Cardio is probably the most common type of exercise that people seem to be "allergic" to, but sometimes just sitting in a hot tub or getting stressed can lead to symptoms, Dr. Wolbert says. There are a few other factors that can make your body really go into overdrive and cause a reaction, too. For example, some people find that eating certain foods before or after exercising increases the risk of allergic reactions , Dr. Wolbert says. "Really, pretty much any food can cause this — there are case reports for most foods people eat," he says. Drinking alcohol or taking a non-steroidal anti-inflammatory drugs (like ibuprofen) can also trigger it. And some find that they have increased allergic reactions during their menstrual cycle, because they have increased histamine levels