Triggers of Hives
When hives occur, they can be very frustrating to patients. The first step is to make sure there is not an underlying cause or trigger. Some of the more common triggers are listed here:
Certain foods (particularly peanuts, eggs, nuts, and shellfish)
Medications such as antibiotics (especially penicillin and sulfa), aspirin, and ibuprofen
Insect bites or stings
Physical causes such as exercise, cold, heat, or sun exposure
Latex
Blood transfusions
Bacterial infections, including urinary tract infections and strep throat
Viral infections, including the common cold, infectious mononucleosis, and hepatitis (this is the most common underlying cause in children)
Pet dander
Pollen
Some plants such as poison ivy and poison oak
Certain contact allergens such as fragrance (though these are more likely to cause contact dermatitis)
A good place to start is by reviewing how and when the hives started, if any new stimuli are present, and if avoidance of anything makes the hives better. Sometimes when the cause is not obvious, allergy testing may be appropriate. If an underlying trigger is found, avoidance of the trigger is the most important aspect to treatment.