Dermatology
What Causes Acne?
Last reviewed: May 2026 · Haute MD Editorial Team
Acne is caused by a combination of excess sebum (oil) production, clogged hair follicles, bacterial overgrowth (primarily Cutibacterium acnes), and inflammation. Hormonal fluctuations — particularly androgens — are a major driver, which is why acne is common during puberty, menstrual cycles, pregnancy, and perimenopause.
Types of acne lesions
Acne presents as comedones (blackheads and whiteheads), papules, pustules, nodules, and cysts. Cystic and nodular acne are the most severe forms and are most likely to cause permanent scarring.
What triggers acne flares?
Common triggers include hormonal changes, stress, certain medications (steroids, lithium, some birth control pills), high-glycemic diets, dairy consumption in some individuals, and comedogenic skincare or hair products. Contrary to popular belief, chocolate and greasy food have not been conclusively proven to cause acne.
When does acne require a dermatologist?
See a dermatologist if acne is not responding to over-the-counter benzoyl peroxide or salicylic acid after 8-12 weeks, if you are developing nodules or cysts, if acne is causing scarring or significant distress, or if you need prescription treatments such as topical retinoids, antibiotics, or oral isotretinoin.
Frequently Asked Questions
Can adults get acne?
Yes. Adult acne — particularly hormonal acne in women — is increasingly common. It typically appears on the lower face, chin, and jaw and is often linked to hormonal fluctuations.
Does diet affect acne?
Research suggests that high-glycemic diets and dairy may worsen acne in some individuals, though the relationship varies by person. A dermatologist can help identify whether diet is contributing to your breakouts.
What is the difference between acne and rosacea?
Acne involves comedones and is driven by oil and bacteria. Rosacea involves facial redness, visible blood vessels, and inflammatory papules but does not cause blackheads. A dermatologist can differentiate and treat both.
Can stress cause acne?
Stress triggers hormonal changes that increase sebum production and inflammation, which can worsen existing acne. Stress is a significant aggravating factor but rarely the sole cause.
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