Contributed by Dermveda

Acne, or acne vulgaris, is one of the most common skin conditions in the world. It consists of acne lesions or pimples, including comedones, whiteheads, blackheads, cysts, and nodules and is often accompanied with redness and pain. Acne not only afflicts teenagers, but many people also continue to experience breakouts into adulthood. Some even develop acne for the first time as an adult.1 In addition to physical symptoms, acne is emotionally distressing for many and can gravely affect quality of life. Studies show that acne can profoundly impact mental health in over 50% of individuals, with significant associations with poor emotional well-being, depression, and even suicidal ideation.2-4


What Causes Acne?

Acne is usually caused by a combination of what are known as the “four pillars of acne.”5 Any individual may have acne caused by one or a combination of these various mechanisms, which is why acne treatments are targeted directly at one or more of these pillars:

  • Clogged pores
  • Increased oil production
  • Bacterial overgrowth
  • Inflammation


Clogged pores

The skin regenerates on a continual basis.  Sometimes the skin cells around the pores divide too quickly, leading to clogged pores.

Increased oil production

The oil glands in the skin (called sebaceous glands) are essential to keep the skin moisturized and to provide a protective film over the outer layer of skin. However, in some individuals, overproduction of oil (also known as sebum) is a contributor in acne. Hormones can trigger the sebaceous gland to produce more sebum. Increased sebum production is common during puberty and can spike just prior to menstruation in response to increased androgen hormones.6

Bacterial overgrowth

Our skin normally hosts thousands of bacteria that are typically in a healthy balance, referred to as the skin microbiota. However, clogged pores and oily skin create the perfect environment for an unhealthy overgrowth of bacteria, with the most common culprit being bacteria called Propionibacterium acnes.7


Altogether, clogged pores, excess oil, and bacterial overgrowth lead to an inflammatory response that results in inflamed lesions, redness, and sometimes pain.

Acne Symptoms

Acne is extremely common in adolescents and young adults, and studies have estimated that over 90% of all teenagers will develop acne.1 However, although most teenagers will experience acne at some point, it is also a prevalent skin condition in adults.  

 Acne usually affects the face, but can also affect the neck, back, shoulders, and chest.  Pimples, or acne lesions, are generally divided into two groups: inflammatory lesions and non-inflammatory lesions. Inflammatory acne lesions are usually more red and painful and consist of pus-filled bumps (pustules), bright red or pink bumps (papules), and even deep painful bumps called inflammatory nodules and cysts. On the other hand, non-inflammatory acne lesions are usually flesh colored bumps, referred to as open comedones (blackheads) and closed comedones (whiteheads).

 Even when acne clears up, it can leave behind dark spots and scarring. These lasting marks are notoriously difficult to treat, highlighting the importance of using effective skin care and treatments for acne-prone skin.

 Table 1 – Lesions Commonly Seen in Acne


Type of Acne Lesion

Common Name


Open Comedone


A clogged pore that has a dilated opening on top, allowing the skin debris to oxidize and turn black.

Closed Comedone


A clogged pore that is closed with a layer of skin over the top and looks like a small flesh-colored bump.

Inflamed Papule


Small pink or red dome-shaped bump with no obvious opening that is surrounded by inflammation.



A bulging bump of skin that can appear white or yellowish because it contains dead white blood cells (referred to as pus).

Nodule and Cyst

Cystic Inflamed Nodule

A nodule is a large and painful bump that forms deep beneath the skin. It can be very painful and firm to the touch. A nodule can linger for weeks or months and harden to become a cyst or scar.

Postinflammatory Hyperpigmentation

Dark Spots

These appear as dark spots in areas where acne was previously active. These spots are more common in those with darker skin color and can take months to go away even after the acne has improved.



Risk Factors


Acne affects people of all ages. Although it is most common in adolescents around the time of puberty, even newborns can develop acne shortly after birth caused by the mother’s hormones. Unfortunately, some people continue to struggle with acne into their 40s.1, 8



High glycemic foods and cow’s milk, specifically skim milk, may worsen acne.9-11 In addition, supplementation with whey protein, such as in fitness shakes, may exacerbate acne.12, 13



Humidity, heat, and sweat can exacerbate acne, such as with exercise and sports when sweat is trapped under helmets or headbands.14



For many people, acne tends to run in families and may be related to naturally producing more skin oils.6


Hormonal Fluctuations

Hormones have a direct role on oil production and fluctuations in hormones, such as progesterone during menstrual cycles, can cause acne breakouts.11



Certain ingredients and products used on the face can clog pores and directly lead to the formation of comedones and acne.



Studies have shown that acne can flare during periods of psychological stress.15, 16


Treatment Approaches

 Treatment of acne varies from person to person and is dependent on the severity of acne, ranging from mild to moderate to severe.


Table 2 – Treatment Approaches in Acne

Pathogenic Factor in Acne

Typical Treatment Approach

Clogged pores

Normalize rate of skin cell regeneration and exfoliate to help reduce clogged pores

Increased oil production

Decrease or inhibit oil production and modify sebum profile

Bacterial overgrowth

Antibacterial agents


Reduce inflammation


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