Cystic acne on the back: causes and treatment

Cystic back acne is the deep, painful kind: lumps under the skin of the back that hurt when you lean against a chair, last for days, and often leave a mark. It is severe acne, and it behaves differently from the small pimples and blackheads that a body wash can handle. This guide explains what the lumps are, why they need a dermatologist, which treatments work, how to limit scars while you wait for an appointment, and which back lumps are something other than acne. It is part of Skinli's guide to body acne.

Skinli gives general education, and it is not a doctor. If you have deep, painful lumps on your back, the most useful step you can take is to book a dermatologist.

What cystic back acne is

The American Academy of Dermatology (AAD) explains how these lumps form: "When a pore fills with enough excess oil, dead skin cells, and bacteria to cause inflammation (swelling) that goes deep into the skin, an acne nodule or cyst develops." It separates the two by feel. A cyst contains pus, and a nodule has none, so "they feel harder to the touch." Both are tender or painful because they sit deep in the skin.

NIAMS, part of the US National Institutes of Health, calls deep, painful, pus-filled lumps "severe nodular acne (sometimes called cystic acne)." The AAD says isotretinoin is prescribed for this type of acne, whose lumps "can be the size of a pencil eraser or larger."

On the back, these lumps usually sit among other acne. The NHS lists nodules and cysts as "larger lumps under your skin" that "may join together and can be painful," and says a person can have more than one type of spot at once.

Why the back matters

Acne on the back tends to be deeper than acne on the face. A 2026 review of acne on the trunk, the chest, back and shoulders, says trunk skin has a thicker outer layer, and that acne there is mostly the red, swollen kind, "with common lesions including papules, pustules, nodules, and cysts." It says acne on the trunk is more likely to scar, "particularly on the shoulders and upper chest," and that dark marks after acne last longer there.

A small 2019 study followed 23 people with severe nodular acne on the back for 4 weeks without treatment, using photos twice a week. Most were men, with an average age of 25. Two findings stand out:

• New nodules kept appearing, at 3.1 per person per week, and each one lasted 4.9 days on average.
• After 4 weeks, 77.3% of the nodules present at the start had turned into sunken scars.

The study was small, and four of its six authors worked at Galderma R&D, a drug company's research department. Its message matches the AAD's: deep acne on the back scars fast, so treatment should start early.

What causes it

The AAD says a family history raises your risk: "If one of your parents or another close blood relative had deep, painful pimples, you have a greater risk of developing this type of acne." Other causes and triggers:

• Hormones. NIAMS says androgens, male sex hormones that rise in both boys and girls at puberty, make oil glands larger and more active.
• Medicines. NIAMS names medicines that contain hormones, corticosteroids or lithium.
• Anabolic steroids. The UK's NICE acne guideline tells doctors to consider specialist care when a medicine, "including self-administered anabolic steroids," may be driving acne. The 2026 trunk review says a rare, severe form called acne conglobata, with linked abscesses on the shoulders, chest, upper arms and buttocks, has been tied to anabolic steroid use in some cases.
• Polycystic ovary syndrome. The AAD says women with this hormone condition often have acne along with other signs, such as hair loss on the head, extra facial hair or irregular periods.

Why it needs a dermatologist

The AAD's severe acne page is direct: "You cannot clear it with acne treatment that you buy at the store. To see clearing, you either have to wait it out or see a dermatologist. Waiting out severe acne can take years." Its back acne page says anyone with deep, painful acne on the back "will need a dermatologist's help."

The UK's NICE guideline tells doctors to refer people with nodulo-cystic acne, meaning acne with nodules and cysts, to a team led by a consultant dermatologist.

What a dermatologist can use

The AAD's 2024 acne guideline and its patient pages describe these treatments:

Treatment	What it does	What the sources say
Antibiotic pills plus a medicine on the skin	Calms redness and swelling, and targets bacteria and clogged pores	Often the first treatment for severe acne, the AAD says. NICE says the pill part "may be effective in treating affected areas that are difficult to reach with topical treatment (such as the back)"
Isotretinoin	Works on all four causes of acne: bacteria, clogged pores, oil and swelling	Strongly recommended by the 2024 guideline for severe acne or acne that scars. The AAD estimates that 85% of patients see permanent clearing after one course
Hormone treatment for women	Spironolactone reduces excess oil, the AAD says	The AAD names the birth control pill and spironolactone
Steroid injection	Shrinks a large, painful lump quickly	The AAD says it "helps to quickly reduce the size and pain." The 2024 guideline lists it for larger acne lesions
Incision and drainage	Drains a large cyst that medicine cannot clear	Done in a medical office. The AAD warns never to drain a cyst at home

Isotretinoin needs close medical supervision. In the United States, the AAD says, people who take it enroll in a safety program run by the FDA, see their dermatologist every 30 days, and, if they can become pregnant, take pregnancy tests and avoid pregnancy. Skinli's Accutane guide explains the medicine in depth, and severe acne and when to see a dermatologist explains the visit.

What to do while you wait for an appointment

These steps limit damage while you wait for treatment:

1. Leave the lumps alone. The AAD says popping at home often pushes what is inside a pimple deeper into the skin, which increases inflammation and can cause scars and pain. It also warns of infection from bacteria on your hands.
2. Use ice for pain. The AAD's advice for a painful nodule or cyst is: "Relieve pain with ice. Some acne can be painful, especially nodules and cysts. Ice reduces the inflammation."
3. Keep up a gentle routine. A benzoyl peroxide body wash can treat the smaller pimples around the lumps. See acne body wash.
4. Take pressure off. Loose clothes and a bag carried in the hand spare the back from rubbing, which the AAD links to back acne flares.
5. Take photos. Pictures of your back taken each week show the dermatologist how often new lumps appear. How to track acne with progress photos explains how to take them the same way each time.

Other lumps on the back

A single lump, or lumps in skin folds, may be a different condition:

• Epidermoid cyst. MedlinePlus describes a closed sac under the skin "filled with dead skin cells," usually a small lump that does not hurt, often with "a tiny hole or pit in the center," found on the face, neck and trunk. It needs treatment only if it becomes red, sore or infected. MedlinePlus adds that some skin cancers can look like a cystic lump, so any new lump should be examined.
• Hidradenitis suppurativa. The AAD says this condition causes pimple-like bumps or deep, acne-like cysts where skin touches skin, such as the underarm, groin, buttocks or upper thighs. The AAD says a few people have developed it on the back, and that this is rare.
• Boils. The NHS describes a boil as "a hard and painful lump that fills with pus." It says to see a GP if a boil lasts 2 weeks, and to get an urgent appointment if the skin around it is hot, painful and swollen or you feel hot, cold or shivery. Body acne or folliculitis explains infected hair follicles.

Scars

Scars are the main reason to act early. The AAD says you may lower your risk of scars by treating acne when you first notice it and by never picking or squeezing it. The back acne scars guide covers what can be done for scars that have already formed, and cystic acne covers deep acne anywhere on the body.

When to see a doctor

Book a dermatologist if you have any deep, painful lump on your back, if lumps keep coming back, or if you see scars. Get medical care the same day if painful, open, bleeding sores appear suddenly. The 2026 trunk review describes this as acne fulminans, a rare, severe form seen mostly in males, and NICE says people with it should be referred to a hospital skin team the same day. Skinli's free acne plan is built for acne on the face from a photo and cannot assess the back.