Question: If I was stung by a bee and just had local swelling, does that mean I am at high risk for a more severe reaction next time?
Answer: Insect stings can cause swelling that is normal and some people will have larger swellings than others. But if the swelling builds up over a period of 12 or 24 hours and becomes very large, meaning six to eight inches or larger, football size, or even the entire arm or leg, that's an extreme local swelling. It is probably an allergy and it can happen again with future stings.
But what's the chance of having an anaphylactic reaction, a systemic reaction that is the dangerous kind of reaction, like throat swelling, trouble breathing or dizziness or unconsciousness?
People who've had these allergic large swellings have a fairly low chance of having the more dangerous reaction. It certainly can happen but that chance is about five percent and that's not usually considered a high enough chance to justify a whole immunization program, although in some cases it could be considered for people who are outdoor workers or gardeners or landscapers who get stung every year and have large swellings every year and require treatment every year. They could be immunized too.
But the main reason for immunization is usually people who've had severe allergic reactions. If you've had a large swelling then the doctor might discuss with you whether to carry any medications to help counteract reactions or an epinephrine injector to help prevent or control the systemic or life threatening reactions if they should occur. But that chance is less than five percent.