Fact sheet

Erythema Nodosum

Tender red or purple lumps under the skin, usually on both shins, caused by inflammation in the fat layer. It’s a reaction pattern rather than a disease in itself, often set off by an infection, a medicine, pregnancy or an inflammatory condition. The lumps clear in weeks without scarring.

Quick answer: Erythema nodosum is a reaction that causes tender red lumps under the skin, usually on both shins. It can be triggered by strep throat, other infections, sarcoidosis, inflammatory bowel disease, pregnancy or medicines such as the pill, though often no cause is found. Lumps fade like bruises within 3 to 8 weeks.

How common. Uncommon: about 2 to 3 people in 10,000 a year in England. It’s more common in women and most often affects people aged 25 to 40, though it can happen at any age.

Causes. No cause is found in up to half of people. Known triggers include strep throat (the most common in children), Mycoplasma chest infections, gut infections (Yersinia, Salmonella, Campylobacter), tuberculosis, sarcoidosis, Crohn’s disease and ulcerative colitis, pregnancy, the contraceptive pill and some antibiotics. Rarer links include Behçet’s disease and lymphoma.

Löfgren’s syndrome. A form of sarcoidosis that combines erythema nodosum, swollen ankles, fever and swollen glands in the chest seen on X-ray. It usually settles on its own within months to 2 years.

Symptoms. Firm, smooth, tender lumps 2 to 6 cm across, usually on both shins, sometimes thighs or forearms. They’re often easier to feel than see, and fade over weeks like bruises, going purple, yellow then brown. Fever, tiredness and aching, swollen ankles, knees or wrists often come first or alongside.

Look-alikes. Cellulitis (usually one leg, spreading, hot), bruises, insect bites, inflamed surface veins, and rarer types of fat or blood vessel inflammation, some of which ulcerate.

How it’s diagnosed. From the look of the lumps. Then the hunt for a cause: blood tests (blood count, inflammation markers, strep antibodies), a throat swab, a chest X-ray, and depending on your story, a pregnancy test, stool tests or a TB test. A skin biopsy is only needed if the picture isn’t clear.

The erythema nodosum ladder

The lumps settle on their own. Finding and treating the trigger matters most.

  1. Step 1 · Self-careRest, raise your legs and use compressionPut your feet up when sitting, avoid long spells standing or running, and try a cool damp cloth or support stockings.
    Works
    Eases pain and swelling; no trials
    Cost
    Free to about $20–40 for stockings
    How long
    Until lumps fade
    Watch for
    Stockings shouldn’t be tight enough to hurt.

    Legs up, feet up, lumps down.

  2. Step 2 · PharmacyAnti-inflammatory painkillers (ibuprofen or naproxen)Regularly for a week or two for pain and joint aches.
    Works
    Standard first-line pain relief; little trial evidence
    Cost
    About $5–15 a pack
    How long
    Days to weeks
    Watch for
    Avoid with Crohn’s disease or colitis unless your doctor says otherwise. Not in later pregnancy.

    Takes the edge off while the trigger is found.

  3. Step 3 · GPTreat the triggerAntibiotics for strep throat or another infection, or stopping a suspect medicine (only with your GP’s advice).
    Works
    Clearing the trigger usually lets the lumps settle and helps stop them coming back
    Cost
    Varies
    How long
    Varies
    Watch for
    Don’t stop the pill or another prescribed medicine without talking to your GP.

    Fix the cause, and the skin follows.

  4. Step 4 · Specialist or GPColchicine, potassium iodide or steroid tabletsFor lumps that keep coming back or don’t settle. Steroids only once infections such as TB are ruled out.
    Works
    Small studies and experience; steroids work quickly but can mask an infection
    Cost
    Varies
    How long
    Weeks
    Watch for
    Steroid side effects: raised blood sugar, mood and sleep changes.

    Strong medicine once the detective work is done.

Costs are rough Australian prices in November 2026 and vary by pharmacy and provider. PBS co-payment: $25, or $7.70 with a concession card. Results are typical figures from trials, not promises.

What you can do

See your GP if

See a doctor the same day for a hot, red, spreading area on one leg, high fever or feeling very unwell, breathlessness, a cough with blood, night sweats and weight loss, or bloody diarrhoea.

Outlook. The lumps clear in 3 to 8 weeks without scarring, though aching legs and joints can last longer. About 1 in 3 people have another episode, and a few have lumps that keep recurring for months, which usually prompts a fresh look for a cause.

Common questions

What causes erythema nodosum?

It’s a reaction to a trigger: commonly strep throat, other infections, sarcoidosis, Crohn’s disease or ulcerative colitis, pregnancy, the contraceptive pill or some antibiotics. In up to half of people no cause is found.

Is erythema nodosum serious?

The lumps themselves are harmless and clear without scarring. It matters because it can be the first sign of something that needs treating, such as an infection, sarcoidosis or inflammatory bowel disease.

How long does erythema nodosum last?

The lumps usually fade within 3 to 8 weeks, looking like bruises as they go. Leg aches and joint pain can last a few weeks longer.

Is erythema nodosum contagious?

No. The lumps can’t spread to other people, although an infection that triggered them, like strep throat, can.

What tests are done for erythema nodosum?

Usually blood tests, a throat swab and a chest X-ray, plus other tests depending on your symptoms, such as a stool test, pregnancy test or TB test. A biopsy is rarely needed.

Can erythema nodosum come back?

Yes, in about 1 in 3 people, especially if the trigger returns. Recurring lumps are a reason to look again for a cause.

Evidence and more information

Updated 8 November 2026. General education, not personal medical advice. Treatment depends on your situation, so talk to your GP or pharmacist.

Related

maladywise.com/erythema-nodosum/