What Is Acne?
Acne is a chronic inflammatory disorder of the pilosebaceous unit, involving the hair follicle and associated sebaceous gland.
It most commonly affects:
• Face
• Chest
• Back
• Shoulders
Acne severity and presentation vary widely depending on hormones, genetics, inflammation, and skin barrier function.
The Four Core Causes of Acne
From a skin science perspective, acne develops due to four interlinked processes.
1. Excess Sebum Production
Sebum is an oily substance produced by sebaceous glands to protect the skin barrier.
In acne-prone skin:
• Sebaceous glands are overactive
• Sebum composition may be altered
• Hormonal stimulation (especially androgens) increases output
Excess sebum creates an environment that supports follicular blockage and inflammation.
2. Follicular Hyperkeratinisation
This refers to abnormal shedding of keratinocytes within the hair follicle.
Instead of shedding evenly:
• Cells stick together
• The follicle becomes blocked
• Microcomedones form
This is the earliest stage of acne, often invisible but clinically significant.
3. Cutibacterium acnes (C. acnes)
C. acnes is a normal resident bacterium of the skin.
Acne is not caused by “dirty skin”, but rather by:
• Overgrowth of C. acnes in blocked follicles
• Release of inflammatory mediators
• Activation of the immune response
It is the immune reaction, not the bacteria itself, that drives acne lesions.
4. Inflammation
Inflammation is now recognised as a primary driver of acne, not just a secondary response.
Inflammation may:
• Precede visible breakouts
• Contribute to redness, swelling, and pain
• Increase risk of post-inflammatory hyperpigmentation and scarring
This explains why some clients experience acne even with minimal visible congestion.
Types of Acne Explained
Understanding acne type is essential for appropriate management.
Non-Inflammatory Acne
• Open comedones (blackheads)
• Closed comedones (whiteheads)
Inflammatory Acne
• Papules
• Pustules
• Nodules
• Cysts
Inflammatory acne carries a higher risk of scarring and pigmentation changes, particularly in higher Fitzpatrick skin types.
Hormonal Acne and Adult Acne
Hormonal influence is a major contributor, particularly in adult clients.
Features often include:
• Lower face and jawline distribution
• Fluctuation with menstrual cycle
• Resistance to topical treatments alone
Hormones influence sebum production, inflammation, and follicular behaviour, making adult acne complex and persistent.
The Role of the Skin Barrier in Acne
A compromised skin barrier can:
• Increase inflammation
• Worsen sensitivity
• Reduce tolerance to active ingredients
• Delay healing
Over-exfoliation and inappropriate product use often exacerbate acne rather than improve it.
Barrier repair is therefore a critical component of acne management.
Why Acne Keeps Coming Back.
Acne is not a short-term condition for many clients because:
• Hormonal influences persist
• Inflammation may remain subclinical
• Barrier dysfunction is ongoing
This highlights the importance of long-term skin management, not just breakout suppression.
Why Skin Science Matters in Acne Treatment
Without understanding the pathophysiology of acne, treatment becomes:
• Reactive rather than strategic
• Trend-led rather than evidence-based
• Higher risk for complications such as scarring
Skin science allows practitioners to educate clients, manage expectations, and plan treatment safely.
Final Thoughts
Acne is a complex inflammatory condition influenced by sebum, keratinisation, bacteria, inflammation, and barrier health.
For aesthetic practitioners, effective acne management begins with understanding what causes acne, rather than chasing individual lesions.
Advance your Acne Knowledge
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