This blood test is used to determine if a person has an allergic reaction to Penicillin G.  Penicillin is an antibiotic which is commonly prescribed for treating various infections.  Symptoms of an allergic reaction typically begin within an hour of taking the drug but may take longer in some people.  Common symptoms include skin rash, hives, itching, fever, shortness of breath, runny nose and itchy or watery eyes.  People with a more severe reaction may experience anaphylaxis which includes symptoms such as tightening of the throat and airways, drop in blood pressure, dizziness, lightheadedness, nausea, vomiting, diarrhea, rapid pulse and loss of consciousness.  People experiencing signs of anaphylaxis should see a doctor immediately.

There are more than one type of penicillin and people who are allergic to one type may or may not be allergic to other types as well.  Penicillin G is one of the most commonly prescribed forms of penicillin.  It is typically taken intravenously because it is less resistant to stomach acid.