Adult cellulitis: signs, treatment and when to get help

It commonly causes an enlarging area of warm, red, swollen and tender skin, often on one lower leg. The edge may be poorly defined rather than forming a neat ring. Treatment should begin promptly because the infection can spread through nearby tissues or, in severe cases, affect the whole body.

Bacteria can enter through a small break in the skin, including a crack between the toes, an ulcer, a cut or an area of eczema. The entry point may be too small to notice. Athlete's foot, persistent swelling and diabetes can make skin breaks or infection more likely, but cellulitis can occur without an obvious trigger.

Cellulitis often presents with skin redness, painful skin and swelling; fever or feeling unwell may accompany a more significant infection. Similar-looking problems include a blood clot, an allergic reaction and inflammation without infection, so an examination is needed rather than self-diagnosis.

Arrange a same-day medical assessment for a new area that is hot, painful, swollen and expanding. A clinician may mark its border, check for a wound or abscess and decide whether oral or intravenous antibiotics are appropriate. Take prescribed antibiotics exactly as directed and do not share leftover medicine.

Rest and elevate an affected limb when practical. Drink fluids unless you have been advised to restrict them, and use a suitable pain reliever if you can take it safely. Avoid squeezing, massaging or puncturing the area. Keep any wound clean and follow the dressing advice you receive.

Seek emergency care for confusion, faintness, difficulty breathing, very rapid breathing, mottled or unusually pale skin, severe weakness, or rapidly worsening illness. These can accompany sepsis and should not wait for a routine appointment.

Prompt reassessment is also needed if redness spreads despite treatment, pain becomes severe, blisters or dark areas develop, the infection is near an eye, or you cannot keep medicine down. People with reduced immunity, poor circulation or poorly controlled diabetes should mention this during assessment because it can influence monitoring and treatment.

Ask what features support cellulitis, whether there is an abscess that needs drainage, how improvement should look, and when you should return if the border keeps spreading. You can also ask how to care for the suspected entry point and whether recurrent episodes call for foot, swelling or skin-barrier management.