This article is from the Children Allergies and Asthma FAQ, by Eileen Kupstas Soo firstname.lastname@example.org with numerous contributions by others.
If you don't know whether you're allergic, remove any insect parts
left behind to eliminate excess venom or possibility of infection
as soon as possible. The site of the sting should be washed
thoroughly. Ice (*not* heat) may help with swelling and pain.
Analgesics like aspirin can help with this as well. Oral
antihistamine and calamine lotion can help control the itching.
Medical care is needed in the case of toxic or allergic reactions.
If you aren't sure what kind of reaction you're going to have, have
someone monitor your condition and be prepared to get you quickly
to a doctor or emergency room. You probably should *not* drive
yourself unless it's unavoidable since allergic reactions may
involve sudden unconsciousness.
If you've had an allergic reaction before, you should assume that
you will again. Wear a Medic Alert bracelet or medallion describing
your condition. If the sting is on an arm or leg, place a tourniquet
between it and the heart to keep the amount of venom in the blood as
low as possible. The tourniquet should be loosened every ten minutes
or so to allow circulation. If possible, apply a cold pack. Having
suffered an allergic reaction before, you should have your handy dandy
bee sting kit with you and should give yourself a shot of epinephrine
(adrenaline). Then call 911 and get yourself to the hospital
(the epinephrine wears off after 20 minutes or so).
Antihistamines can help deal with itching and other
symptoms after the victim's condition is stabilized, but are not an
effective emergency treatment. Other steps which may be necessary
(but should probably be administered by medical personnel) include
adrenal steroids (cortisones), intravenous fluids, oxygen, and even
a tracheotomy (an opening in the windpipe) in the case of acute shock
or airway closure.