For most mosquito bites, wash the area gently with soap and water, then apply a cold pack or a cool, wet cloth for about 10 to 20 minutes. An over-the-counter hydrocortisone cream or calamine lotion can also help reduce itching and swelling.
Try not to scratch the bite, since broken skin can become irritated or infected. If itching is more widespread or bothersome, an oral antihistamine may help, but it should be used according to the package directions and checked with a pharmacist or doctor for children, pregnancy, or other health conditions.
Most mosquito bite reactions are mild and improve on their own within several days. Reapply the cold pack as needed, and stop using any cream that causes burning, redness, or worsening irritation. Avoid using strong heat sources or unproven home remedies, since these may damage the skin or provide little benefit.
Seek medical care if the redness keeps spreading, the area becomes very painful, pus appears, or fever develops. Emergency help is needed for trouble breathing, facial swelling, dizziness, or a severe body-wide reaction. To prevent more bites, use mosquito repellent and cover exposed skin when possible.