What should you know about bursitis and cellulitis?

Bursae are small fluid-filled sacs that cushion movement near joints. Repeated pressure, a knock, or overuse can inflame one, causing local swelling and pain that often worsens with movement or pressure. Cellulitis affects the skin and tissue beneath it; the area may be red, hot, swollen, tender, and gradually expand.

The conditions can overlap in appearance, particularly near an elbow or knee. A break in the skin, ulcer, insect bite, or [Athlete's Foot](/conditions/athletes-foot/) can provide an entry point for infection. A person with [Type 2 Diabetes](/conditions/type-2-diabetes/) may need earlier assessment for a foot or leg problem.

Rest the affected joint, avoid leaning on it, and use a wrapped cool pack for short periods if that is comfortable. Keep any cut clean and covered, and do not squeeze a swollen area or share towels. Marking the edge of redness can help show whether it is spreading, but it does not replace medical review.

A clinician may examine the joint and skin, and may recommend treatment for infection or inflammation. Take prescribed antibiotics exactly as directed and do not use leftover antibiotics. Protect feet from cracks and treat fungal skin problems with professional guidance.

Seek same-day medical advice for rapidly spreading redness, increasing warmth, severe pain, pus, reduced joint movement, or [Fever](/symptoms/fever/). Emergency help is needed for confusion, collapse, difficulty breathing, or a rapidly worsening illness because severe infection can progress to [Sepsis](/conditions/sepsis/).

Ask whether the swelling is in the skin, bursa, joint, or more than one structure; whether fluid testing or imaging is needed; and which activity, dressing, or medicine is appropriate. Report diabetes, immune problems, recent wounds, and recent antibiotics.