Use ice or cool water for 10 to 30 minutes after the sting. This blunts the body's allergic response. An antihistamine such as Benadryl, taken by mouth, can give some added relief, and help prevent the reaction from spreading. A shake lotion such as calamine can be helpful. A paste made of baking soda and water can have a similar effect.
Topical hydrocortisone can also provide some symptomatic relief.
Give acetaminophen or ibuprofen for systemic pain relief. In most cases, the pain has largely disappeared within 2 hours, although swelling may not be apparent until the next day. Large local reactions, larger than 3 inches in diameter, will often persist for up to a week. A physician should be consulted if the reaction continues to spread. Systemic reactions such as hives, redness, or swelling elsewhere on the body, vomiting, dizziness, hoarseness, thickened speech, or difficulty breathing, should receive prompt medical care from a physician.