Calamine lotion often reduces the itching. Ironically, either hot or cold will lessen the pain. A lengthy hot tub bath will help relieve abdominal pain that often develops after a bite. A cold pack or ice pack on the area will help relieve pain. Those sensitive to stings should avoid situations in which they might get stung.
Reactions can occur within minutes or hours.
Contact a physician. Death can result if treatment is not sought. If you have a known allergy to a certain venom, you can have a physician prescribe an emergency treatment kit which you can keep with you. Purchase a small venom extractor and keep it with you. Squashing a yellow jacket releases a chemical that causes other yellow jackets to attack.