Acne occurs when oil, dead skin cells, and bacteria build up inside hair follicles, resulting in infection and inflammation.

Although acne often develops on the face, it can affect hair follicles on other body parts, such as the chest, back, and shoulders. It is the most common skin condition in the United States.

Below, we describe what acne is and the types of acne that can develop on the shoulders. We also explore the symptoms and appearance of shoulder acne and list some treatment options.

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Pores are small openings in the skin. Each pore contains a single hair that sits inside a hair follicle. These hair follicles connect to oil-producing glands, called sebaceous glands.

Sebaceous glands secrete an oil called sebum, which carries dead skin cells to the skin’s surface.

Sometimes, sebum and skin cells form a plug within the hair follicle. This plug traps dirt and bacteria inside the skin, resulting in an infection. The infection triggers inflammation in the form of a pimple.

Two types of acne can develop on the shoulders: acne vulgaris and acne mechanica.

Acne vulgaris typically occurs when oil and dead skin cells build up and block a pore or hair follicle. The bacteria Cutibacterium acnes (C. acnes) can trigger or worsen the symptoms.

Changes in the levels of certain hormones can trigger breakouts. Below are some hormones that may influence acne vulgaris.

Testosterone

Testosterone regulates sebum production. As a result, rising testosterone levels can trigger acne breakouts.

For example, many people first experience acne during puberty, when hormone levels in the body rapidly change. People with polycystic ovary syndrome may also develop acne due to high testosterone levels.

Learn more about testosterone and its effects on the body here.

Progesterone and estrogen

The hormone progesterone can also contribute to acne. Progesterone levels peak during the luteal phase of the menstrual cycle, which begins after ovulation and ends just before a period. As a result, acne breakouts may occur around this time.

In addition, some people experience acne while using progesterone-only hormonal birth control, sometimes called the minipill.

The hormone estrogen has the opposite effect — it inhibits sebum production and shrinks the sebaceous glands.

Learn more about the menstrual cycle phases here.

Other hormones

Other hormones that can play a role in acne include:

  • Insulin and insulin growth factor 1: These promote the growth of the sebaceous glands.
  • Melanocortins: These hormones regulate oil production in sebaceous gland cells.
  • Corticotropin-releasing hormone: This stimulates testosterone production and subsequent sebum production.

Acne mechanica develops in response to physical factors such as:

  • pressure
  • friction
  • heat

These can damage the skin and trigger excess sebum production.

Some specific causes of acne mechanica include:

  • pressure or friction from a heavy backpack or purse
  • irritation from pillows or blankets made from rough or coarse fibers
  • excess heat and pressure from tight or restrictive clothing
  • excess heat and moisture from sweating, especially if a person does not immediately shower or change their clothes after physical activity

Not all acne looks or feels the same. Acne pimples vary in size, color, and severity.

Different types include:

  • Blackheads: These are small, round bumps with black spots in the centers. Each spot is oxidized sebum, not dirt.
  • Whiteheads: These are small, round bumps with white centers.
  • Papules: These are small, discolored bumps that may feel sore or tender.
  • Pustules: These are small bumps with an inflamed base and a white, pus-filled head.
  • Nodules: These are large, hard lumps deep within the skin. Nodules can be tender or painful to the touch.
  • Cysts: These are large, pus-filled lumps that may cause scarring.

Over-the-counter (OTC) topical treatments can help clear acne breakouts. Products containing the following ingredients can often be of help.

Benzoyl peroxide

Benzoyl peroxide is an antiseptic that kills C. acnes bacteria on the surface of the skin and inside hair follicles.

In 2017, a 12-week clinical trial investigated the effectiveness of this antiseptic as a treatment for acne vulgaris among 607 participants.

The researchers found that using a benzoyl peroxide cream resulted in a 72.7–75.0% reduction in inflammatory lesions, while using a placebo cream resulted in a 41.6% reduction in inflammatory lesions.

Salicylic acid

Salicylic acid is a beta-hydroxy acid that reduces sebum production and skin inflammation. It also reduces acne lesions by exfoliating the skin and removing oil, dirt, dead skin cells, and bacteria.

A small 2018 clinical trial compared the effectiveness of a salicylic acid cream with a benzoyl peroxide cream for the treatment of mild to moderate acne. The trial included 31 participants, and all applied each cream to separate sides of their faces for 28 days.

The researchers found that the 2% salicylic acid cream reduced the number of papules and pustules by 47.9% and reduced the number of noninflammatory lesions by 43.1%. These results were comparable to those of the benzoyl peroxide cream.

The researchers concluded that the two creams were similarly effective in treating acne.

Learn more about salicylic acid for acne here.

Retinoids

Retinoids are a class of chemical compounds derived from vitamin A. They increase skin cell turnover, helping to keep dead cells, oil, and bacteria out of pores. This turnover can help prevent acne from forming.

A person needs to apply a retinoid consistently to see results. The effects of retinoids will cease when treatment does.

Learn more about retinol and retinoids for acne here.

Azelaic acid

Azelaic acid exists naturally in grains, such as wheat, barley, and rye. Topical application helps decrease discoloration and swelling of the skin.

A small 2017 pilot study investigated the safety and efficacy of a 15% azelaic acid foam in treating mild acne on the torso.

The results showed that 44% of participants who applied the foam twice daily experienced a significant reduction in acne.

The following prescribed medications, which come in pill form, can help treat the underlying causes of acne.

  • Antibiotics: These can treat moderate to severe acne vulgaris, though experts warn against using them long term. Doctors typically recommend a more sustainable topical treatment, such as one containing benzoyl peroxide.
  • Contraceptives: The Food and Drug Administration (FDA) has approved the following oral contraceptives for the treatment of acne:
    • norgestimate and ethinyl estradiol (Ortho)
    • norgestimate and ethinyl estradiol (Tri-Cyclen)
    • ethinyl estradiol and norethindrone (Estrostep)
    • drospirenone and ethinyl estradiol (Yaz)
  • Hormone therapy: This involves taking medications that reduce levels of certain hormones that contribute to acne. Examples include:

Learn more about birth control options for acne here.

At-home treatments

The American Academy of Dermatology provides the following tips for managing acne:

  • washing the skin twice a day and as soon as possible after sweating
  • rinsing the skin with lukewarm water
  • avoiding harsh skin care products, such as astringents, toners, and exfoliants
  • regularly shampooing the hair
  • limiting or avoiding tanning
  • avoiding picking or popping pimples

To help prevent shoulder acne, people can try:

  • wearing lightweight, breathable clothing
  • immediately changing out of sweaty clothes
  • applying sunscreen to the shoulders in sunny weather
  • keeping the hair clean to avoid getting excess oil on the shoulders
  • avoiding using bags with shoulder straps, especially when carrying heavy items
  • avoiding scrubbing or scratching the skin, which can irritate the area and introduce dirt and bacteria into existing pimples

Shoulder acne may clear up on its own or with the help of OTC products.

A person should contact a doctor if acne persists or worsens despite home treatment, or if more than one painful acne lesion develops.

A doctor may prescribe a stronger treatment for more severe acne. Or they may refer the person to a dermatologist (a doctor specializing in treating skin conditions).

Acne occurs when oil and dead skin cells form a plug inside a pore or hair follicle. This plug traps dirt and oil beneath the skin. A bacterial infection can develop in the affected pore, leading to inflammation and swelling in the form of a pimple.

Two types of acne can develop on the shoulders: acne vulgaris and acne mechanica. The first typically develops in response to hormonal changes, while the second typically develops in response to heat, pressure, friction, or a combination of these.

Shoulder acne does not look or feel the same for everyone. Some people develop small pimples, while others with more severe acne develop pustules, nodules, or cysts. More serious acne can be extremely painful and require stronger treatments.