Erythema nodosum on the arms

On an arm, erythema nodosum may feel like one or more deep, sore, warm lumps with red, violet or brownish skin over them. The colour can change as the inflammation improves. These nodules are not usually open sores, and squeezing them can increase irritation.

Arm lumps have many possible explanations, including infections, insect reactions, cysts, medication reactions and other inflammatory skin conditions. A clinician considers the texture, depth, number, colour, speed of change and symptoms elsewhere before deciding whether the pattern fits erythema nodosum.

Avoid rubbing, tight sleeves and repeated pressure over the area. A cool compress and rest may make the arm more comfortable. Photographing the skin when it changes can help a clinician compare its progress. Note recent illness, new medicines, joint pain, fever, cough or digestive symptoms.

Book an assessment for new painful nodules, particularly when several appear or the skin is changing quickly. Treatment addresses discomfort and any identified trigger; prescription options, including oral corticosteroids, are considered only when clinically appropriate.

Seek prompt care if an arm becomes suddenly very swollen, hot and intensely painful, if redness spreads quickly, or if you have fever, breathing trouble, chest pain, faintness, weakness or new vision changes. Arrange a non-urgent review if a lump persists, returns or is not behaving like a settling bruise.

Does the location and feel of these lumps fit erythema nodosum? Could a medicine or recent illness be involved? Do I need a skin test or other examination? What changes should I track at home?