Have you ever woken up one day, looked in the mirror, and seen several new pimples on your face? If yes, then these pimples could be acne (or acne vulgaris).

Acne arises from inflammation occurring on the skin. To be exact, it occurs on the pilosebaceous units. These are skin pores responsible for hair growth and sebum production. Acne can be found most commonly on faces, forehead, neck, upper chest, and shoulders, where pilosebaceous units are abundant [1]. There are three common observations associated with acne formation: overproduction of sebum, infection by skin bacteria, and abnormal follicular keratinization [2].

Overproduction of Sebum

As mentioned earlier, the pores produce sebum. Sebum is an oily liquid that protects our skin from harmful bacteria and dryness. However, too much sebum can clog the pores, causing acne to form. The production of sebum is controlled by many different factors, but one of the well-studied factors is androgens [2, 3]. Androgens are sex hormones responsible for bodily changes during puberty. Since androgen levels increase dramatically during puberty, the hormone can also cause the overproduction of sebum [3, 4]. This is why acne outbreaks are common during teenage years.

Infection by Skin Bacteria

Certain species of bacteria live on our skin. One of them, known as Cutibacterium acnes (formerly Propionibacterium acnes [5]), may involve in acne formation. C. acnes feeds on sebum, and when there is excess sebum, the bacterial population can grow and multiply. The pores clogged with excess sebum can become infected with C. acnes, which may aggravate inflammation around the area and result in acne [2, 6].

By comparing the strains of C. acnes in the pilosebaceous units on the noses of acne patients and healthy individuals, researchers reported that certain strains were strongly associated with acne but some were linked to healthy skin [7]. Revealed by genomic analysis, each of these strains contains unique genetic elements that could potentially contribute to the formation of acne or maintain skin health [7]. Further investigation on the functions of these strains could help shed light on the pathogenesis of acne and may ultimately lead to the development of targeted therapeutics [7].

Abnormal Follicular Keratinization

Keratinization is the process where a type of skin cells, keratinocyte, hardens itself with keratin proteins [8]. The hardened cells are pushed towards skin surface to form a protective layer, such as stratum corneum, which provides protection against infection, desiccation and mechanical stress [8]. However, follicular hyperkeratinization is observed in acne patient, from which a thickened layer of stratum corneum forms due to the deposition of excess keratin [6, 9]. Such a keratinous plug blocks the follicle and provides an anaerobic environment for the proliferation of C. acnes [10, 11], while the bacteria is also known to influence keratinization by secreting propionic acid (IUPAC name: propanoic acid), leading to skin cells with altered shapes [2]. These altogether result in the formation of comedo.

Below are some common misconceptions people may have about acne.

Myth #1: Only teenagers get acne.

Fact: While it is true that the many cases of acne outbreaks occur during puberty, acne outbreaks can occur anytime beyond age 20. For instance, acne outbreaks can occur before menstruation or during pregnancy in females, probably due to hormonal changes [3, 4, 11]. Stress can also lead to acne through the elevated level of stress hormones [2]. However, the underlying cause of postadolescent acne is largely unknown [11].

Myth #2: Washing your face more often will cure acne.

Fact: While this seems logical, there is no strong evidence that washing more would cure acne [10]. Antibacterial skin cleansers and acidic cleansing bars might have marginal effect on mild acne [10]. However, excessive face washing may unnecessarily remove sebum on the skin surface that normally functions to retain moisture. It dries the skin and causes the compensatory overproduction of sebum, therefore defeating the purpose of the treatment [10].

Myth #3: Eating oily food will cause acne.

Fact: There is not enough scientific evidence yet to prove that dietary fat [13], or any single food [14], can cause acne. However, speaking of diet, previous studies indicated that reducing glycemic load on diet might improve the outcome of acne [10]. Acne also seemed to be correlated with obesity [2, 10], but no evidence has proven yet that dietary restriction reduces acne [10]. More study is needed to show the causation between diet and acne [2].

Myth #4: It is OK to pop your pimple.

Fact: It’s not okay to pop your pimple on your own. Popping them with bare hands can bring more bacteria to the area and worsen the inflammation. Dermatologist are trained to do proper acne removal with sterile instruments if needed, although this is usually done only when other treatments don’t work [15].

Generally, if your acne condition persists or worsens, it’s advisable to seek advice from a dermatologist. A combination of topical retinoid and antimicrobial therapy can be prescribed to suppress inflammation by blocking the inflammatory pathways in our body and controlling the growth of C. acnes [16]. It can also reduce the blockage of pilosebaceous units by inhibiting the proliferation of keratinocytes [16].

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