What should you know about infected mosquito bite cellulitis?

A mosquito bite breaks the skin barrier when it is scratched. Bacteria can then enter and cause cellulitis, an infection of deeper skin and nearby soft tissue. The affected area may become increasingly red, hot, swollen, sore, and tight; the edge can expand rather than staying limited to the original bite. Itching from the bite may occur, but expanding warmth and pain are more concerning for cellulitis. Athlete's foot, diabetes, or another break in the skin can increase the need for careful assessment.

Contact a clinician promptly if redness is enlarging or pain and warmth are increasing. Keep the area clean, avoid scratching, and mark the outer edge of redness with a pen so you can tell whether it is spreading. Rest the affected limb and raise it when practical to reduce swelling. Do not rely on antihistamines or creams alone when the skin is expanding, hot, or painful; a clinician may prescribe an antibiotic and review your response.

Seek urgent care for fever, rapidly spreading redness, severe pain, blistering, numbness, dizziness, confusion, or unusual drowsiness. Emergency help is needed if you feel faint, have trouble breathing, or become severely unwell, because a serious infection such as sepsis can affect the whole body. People with diabetes or reduced immunity should seek advice early, even when the skin changes seem limited.

Ask whether the bite has led to cellulitis, which treatment is suitable, how soon improvement should begin, and what to do if the redness passes the marked edge. Tell the clinician about fever, allergies, diabetes, immune problems, recent antibiotics, and any foot or skin infection.