The Definitive Guide to Acne

Acne is a common, potentially devastating condition that afflicts millions of people globally every year.

However, very effective treatment can reliably clear acne minimising the risk of complications, such as scarring, impacts on self-esteem, and mental health.

How common is acne?

It is traditionally considered an issue affecting teenagers, however, it is now better thought of as a chronic condition that is more commonly affecting people well into their adult years.

It can start as young as seven and will resolve by the early twenties for most. However, up to 50% of those in their twenties and 35% of those in their thirties still suffer from the condition.¹

What causes acne?

Acne development: Increased sebaceous glands and sebum, increased and abnormal keratin.

Acne is a disorder of the pilosebaceous units in the skin. These structures are comprised of the hair follicle, hair shaft and sebaceous (grease) glands.

It is thought to result from:

increased and disordered keratin production (follicular hyperkeratinisation).
increased sebum production (seborrhoea).
accumulated keratin and sebum results in closed comedones.
melanin (skin pigment) and oxidized lipids inside the comedone give comedones their black colour.
the bacterium Cutibacterium acnes contributes to inflammation and swelling of the pilosebaceous unit.
a complex interaction of hormonal stimulation of the sebaceous glands, the microbiome, and the immune response.

Hormonal Influences

Hormones, in particular androgens (male hormones) do play a role in the development. However, this is not due to elevated or abnormal levels of hormones, as almost all sufferers have normal hormone levels.

Rather, it is an increased sensitivity of the pilosebaceous unit to these hormones. Genetics also play a part as first-degree (immediate) relatives have more than three times the risk of developing acne.²^,³^,⁴

Cutibacterium acnes

Cutibacterium acnes (C. acnes) is a normal component of the bacterial flora of the skin, however, in the context of abnormal pilosebaceous units, it appears to contribute to an inflammatory response from the immune system.⁵^,⁶

Furthermore, some strains of C. acnes have been identified that are more likely to promote inflammation and the development of acne.⁷ Interestingly, vitamin A and vitamin D may play a role in suppressing the inflammatory response to C. acnes.⁸ Different strains of C. acnes and people’s differing inflammatory responses to the bacteria are thought to contribute to varying severities.

Can modifying my diet help with my acne?

This is an incredibly commonly asked question. Across all of medicine, dietary studies are notoriously unreliable, as they usually rely on someone’s memory recall of what they consumed. As such the conclusions of dietary studies need to be interpreted with care.

Studies since as early as the 1970’s have found little or no association between diet and acne. However, recent studies, have started showing small associations.

Dairy: Some studies have shown an association between dairy consumption and acne. Interestingly, skim milk has a stronger effect than whole milk. The Nurses’ Health Study collected retrospective data from 47,355 women and demonstrated an association between acne and intake of cow’s milk.⁹ This was supported by several other case-control studies.¹⁰^,¹¹^,¹²^,¹³ It is thought that the natural hormonal components of cow’s milk exacerbates acne. Milk consumption was also related to increased levels of serum IGF (insulin-like growth factor).
Sugar: A study has demonstrated a reduction in acne when switching to a low-glycemic (sugar) index diet which also influences IGF levels. However, the low-glycemic diet participants also lost more weight than the control group, confusing the interpretation of this study.¹⁴^,¹⁵
Body weight: It is unclear whether a higher body mass index (BMI) is associated. Conflicting studies have shown both an increased and decreased risk of acne for individuals with a high BMI.¹⁶^,¹⁷
Chocolate: There is no evidence that chocolate increases the risk of development.
Stress: Studies have shown that stress does appear to increase the severity of acne.¹⁸^,¹⁹

Clinical features of acne

Acne can present with several different types of lesions, including comedones, papules, pustules, nodules, and cysts. Redness (erythema) and pigmentation can also be significant features. It can also vary widely in terms of severity and distribution. The most common areas affected are the face and back, but can also affect the chest and upper arms.

Traditionally, severity was graded based on specific criteria. However, this is not particularly relevant for modern treatments. The most important factors that guide treatment are the presence of scarring and the psychological impact or distress that it is causing.

Diagnosis and investigations for acne

Almost all cases of acne will be diagnosed during a routine consultation with a dermatologist without the need for further investigations.

Investigations are generally only undertaken when there are indications of an underlying disorder. This includes:

For women, suggestions of increased male hormones. This can include irregular periods, excess hair, deep voice, or increased musculature.
Children under the age of six years old.
Abnormally abrupt onset or severe acne.
Suspicion of SAPHO syndrome (severe acne associated with joint or bone pain).

The development of the condition in preadolescents (ages 7 to 12 years) does not require further investigation without other signs disease.

Acne severity

In principle, treatment is influenced by the severity acne. However, this is not the only factor considered. The most important impacts of acne are:

evidence of scarring
impact on psychological well-being or self-esteem

If either of these are evident, we recommend seeing a dermatologist as soon as possible.

Dermatologists have the skills to essentially switch off acne, limiting the impact of scarring and psychological complications. We also recommend input from dermatologists even when it only has a moderate severity, as the development of scars can be prevented.

While there is no universal severity scale, severity generally falls into key groupings that guide treatment.

Mild acne

Scattered small papules or pustules
Limited areas affected: either one area (e.g., the face) or small amounts in a few body regions (e.g., the face, chest, and back)
No evidence of nodules or scarring

Moderate-to-severe acne

Includes anything that does not fall into the mild category, in particular:

Evidence of scarring
Numerous papules or pustules
Nodules or cysts
Significant involvement of more than one body site
Significant psychological impact or distress

Treatment

There are numerous treatments available and each treatment has its own relative benefits and downsides.

It is also important to realise that most treatments only suppress the inevitable and therefore require ongoing maintenance treatment until a person ‘grows out’ of their acne. In some cases, this can take several years. Isotretinoin is the only treatment that can result in a long-term cure for acne.

While treatment is normally discussed in terms of acne severity, other factors to consider are:

Likelihood of future development of scarring.
Impact of acne on quality of life
Ease of treatment and likely compliance
An individual’s desire for a ‘curative’ treatment so they can ‘get on with life’
Potential side effects of treatment

Mild acne treatment

Topical agents are typically the main treatments for mild cases. A key part of treatment is monitoring for a response. With topical treatment regimens, complete clearance should not be expected, but improvement should occur within 12 weeks.

If improvement is not forthcoming, more effective treatments should be considered. Treatments that are normally used for moderate-to-severe cases can also be used for those with milder severity if they want more effective treatments or completely clear skin.

Over-the-counter (OTC) topicals

Over-the-counter topical agents can be purchased without a prescription from stores such as supermarkets and pharmacies. While they do work, their efficacy is lower than that of prescription treatments. On average, they can improve mild acne by about 30% to 50%.

While there are countless options available, they generally include the same basic active ingredients. Some of those ingredients are:

Antiseptics/antimicrobials: benzoyl peroxide is the main treatment in this group. Concentrations higher than 2.5% benzoyl peroxide do not substantially increase efficacy but are more likely to cause irritation.²⁰ Alternatives include clindamycin.
Exfoliants: salicylic acid tends to be more effective than azelaic acid for acne, however, azelaic acid can help with post-inflammatory hyperpigmentation. Salicylic acid is often used as an alternative to topical retinoid treatment for those who prefer it.
Tea-tree oil: there is some evidence that tea-tree oil can help with acne, however, it is significantly less effective than the above options.²¹

Treatments from different categories are often combined to optimise their efficacy. An example would be using benzoyl peroxide and salicylic acid. Care should be should be taken with additive skin irritation when combining treatments.

Prescription topical agents

The main topical treatments that require a prescription are retinoids such as tretinoin and adapalene. Due to their superior efficacy, they should ideally be included in any treatment regime for mild acne.

While topical retinoids can be used alone, their efficacy can be boosted when used with other agents like benzoyl peroxide.²²

Moderate-to-severe acne treatments

While topical agents can be used for moderate-to-severe cases, the superior efficacy of systemic (tablet) agents usually necessitates their use. As such, systemic agents are the mainstay of treatment. Clinic procedural treatments such as lasers and chemical peels can help, but they should be considered secondary treatments that can be used in combination with systemic agents to improve results.

Treatment options include:

Antibiotics: several antibiotic treatments are available and can generally improve acne by about 40% to 70%. The preferred option is doxycycline.²³
Hormonal: these treatments are an option for females by reducing the effect of androgens and therefore sebum production. Options include oral contraceptive pills, and cyproterone acetate. Efficacy is thought to be similar to oral antibiotics, but unfortunately, they take much longer to work (up to three to six months to notice improvement).²⁴
Oral retinoids: isotretinoin is by far the most effective treatment and the only treatment that treats all components of acne. Its efficacy approaches 100% while taking the medication, and is the only treatment that can result in a long-term cure.²⁵^,²⁶^,²⁷

Lasers and light treatments: in general, there is limited about the efficacy of these treatments for acne, however, they can be used as adjuncts (e.g., to clear redness more quickly).
- Blue-red light was slightly more effective than benzoyl peroxide in a small study.²⁸
- Some studies have demonstrated efficacy for photodynamic therapy (PDT), whereas others were less favourable.²⁹
- Other light treatments such as blue light, intense pulsed light (IPL), and pulse-dye laser (PDL) have been proven to be less effective than commonly used topical treatments.³⁰^,³¹^,³²

Medical peels: these can be effective, however, the treatment process can be involved, and a recovery period is required. Ongoing treatments are usually required, which can end up being expensive. Peels should be avoided in those with inflammatory cases due to the higher risk of making it worse. Studies have shown that overall improvement is about 20% to 30% which is less than other treatments.³³

Treatment for pigmentation

Please note this section may seem vague as we have avoided naming some specific medications. Regulators, particularly Medsafe don't allow us to write about the Off-Label Use of medications. However, these are permitted to be discussed during your consultation, so you are welcome to ask.

Post-inflammatory hyperpigmentation can cause significant distress and is more common in those with darker (pigmented) skin. Rigorous sun protection is very important to minimise the impact of this. There are some treatment options that can help with this such as:

Several topical preparations
Chemical peels are effective, however, the improvement can be limited

What about other Treatment Options?

There are endless treatment options found on the internet. Many of these treatments are questionable and exist in the realm of pseudo-science. Dermatologists are ethically bound to only recommend treatments that are evidence-based. Doctors can be censured by the Medical Council of New Zealand for recommending treatments that are not evidence-based.

Complications

Scarring is a common complication of acne.

By far the most common complication of the condition is the development of scarring. While scars are essentially permanent, the appearance of scars can be improved by a range of treatments.

Pigmentation (staining) of the skin is common in those with darker skin. This can be quite distressing for people, even in mild cases. Post-inflammatory hyperpigmentation typically resolves without treatment, however, it can take several months to do so.

Acne can have a significant impact on psychological well-being and self-esteem. Unfortunately, this aspect of the condition is often overlooked and frustratingly delays effective treatment. This can be so severe that it results in suicide.³⁵

Some studies have shown that the long-term psychological impacts of acne can affect social relationships and career choices.

Prognosis

Due to the availability of very effective treatments, it is no longer necessary to suffer from acne, as it is now considered curable. Some treatments have long-term cure rates of around 70% with a single course.

Treatment by a specialist dermatologist can help avoid and minimise the development of scarring while maintaining psychological well-being.

Disclaimers

Benzoyl Peroxide Statement

Benzoyl peroxide is prescription medicine for the treatment of acne vulgaris. Benzoyl peroxide has risks and benefits. Ask your doctor if benzoyl peroxide is right for you. If you have side effects, see your doctor.