Skip to Content
Home > Wellness > Health Library > Erythema Nodosum
Erythema nodosum (say "air-uh-THEE-muh noh-DOH-sum") is a condition in which red, painful bumps suddenly appear under the skin. They usually appear on the shins, but they may also appear on the forearms, thighs, and trunk.
This condition can be caused by a number of diseases and infections, or it can be caused by medicines. About half the time, there is no obvious cause.
It often starts with flu-like symptoms, such as fever and aches. Sometimes these symptoms come before the rash.
After a few days, the bumps turn bright red or purple and then fade to yellow or green, much like bruises. They usually fade completely in a few weeks.
Treatment is often not needed. But your doctor may do tests to try to find out what caused the problem.
Current as of:
February 20, 2015
William H. Blahd, Jr., MD, FACEP - Emergency Medicine & H. Michael O'Connor, MD - Emergency Medicine
To learn more about Healthwise, visit Healthwise.org.
© 1995-2015 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.
I Want To...
Our interactive Decision Points guide you through making key health decisions by combining medical information with your personal information.
You'll find Decision Points to help you answer questions about:
Get started learning more about your health!
Our Interactive Tools can help you make smart decisions for a healthier life. You'll find personal calculators and tools for health and fitness, lifestyle checkups, and pregnancy.
Feeling under the weather?
Use our interactive symptom checker to evaluate your symptoms and determine appropriate action or treatment.