Diagnosing the difference between an allergy and intolerance is difficult because the two conditions can cause similar symptoms. Citric acid is an additive in many processed foods and beverages that is used as natural preservative and to add a sour taste to the product, according to Science Daily. It’s an organic acid that is found primarily in citrus fruits. If you experience adverse reactions after consuming citric acid, you will also develop the same symptom after eating citrus fruits. Talk with your doctor for a proper diagnosis and to distinguish between an allergy and intolerance.

A food allergy is an overreaction of the immune system to the proteins found in citric acid. When you consume a product containing citric acid, your body doesn’t recognize the proteins and begins to defend itself. Medline Plus states that the immune system begins to make specific antibodies called IgE, or immunoglobulin E, antibodies, which are intended to fight off the invading proteins. When IgE antibodies enter the blood stream, mast cells begin to generate histamine. Histamine is a chemical in the body that helps to ward off infections, but during an allergic reaction, high levels are released in soft tissue, causing inflammation.

Citric acid intolerance differs from an allergy because it does not affect the immune system, according to MayoClinic.com. An intolerance toward citric acid is a malfunction of the digestive tract. The American College of Gastroenterology states that food intolerances are caused by an inability of the small intestines to properly digest certain sugars and proteins found in foods. This causes the sugars and proteins to remain in a complex state and cannot be absorbed by the gut. The digestive system becomes irritated, inflamed and swollen, which leads to common citric acid intolerance symptoms.

The most common symptoms between the two conditions are related to the gastrointestinal tract. Shortly after consuming citric acid, you may develop nausea, vomiting, stomach cramping, stomach pain, diarrhea, blood in your stool and foul-smelling stools. If you are allergic to citric acid, you will develop other symptoms aside from the digestive system. Medline Plus states that common food-related allergy symptoms include asthma, wheezing, shortness of breath, nasal congestion, a runny nose, skin reactions, hives, eczema and facial swelling. You need to call your doctor if you develop symptoms related to an allergy.

An allergist is the most qualified medical doctor to diagnose your condition. An allergist, accompanied by your primary physician will work together to perform various tests on your blood, skin and stool. Allergy tests are used to identify the presence of IgE antibodies in your body when exposed to citric acid. Other tests to diagnose intolerance look for complex sugars and proteins in your stools.