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Causes, treatment and prevent of Acne

Updated: Sep 4, 2023

An information discussion on Acne, its causes, available treatment options and how to prevent recurrence

Written by Dr Amanda Chen


I decided discussing acne in our first article entry for the website is apt, as everyone would have experienced some form of acne in their lifetime, whether mild, moderate or severe, and affects a wide age range, from teenagers to adults, regardless of ethnicity or nationality. It is also one of the most common conditions my patients present with.

A large proportion of patients presenting with acne are teenagers and young adults, however, older adults also visit the clinic for active acne lesions, although most older adults tend to be more concerned with residual atrophic scarring from previous acne lesions. More recently, I have also observed an increasing number of patients presenting with acne, likely related to mask wearing regulations here due to the recent coronavirus pandemic. Mask wearing results in abrasion of the skin from friction caused by the surgical face mask, and also traps humidity on the skin, all of which contributes and perpetuates an environment for the formation of acne vulgaris.

Acne vulgaris is mainly influenced by genetics, and results from an inflamed pilosebaceous unit, which is caused by these primary factors(1):

  1. Follicular hyperkeratinsation resulting in blockage of the follicle

  2. Follicular colonization of the commensal skin bacterial species, Cutibacterium acnes

  3. Production of inflammatory mediators triggered by C.acnes

  4. Overactive sebaceous glands

  • Regulated by androgens

  • Stress related hormones such as adrenocorticotrophic hormone (ACTH) also trigger sebaceous glands(2)

It is considered to be the commonest skin disease in developed countries, with 80% of the population affected by acne at any point during their lifetime. About one-fifth of those affected have severe acne, and this can result in permanent scarring and mental health issues.(3)

Occurrence amongst adolescents and young adults is highest, with 85% of those aged 12 to 24 having acne,(4) as during puberty, more androgen hormones are produced and secreted. However, acne also continues to affect about 5% of those over age 45.(5) Amongst adolescents, males are more affected than females, however in later adulthood, acne tends to affect more women.(4)

Acne commonly occurs on areas of skin where there is a large presence of pilosebaceous units such as that of the face, chest and back. It is classified as non-inflammatory (opened or closed comedones) or inflammatory acne (papules, pustules, nodules and cysts).

Acne vulgaris can also be further classified as mild, moderate or severe, in order to distinguish the grading and severity for determination of the appropriate targeted stepwise escalation of acne treatment, as well as to clinically record an observation of the patient’s acne lesions and for follow-up assessment, in order to objectively determine if there is any clinical response to the treatments prescribed.

The different types of acne are described(6):

  • Comedonal acne: Open or closed comedones with no inflammatory lesions

  • Mild acne: Comedones with some papulopustules

  • Moderate acne: Comedones, more inflammatory papules and pustules than in mild acne

  • Nodulocystic acne: Comedones, inflammatory papules and pustules, and large nodules larger than 5mm in diameter. May be accompanied by scarring

The severity of acne grades can be defined by the number of comedones, inflammatory papules or pustules, or the overall number of lesions present.(7)

  • Mild acne: Less than 20 comedones, less than 15 inflammatory lesions, or less than 30 overall lesions

  • Moderate acne: 20-100 comedones, 15-50 inflammatory lesions, 30-125 overall lesions

  • Severe acne: More than 100 comedones, more than 50 inflammatory lesions, more than 5 pseudocysts, more than 125 overall lesions


Acne vulgaris is diagnosed by clinical observation. However, further investigation with blood laboratory testing may be required in patients who present with concomitant symptoms indicative of hyperandrogenism. If polycystic ovarian syndrome is suspected (oligomenorrhoea, amenorrhoea, hirsutism, acanthosis nigricans in females), blood testing for total and free testosterone, DHEAS, luteinizing hormone, follicle stimulating hormone, lipid panel and fasting glucose should be done. For patients who are unresponsive to antibiotic therapy, consider sending off bacterial culture to exclude the diagnosis of a gram-negative folliculitis.(8)


Treatment depends on the severity and grading of acne. This is detailed in the chart below.

In addition to the above prescribed treatments, in clinic treatments to help speed up healing of acne as well as deep acne scars (icepick, rolling and boxcar scars), or post-inflammatory erythema (PIE) and post-inflammatory hyperpigmentation (PIH) include lasers such as pico lasers or fractional CO2 lasers, chemical peels, fractional RF microneedling, Rejuran Healer and Rejuran Scar, subcision and dermal fillers. Persistent nodular/cystic acne may be treated with intralesional steroid injections.


Acne vulgaris affects both genders, as well as most age groups, with teenagers and young adults experiencing acne the most. There are a lot more aspects to acne than just the skin lesions and appearance, as it also tends to leave long-lasting psychological and physical impacts on the patient. These include low and depressed mood and permanent scarring, which can be difficult to treat and involves a high cost and a lot of trips to the clinic. As such, it is imperative that patients present early and that the correct treatment is initiated early on, so as to reduce the risk of unwanted adverse effects that inflammatory acne can have.


  1. Nelson LR. Acne Vulgaris. In: Reference Module in Biomedical Sciences. Elsevier; 2021.

  2. Makrantonaki E, Ganceviciene R, Zouboulis C. An update on the role of the sebaceous gland in the pathogenesis of acne. Dermatoendocrinol [Internet]. 2011;3(1):41–9.

  3. Connolly D, Vu HL, Mariwalla K, Saedi N. Acne scarring-pathogenesis, evaluation, and treatment options. J Clin Aesthet Dermatol. 2017;10(9):12–23.

  4. Skin conditions by the numbers. [cited 6 February 2022]. Available from:

  5. Kligman AM. Postadolescent acne in women. Cutis. 1991 Jul. 48(1):75-7.

  6. Oge’ LK, Broussard A, Marshall MD. Acne vulgaris: Diagnosis and treatment. Am Fam Physician. 2019;100(8):475–84.

  7. Muller GH. Acne Vulgaris. In: Spontaneous Animal Models of Human Disease. Elsevier; 1979; 29–30.

  8. Dréno B, Poli F, Pawin H, Beylot C, Faure M, Chivot M, et al. Development and evaluation of a Global Acne Severity Scale (GEA Scale) suitable for France and Europe: Global acne assessment scale. J Eur Acad Dermatol Venereol. 2011;25(1):43–8.

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