272.