What Causes Acne? Hormones, Diet, and Environmental Factors

Acne is one of the most common skin conditions, affecting nearly 85% of people between the ages of 12 and 24, although it can persist or develop at any age. Characterized by pimples, blackheads, whiteheads, and sometimes more severe cysts, acne can cause physical and emotional distress.

Its root causes are complex and multifaceted, which can make treatment challenging. Hormonal fluctuations, environmental factors, and dietary habits all play a role in the development of acne, and the way these factors interact can vary widely among individuals. This article aims to explore these key contributors to acne, offering an evidence-based understanding of how each factor impacts the skin.

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The Basics: How Acne Develops

Acne develops when hair follicles, or pores, become clogged with a combination of excess oil (sebum), dead skin cells, and bacteria. Normally, sebum helps protect and moisturize the skin, but when it is produced in excess, it can mix with dead skin cells, forming a plug in the pore. Bacteria, particularly Cutibacterium acnes (formerly Propionibacterium acnes), can grow in the clogged pores, leading to inflammation and acne.

There are two main types of acne:

Non-inflammatory acne includes blackheads (open comedones) and whiteheads (closed comedones), which are caused by clogged pores without significant bacterial involvement or inflammation.
Inflammatory acne, on the other hand, includes papules, pustules, nodules, and cysts, which are characterized by pus, redness, swelling, and pain. When bacteria thrive within clogged pores, the immune system responds by sending white blood cells to the area to fight the infection, inducing the hallmark symptoms of inflammation.

Genetics also play a role in an individual's susceptibility to acne. Research suggests that people with a family history of acne are up to three times more likely to develop the condition. The expression of certain genes, such as interleukin (IL), tumor necrosis factor (TNF), and cytochrome P450 (CYP), influences acne development and severity through the upregulation of sebaceous gland function and inflammation.

Hormonal Factors: The Primary Driver of Acne

Hormonal acne is a type of acne that is caused by hormonal changes that increase the activity of sebaceous glands. Androgens (male sex hormones), including dehydroepiandrosterone (DHEA), testosterone, and dihydrotestosterone (DHT), are the primary drivers of hormonal acne because they bind to receptors on skin cells and upregulate sebum production. Seborrhea (excess oil production) creates a favorable environment for C. acnes to thrive because the bacteria break down the oils in the skin into molecules called fatty acids and glycerol that they use as food. (55)

The role of androgens in acne pathophysiology explains the prevalence of acne during puberty. Other medical conditions associated with elevated androgen levels can cause acne to persist through adulthood, including:

Polycystic ovary syndrome (PCOS)
Congenital adrenal hyperplasia (CAH)
Androgen-secreting tumors

Fluctuations in estrogen and progesterone during the menstrual cycle, pregnancy, and menopause significantly influence adult hormonal acne in females. Estrogen helps regulate skin health by shrinking sebaceous glands and reducing sebum production through lowering androgen levels. In contrast, high levels of progesterone are often measured in women with acne despite progesterone's ability to inhibit the conversion of testosterone to DHT, which would be thought to reduce sebaceous gland activity. This discrepancy highlights the need for further research to better understand how estrogen and progesterone influence sebaceous gland function and acne development. (35, 38)

Other hormonal factors also must be considered in the development of acne, as elevations in growth hormone, insulin, cortisol, adrenaline, prolactin, and thyroid hormones can all stimulate sebum secretion and exacerbate acne (13).

The Role of Diet in Acne

Research strongly suggests that the origin of many skin diseases can be traced back to the gut, thanks to the gut-skin axis. This axis refers to the bidirectional communication between the gut microbiome and the skin, highlighting how the health of the digestive system can influence skin health and vice versa.

The gut microbiome, which consists of a diverse community of microorganisms residing in the digestive tract, helps regulate immune responses, nutrient absorption, and systemic inflammation. Disruptions in this microbiome, known as dysbiosis, can contribute to the systemic inflammation and immune system dysfunction involved in the development of acne.

What we eat can significantly affect the composition of the gut microbiome. Diets high in processed foods, sugars, and dairy products have been associated with increased risk for dysbiosis and leaky gut. In contrast, balanced anti-inflammatory diets promote a balanced microbiome and healthy digestive tract.

Studies highlight specific dietary choices that appear to most heavily exacerbate acne. High glycemic index foods, such as sugar snacks and refined carbohydrates, exacerbate acne by causing rapid spikes in blood sugar, insulin, and insulin-like growth factor 1 (IGF-1) levels. These spikes can increase sebum production and promote inflammation (45).

Similarly, dairy products have been linked to acne flare-ups due to the increases in IGF-1 levels they induce.

Environmental and Lifestyle Factors That Contribute to Acne

Airborne pollutants, such as particulate matter from traffic, industrial emissions, and smoke, can settle on the skin, leading to clogged pores and oxidative stress. These pollutants penetrate the skin barrier, causing inflammation and irritation, worsening acne. Research has shown a correlation between high levels of air pollution and increased acne severity.

Temperature and humidity also influence acne by affecting oil production. Hot, humid environments cause the skin to produce more sweat and oil, which can mix with dead skin cells and bacteria, leading to clogged pores. One study found that sebum excretion rate increased by 10% for every 1°C increase in temperature. (63)

"Maskne," a term coined during the COVID-19 pandemic, refers to acne and other skin issues caused by frequent and prolonged mask-wearing. As masks became a new standard, many individuals began experiencing acne flare-ups in the areas of the face covered by masks (the nose, cheeks, and chin, collectively known as the "O zone"). Increased heat, humidity, mechanical friction, and facial microbiome disruption are the primary culprits behind the increased acne associated with mask-wearing.

Comedogenic products are those with ingredients that hold the potential to clog pores and cause acne. There is an extensive list of comedogenic ingredients, most of which come from information gathered from a 1984 study on rabbits, including:

Isopropyl palmitate
Buyl stearate
Myristyl myristate
Decyl oleate
Octyl stearate
Propylene glycol-2
Lanolin
Coal tar derivates, including D&C red dyes

The Combined Effect: How These Factors Interact

Acne is rarely caused by a single thing; rather, it is often the result of a complex interplay between hormones, diet, environment, and lifestyle, each influencing and amplifying the effects of the others. These factors are interrelated, creating a cycle that can exacerbate acne, making it difficult to isolate one cause.

For example, high stress activates the release of cortisol and often predisposes people toward unhealthy emotional eating habits. Collectively, these can act to fuel additional hormonal imbalances and systemic inflammation, creating a feedback loop that makes acne more challenging to manage.

Strategies for Managing Acne Caused by These Factors

Understanding the likely causes behind acne empowers individuals to make informed treatment decisions that can effectively break the cycle of acne breakouts and restore skin balance.

Balancing Hormones

Standard of care medical guidelines propose the use of combined oral contraceptive pills (OCPs) and antiandrogenic medications to treat hormonal acne. These medications work through various mechanisms to correct imbalances in sex hormones that are associated with driving acne lesion development. (30)

For those seeking a more natural approach, the following strategies help in tackling the underlying causes of hormone imbalance:

Manage stress by prioritizing good quality sleep, exercising regularly, and utilizing mind-body therapies.
Eat a diet rich in nutrients required for hormone synthesis, metabolism, and elimination, such as fiber, protein, healthy fats, and phytonutrients.
Reduce inflammation, which drives insulin resistance and androgen excess, by eating an anti-inflammatory diet and taking supplements that inhibit the production of inflammatory signaling molecules, such as omega-3 fatty acids and curcumin.

Diet Adjustments

Western diets are marked by excessive intake of processed foods, red meat, and sugar and low intake of fruits and vegetables. A study involving over 1,200 participants in South Korea highlighted the aggravating role Western dietary patterns play on acne. Those with more severe acne consumed significantly more processed foods, snacks, dairy, and meat and had higher IGF-1 levels than those without, who ate diets with a generally higher intake of vegetables and fish.

Conversely, diets rich in omega-3 fatty acids, antioxidants, and fiber have been associated with reduced acne severity. This may stem from these nutrients' ability to modulate inflammation and support a healthy gut microbiome.

Skincare and Environmental Control

A non-comedogenic skincare routine prevents and manages acne by focusing on cleaning and treating the skin with products that do not clog pores or exacerbate skin irritation. When choosing skincare products, look for those that contain the following non-comedogenic ingredients:

Aloe vera
Allantoin
Witch hazel
Green tea extract (catechins)
Niacinamide
Tea tree
Vitamin C
Vitamin E
Zinc

Spot treatment of acne breakouts helps reduce acne lesion count and severity by exfoliating the skin, reducing inflammation, and killing bacterial overgrowth. Popular topical therapies, which are available over-the-counter and by prescription, include:

Retinoids
Benzoyl peroxide
Salicylic acid
Azelaic acid
Sulfur
Antibiotics

Avoid wearing tight clothing; if you wear a mask, choose one made of breathable, soft materials like cotton to reduce irritation. Wash your face morning and night and after sweating, in addition to washing masks frequently, to avoid the buildup of oils, bacteria, and sweat on the skin. (2)

When to See a Dermatologist

If you experience any of the following, it's time to schedule an appointment with a dermatologist for a professional skin evaluation and advanced treatment recommendations that can better help you gain control over acne breakouts:

You continue to experience acne or frequent breakouts despite over-the-counter treatments
You have deep, painful acne, like nodules and cysts that cause scarring
Your acne is negatively affecting your mental health and self-esteem

In addition to helping you identify the underlying factors contributing to acne and recommending targeted lifestyle modifications, dermatologists can prescribe higher-potency prescription medications and perform in-office procedures that can be more effective than over-the-counter treatment options in reducing acne appearance, treating acne-related scarring, and preventing future breakouts. (5)