DefinitionErythema nodosum is the name given to extremely tender lumps on the legs and sometimes the arms. They are caused by inflammation of the fat beneath the skin. The bumps look like bruises. They change color in the same way, from pink to blue to brown.
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CausesErythema nodosum is thought to be a type of allergic reaction. It may be caused by:
- Infections from a:
- Inflammatory conditions
- Sulfa drugs and some other antibiotics
- Birth control pills
- Leukotriene modifiers
- Proton pump inhibitors
Risk FactorsThis condition is rare. It is more common in females and young adults aged 20-30 years old. Having any of the causes listed above will only slightly increase your risk of the disorder.The risk factor for erythema nodosum is genetics.
- Very tender, deep lumps, like bruises,
- Usually located on your shins
- May also appear on the forearms, trunk, neck, and head
- Associated joint pain and fever and redness around the eyes
DiagnosisYou will be asked about your symptoms and medical history. A physical exam will be done, which may diagnose the problem based on a visual exam. You may be referred to a doctor that focuses on skin problems or infectious diseases.Your bodily fluids and cells may be tested. This can be done with:
- Blood and urine samples
- PPD skin test for tuberculosis
- Biopsy of a lesion
TreatmentIf a cause can be identified, it will be treated. For the nodules themselves, pain relief is all that is needed. They tend to resolve on their own in about six weeks. They will not cause scarring. Treatment options include the following:
Pain ReliefPain relief includes:
- Bed rest and elevation of legs
- Wet compresses
- Aspirin, except in children
- Nonsteroidal anti-inflammatory drugs
- Potassium iodide
Steroid TreatmentThis may be necessary in severe cases.
PreventionSome of the infectious causes can be avoided by practicing good hygiene, which includes:
- Washing your hands often
- Not sharing food, drinks, or utensils
American Academy of Dermatology
Family Doctor—American Academy of Family Physicians
Canadian Dermatology Association
Erythema nodosum. EBSCO DynaMed website. Updated April 2, 2014. Accessed September 24, 2014.
Erythema nodosum. Better Health Channel website. Available at: http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Erythema%5Fnodosum?OpenDocument. Updated March 2014. Accessed September 24, 2014.
Requena L, Yus ES. Erythema nodosum. Dermatol Clin. 2008;26(4):425-438, v. Review.
- Reviewer: Michael Woods, MD
- Review Date: 08/2014
- Update Date: 09/24/2014