An allergic reaction is an overreaction by your body to a substance that is normally considered harmless. Any of a wide range of symptoms may or may not occur following an allergic reaction to a sting. In the most serious cases, anaphylaxis, an extremely great sensitivity, can also occur. These symptoms can occur immediately but usually start within 10 to 20 minutes. Subsequent stings to people who have had severe anaphylactic symptoms are likely to cause the same symptoms again.
Death can result from circulatory collapse and respiratory obstruction.
Normally, these persons show progressive worsening in their reactions to stings. In other words, it is extremely rare for someone to have a life-threatening reaction to a sting without some reaction to previous stings. Bee stings are common and painful, but rarely fatal. Far more fatalities per year are associated with being struck by lightening than by being stung by bees. Following a sting, the majority of even the allergic reactions are not serious and are usually self-limiting.