Causes of Acne on Arms and Trunk

Pathophysiology of Truncal and Arm Acne

Acne vulgaris is a chronic inflammatory skin disease affecting the pilosebaceous unit (hair follicle and sebaceous gland) that can appear on both the face and trunk, according to the American Academy of Dermatology 1
The pilosebaceous units on the trunk and arms contain sebaceous glands that can become inflamed, leading to acne formation, as reported by the American Academy of Dermatology 2
Excess sebum production, a key contributing factor, is influenced by hormonal stimuli that stimulate sebaceous glands to produce more oil, as noted by the American Academy of Dermatology 1

Friction and occlusion, such as from tight clothing, backpacks, or sports equipment, can trap sweat and oils against the skin, contributing to acne on the trunk and arms, as stated by the Annals of Oncology 3
Excessive washing with hot water can irritate skin and worsen acne on arms and trunk, according to the Annals of Oncology 3, 4
Skin irritants, such as solvents, disinfectants, or over-the-counter anti-acne medications, can exacerbate acne, as reported by the Annals of Oncology 3, 5
Sun exposure can worsen acne on exposed areas of the trunk and arms, as noted by the Annals of Oncology 3
Medication side effects, including certain anticancer agents (EGFR inhibitors, MEK inhibitors), can cause acneiform eruptions on the trunk and arms, as stated by the Annals of Oncology 3, 6

Avoiding frequent washing with hot water can help prevent acne on the trunk and arms, as recommended by the Annals of Oncology 3
Avoiding skin irritants, such as harsh soaps or anti-acne products not prescribed by a dermatologist, can help prevent acne, according to the Annals of Oncology 3
Using alcohol-free moisturizing creams containing 5-10% urea can help prevent acne, as suggested by the Annals of Oncology 3
Applying sunscreen (SPF 15 or higher) to exposed areas of the body can help prevent acne, as recommended by the Annals of Oncology 3
Wearing loose-fitting, breathable clothing can help reduce friction and occlusion, preventing acne on the trunk and arms, as stated by the Annals of Oncology 3

Topical treatments, including benzoyl peroxide, retinoids, and antibiotics, are first-line for mild to moderate truncal acne, as recommended by the American Academy of Dermatology 1