Hi Eric,
Your friend shouldn't worry about it too much - if he was really allergic he would be dead.  I've seen a bad reaction from  single sting and believe me it is fast and frightening.  I thought that the victim was going to die within five minutes of being stung. 
I had a death described to me by a friend whose daughter received a single sting - she died  before he had gone 500m in his car on the way to hospital.
Your friend should however under a test for sensitivity to Hymenoptera venom and ALWAYS carry an Epipen and Zyrtec tablets with him just in case.
Best regards
Roger White
Superbee bees Cyprus.

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