What causes Acne Vulgaris and Acne Scars?
Acne Vulgaris
The condition results from the following events:
- Bacterial colonisation – the bacterial species Cutibacterium acnes (C. acnes), previously known as Propionibacterium acnes, colonises the follicular plug and breaks down sebum to form free fatty acids.
- Follicular clogging – excess sebum and dead skin cells can form a plug in the hair follicles.
- Increased sebum production – sebum is the oily substance produced by the sebaceous glands, which functions to hydrate and protect the skin. But overproduction of sebum can clog the hair follicles.
- Inflammation – bacterial infection and free fatty acids present in the lesion irritate the follicular epithelium. This then elicits an inflammatory response from the immune system, leading to the recruitment of white blood cells, such as lymphocytes and neutrophils, to the site of inflammation. This eventually leads to pain, redness, swelling and pus formation.
While these events cause the development of acne lesions, several factors can increase the likelihood of acne formation. These include:
- Comedogenic products or cosmetics – occlusive products can clog the hair follicles, leading to acne formation.
- Hormonal changes – hormonal changes, such as puberty, pregnancy or premenstrual period, are associated with acne flare-ups. This is likely due to an increase in sebum production associated with an increase in androgen levels.
- Medications – use of certain medications such as lithium, steroids and anticonvulsants may increase the risk of developing acne.
- Underlying conditions – underlying conditions such as polycystic ovarian syndrome (PCOS) or insulin resistance are associated with acne.
- Stress – stress may increase stress hormones, which can stimulate excess sebum production.
Acne Scars
They form during the skin’s healing process after inflammatory acne. Several factors contribute to this, such as:
- Inflammation – inflammation in acne lesions can cause red marks (post-inflammatory erythema or PIE) or dark spots (post-inflammatory hyperpigmentation or PIH). But generally:
- PIE is more common in fair skin
- PIH is more common in darker skin
- Increased melanin production contributes to PIH
- Residual dilated or damaged blood vessels following inflammation causes PIE
- Granulation tissue – as the skin heals, it forms new tissues made of collagen and blood vessels. This helps repair the skin but may leave scars if the process is disrupted.
- Matrix remodelling – skin cells release enzymes called MMPs during the healing stage. They break down collagen and other parts of the skin structure. However, they can cause depressed or raised scars if there is an imbalance between MMPs and their natural blockers (TIMPs).
While we cannot entirely avoid acne scars, several factors can increase the risk. This may include:
- Picking or squeezing – this worsens inflammation and damages the skin, making scars more likely.
- Severity of acne – deeper, more inflamed acne causes more damage and leads to worse scarring. However, early treatment helps prevent this.
- Duration of inflammation – the longer acne stays inflamed, the higher the risk of lasting scars. As such, reducing inflammation quickly is pivotal.
How is Acne Vulgaris treated?
Treatment may be a standalone or a combination of the following:
Topical treatments
- Retinoids – these are often the first choice for treating acne. They help unclog pores by speeding up skin cell regeneration and reducing inflammation. Adapalene is usually the first option, while tretinoin or trifarotene may be used if stronger treatment is needed.
- Antibiotics – topical antibiotics help kill acne-causing bacteria and are often used with other treatments like retinoids or benzoyl peroxide.
- Benzoyl peroxide – this is an antibacterial agent that stops bacteria from growing in acne lesions. It is often combined with antibiotics to reduce resistance and improve results.
- Keratolytic agents – these gently exfoliate the skin and prevent blocked pores. Some common examples include salicylic acid and azelaic acid. Both acids possess antimicrobial and anti-inflammatory properties.
- Dapsone – a topical gel that helps reduce acne through its anti-inflammatory and antibacterial properties. It is usually used in specific cases where other treatments are insufficient.
- Clascoterone (winlevi) – this is a topical anti-androgen used to treat acne. It works by blocking hormones in the skin that cause excess oil production and inflammation. This helps reduce breakouts, especially in hormonal acne. It is often used when other topical treatments aren’t effective enough.
Systemic treatments
- Oral retinoids – isotretinoin is a strong oral medication used to treat moderate to severe acne. It works by shrinking the oil glands. This reduces sebum production and bacteria on the skin. However, it is not recommended for pregnant or breastfeeding women.
- Oral antibiotics – these work by reducing acne-causing bacteria in the skin. Common options include doxycycline, minocycline and erythromycin. They are often used for moderate acne or when topical treatments are insufficient.
- Hormonal treatments – these helps balance hormone levels that affect oil production, especially in women with high androgen levels like testosterone. Options include oral contraceptives and anti-androgens such as spironolactane.
Intralesional injections
For painful cystic or inflamed acne lesions, corticosteroid injections can provide quick relief and reduce the risk of scarring. The medication is injected directly into the affected spot to calm inflammation.
However, this treatment is used sparingly. Frequent injections can lead to side effects such as skin thinning (atrophy) or lightening of the skin (hypopigmentation).
How are Acne Scars treated?
Preventing or treating acne scars starts with proper acne treatment and reducing skin inflammation early. This may include:
Atrophic scars
- Chemical peels – these masks use acids to exfoliate the top layers of the skin to encourage skin renewal and reveal a smoother texture. Common peeling agents include glycolic acid, lactic acid, salicylic acid, pyruvic acid and trichloroacetic acid.
- Dermabrasion or microdermabrasion – these treatments resurface the skin by removing its upper layers to promote healing. However, the both function differently:
- Dermabrasion is more invasive and removes deeper layers of skin, making it suitable for deeper scars.
- Microdermabrasion is gentler, removing only the outermost layer, with shorter recovery and fewer side effects.
- Laser treatments – this treatment helps resurface the skin and stimulate collagen by:
- Ablative lasers remove the top skin layers and promote collagen production beneath the surface.
- Non-ablative lasers do not remove skin layers but still boost collagen formation. These have shorter downtime and fewer risks.
- Microneedling – this creates controlled micro-injuries in the skin to stimulate healing and collagen growth. It may be combined with other treatments to enhance results, including antibacterial and nourishing therapies.
- Punch excision – this surgical method removes deep, pitted scars using a small tool, followed by stitching to close the wound.
- Fillers – dermal fillers can be injected into depressed scars to lift them, improving skin texture and making the scars less noticeable.
Hypertrophic scars
Unlike atrophic scars, hypertrophic and keloid scars form due to excess collagen. Treatment usually focuses on reducing scar size and flattening the raised tissue.
- Intralesional corticosteroid injections – these are commonly used to shrink raised scars. The steroids reduce inflammation, size and firmness of the scar and help relieve itching or discomfort.
- Laser therapy – pulsed dye lasers are often used to reduce redness They work by targeting blood vessels and breaking down excess collagen in the scar tissue. Ablative lasers can help flatten raise scars.
