Acne on the back, shoulders and chest — truncal acne — is common and frequently untreated, partly because people focus on their face and partly because it is genuinely harder to manage.
Three reasons it resists treatment:
- Thicker skin with larger sebaceous glands, which produces deeper and more inflammatory lesions
- A large surface area, so a tube of topical product intended for a face covers very little
- Access — you cannot reach much of your own back, and daily application to somewhere you cannot see is a real barrier
Truncal acne also scars readily, and scars on the back and shoulders tend to be more prominent, including keloid scarring in people prone to it.
What Works Topically
- Benzoyl peroxide body wash. The most practical option — used in the shower, it covers the whole area without needing to reach every spot. Leave it on for a minute or two before rinsing. It bleaches towels and bedding, so use white ones.
- Topical retinoid or combination gels, applied with a long-handled applicator, which is the tool that makes back application feasible.
- Salicylic acid washes for milder comedonal presentations.
Expect to use considerably more product than you would on a face, and price accordingly — larger pack sizes are usually much better value.
Why Oral Treatment Is More Often Needed
Because of the surface area and the depth of the lesions, truncal acne more frequently requires oral treatment than facial acne of similar severity. NICE recommends oral lymecycline or doxycycline alongside a topical for moderate to severe acne.
Severe or scarring truncal acne is a legitimate reason for dermatology referral and consideration of isotretinoin — and the risk of scarring is itself a reason to escalate rather than persist with treatments that are not working.
Things That Make It Worse
- Sweat left on the skin. Shower reasonably promptly after exercise.
- Tight synthetic clothing and backpack straps causing friction — a pattern sometimes called acne mechanica.
- Heavy body lotions and oils, and hair conditioner rinsed down the back. Rinse conditioner out before washing your body, not after.
- Whey protein supplements, associated with flares particularly in young men doing resistance training. If your back acne started when the supplement did, that is worth testing.
What It Might Not Be
Not everything that looks like back acne is acne. Malassezia folliculitis — a yeast-driven folliculitis — produces uniform small itchy bumps, often worse in hot weather or after antibiotics, and it does not respond to acne treatment. It needs antifungal treatment instead.
The distinguishing features are the itch and the uniformity of the bumps. If treatment for acne is doing nothing and the rash itches, mention this specifically to a GP.
Get Someone to Look
The practical problem underneath all of this is that you cannot see your own back. Ask someone to photograph it periodically in consistent lighting, both to apply treatment properly and to judge whether anything is improving. Without that, you are treating blind and guessing at progress.