What is it?

Erythema Nodosum is an inflammation of the fatty layer of the skin. This inflammation causes the skin to become red, painful, and tender. Erythema nodosum is typically seen on the shins, below the knees. Also, typical lumps are inflamed and these may come and go for several weeks until they shrink and become flat. This condition goes away on its own after 6 weeks, leaving a bruised appearance on the skin. Erythema nodosum can appear on its own, or with other medical conditions such as strep throat, cat scratch disease, fungal disease, infectious mononucleosis, sarcoidosis, Behcet's disease, inflammatory bowel diseases and pregnancy. Some medications can cause erythema nodosum as well such as birth control pills and sulfa related drugs.