Erythema Nodosum
Tender red lumps under the skin, usually on the shins
Quick Facts
- Type: Inflammatory skin condition
- Typical site: Front of the lower legs (shins)
- Common triggers: Infections, medications, inflammatory diseases
- Course: Usually resolves within weeks
Overview
Erythema nodosum is an inflammatory condition that produces tender, raised, red or purplish lumps in the fatty layer just beneath the skin. The lumps most often appear on the front of the lower legs, over the shins, although they can occur on the thighs, arms, or elsewhere. They are typically warm and painful to the touch.
Rather than being a disease in its own right, erythema nodosum is usually a reaction of the body to something else, such as an infection, a medication, or an underlying inflammatory condition. In many cases no specific trigger is found. The lumps usually fade over a few weeks, often changing color like a bruise as they heal, and most people recover fully.
Symptoms
The main feature is the appearance of painful lumps, but other symptoms can accompany them:
- Tender, firm, red or purplish lumps, usually on the shins
- Lumps that feel warm and are painful to touch
- Skin over the lumps that may change color, like a fading bruise, as they heal
- Aching joints, especially in the ankles and knees
- Fever and a general feeling of being unwell
- Tiredness
The lumps do not usually break open or scar. Joint aching and mild fever often occur before or alongside the skin changes.
Causes
Erythema nodosum is thought to be a hypersensitivity reaction, in which the immune system responds to a trigger by inflaming the fat layer under the skin. Common triggers include:
- Infections: Streptococcal throat infection is a frequent cause; others include certain fungal and bacterial infections.
- Inflammatory diseases: Such as sarcoidosis and inflammatory bowel disease like ulcerative colitis and Crohn's disease.
- Medications: Including some antibiotics and oral contraceptives.
- Pregnancy.
In a substantial number of cases, no specific cause is identified, and the condition is called idiopathic.
Risk Factors
- Being female, as it is more common in women
- Age between roughly 20 and 40
- A recent streptococcal or other infection
- Having an inflammatory condition such as sarcoidosis or inflammatory bowel disease
- Use of certain medications
- Pregnancy
Diagnosis
Doctors usually recognize erythema nodosum by its characteristic appearance. Because it often points to an underlying cause, testing focuses on identifying triggers:
- Physical examination: The typical tender shin lumps are often enough to suspect the diagnosis.
- Throat swab and blood tests: To check for streptococcal and other infections and for signs of inflammation.
- Chest X-ray: To look for sarcoidosis or other lung conditions.
- Skin biopsy: Occasionally done if the diagnosis is unclear, showing inflammation of the fat layer.
Treatment
Treatment addresses both the symptoms and any underlying cause:
- Treating the trigger: For example, treating an infection or adjusting a medication where appropriate.
- Rest and leg elevation: To reduce pain and swelling.
- Pain relief: Nonsteroidal anti-inflammatory drugs (NSAIDs) often help with pain and inflammation, used as advised.
- Other medications: In persistent cases, doctors may use potassium iodide or, less commonly, corticosteroids once infection has been ruled out.
Most cases resolve on their own within three to six weeks, and supportive care is often all that is needed.
Even though the skin lumps usually heal without scarring, finding and addressing any underlying trigger is an important part of treatment. If a medication appears responsible, a doctor can advise whether it should be changed. If an infection or an inflammatory condition is found, treating it not only helps the skin but also addresses a potentially more important health issue. Repeated or long-lasting episodes are a particular reason to look carefully for an underlying cause.
Prevention
- There is no specific way to prevent erythema nodosum
- Promptly treating infections such as strep throat may reduce the chance of a reaction
- Managing any underlying condition such as inflammatory bowel disease or sarcoidosis
- Telling your doctor about new lumps after starting a medication
When to See a Doctor
See a doctor if you develop tender red lumps on your shins, especially with fever or joint pain, so the cause can be found. Seek prompt medical care if you have:
- A high fever or feel very unwell
- Lumps that break open, ooze, or do not heal
- Significant breathing problems or chest symptoms
- Recurrent episodes, which may point to an underlying condition needing treatment
Frequently Asked Questions
What does erythema nodosum look like?
It appears as tender, firm, red or purplish lumps, usually on the front of the lower legs over the shins. The lumps are warm and painful to touch and often change color like a fading bruise as they heal, without breaking open or scarring.
What causes erythema nodosum?
It is usually a reaction to an underlying trigger, such as a streptococcal or other infection, inflammatory diseases like sarcoidosis or inflammatory bowel disease, certain medications, or pregnancy. In many cases no specific cause is found.
How long does erythema nodosum last?
Most cases clear up on their own within about three to six weeks. The lumps gradually fade, often passing through bruise-like color changes, and supportive care such as rest, leg elevation, and pain relief is usually enough.
Is erythema nodosum serious?
The skin condition itself is usually not dangerous and tends to heal without scarring. However, because it can signal an underlying illness, it is worth seeing a doctor to look for a treatable cause, especially if you have fever, breathing problems, or repeated episodes.
Does erythema nodosum need special treatment?
Often it just needs rest, leg elevation, and anti-inflammatory pain relief while it heals, along with treating any underlying trigger. Persistent cases may need additional medications under a doctor's guidance.
References
- MedlinePlus, U.S. National Library of Medicine. Erythema nodosum.
- Mayo Clinic. Erythema nodosum.
- American Academy of Dermatology. Skin inflammation.
- National Organization for Rare Disorders (NORD). Erythema nodosum.