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Spots on the back
Sweat, friction and occlusion: the back plays by its own rules, different from the face.
The back and shoulders have a high density of sebaceous glands and spend many hours under a layer of fabric: a combination that produces frequent inflammatory conditions, especially in those who play sport, sweat heavily or work in heavy clothing.
The first useful step is to understand what it actually is, because at least three similar-looking pictures coexist at this site. Truncal acne, with comedones alongside papules and pustules. Malassezia folliculitis, in which the lesions all look alike, are often itchy and — the decisive detail — have no blackheads. And bacterial or friction folliculitis, linked to backpacks, seating and tight clothing.
The consequence is concrete and affects many people: if there are no comedones on the trunk and the lesions all look the same, acne products will not work, and you can spend a year changing them. The distinction is made by looking, and it completely changes the treatment. For the rest, simple habits count: showering after training rather than later, not staying in a wet shirt, preferring breathable fabrics.
On the arms the picture partly changes. The density of sebaceous glands is lower, and friction and occlusion weigh more — backpacks, sleeves, gym equipment. Also, what look like spots on the arms is often keratosis pilaris: rough papules, all alike, on the outer surface, which are not acne and do not respond to acne products. Here too the distinction is made by looking.
Look for blackheads here too
It is the same criterion that applies to the face, and on the trunk it is even more useful because people cannot see their own back. Ask someone to look, or use a photo: if there are blackheads and whiteheads alongside the papules, the picture is acneic and acne treatments make sense. If instead the lesions all look alike, centred on hairs, itchy and with no comedone among them, the trail leads elsewhere — often yeast folliculitis — and needs a completely different approach. It is a photograph worth months of trial and error.
How it shows
- Papules and pustules on the back, shoulders and chest
- Worsening after physical activity or in heat
- Itching in some forms, pain in others
- Presence or absence of blackheads: the orienting detail
- Lesions where a backpack or clothing rubs
- Residual dark marks where past lesions were
How we proceed
- 1Dermatological visit: appearance of the lesions and presence of comedones
- 2Distinction between truncal acne and folliculitis
- 3Therapy based on the identified picture, not on the site
- 4Review of habits: sweat, fabrics, friction, post-sport showering
- 5Assessment of pigmentary aftermath as lesions resolve
Available treatments
- Dermatology visit
- Identification of the form
- Therapy targeted at the cause
- Scheduled follow-up
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Frequently asked questions
Why do I only get them after the gym?+
Because sweat, heat and friction with technical clothing create for a few hours the ideal environment for follicular inflammation, especially if you stay in a wet shirt after training. The most effective measure is mundane and almost nobody applies it: change and wash as soon as you finish, not after the journey home. In people with a predisposition, this change alone visibly reduces frequency.
Marks are left: can they be removed?+
Those left on the trunk after lesions are usually post-inflammatory hyperpigmentation, not scars: they tend to fade over time, more slowly in darker skin types and far more slowly if the area is exposed to the sun unprotected. The most useful rule is that they lighten only if new ones do not form meanwhile, so controlling active lesions comes before treating the marks.
Should I use harsh cleansers?+
No, and they often make things worse. Strongly degreasing cleansers and abrasive sponges damage the skin barrier and can increase inflammation, starting a cycle of washing more and being worse. On the back, where the skin is thick, the temptation to scrub is strong: effective cleansing is instead regular and gentle, and the real work is done by therapy aimed at the right picture.
Related reading
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