Allergies Food Allergies Symptoms What Is a Citrus Allergy and How Is It Diagnosed? Natural and synthetic sources of citric acid may point to the culprits By Jeanette Bradley Jeanette Bradley Jeanette Bradley is a noted food allergy advocate and author of the cookbook, "Food Allergy Kitchen Wizardry: 125 Recipes for People with Allergies" Learn about our editorial process Updated on June 02, 2022 Medically reviewed by Jurairat J. Molina, MD Medically reviewed by Jurairat J. Molina, MD Facebook Jurairat J. Molina, MD, MBA is a board-certified allergist who has been practicing in field of allergy and clinical immunology for the past two decades. Learn about our Medical Expert Board Print Verywell / Zorica Lakonic Table of Contents View All Table of Contents Causes Symptoms Sources Diagnosis Treatment When to See a Doctor Frequently Asked Questions A citrus allergy is a reaction to the acid found in citrus fruits like oranges, limes, and lemons. It is not a true allergy but a sensitivity. Citric acid is a simple molecule, and the body doesn't produce an antibody to it that would trigger an allergic reaction or show up in a traditional allergy skin test. Sensitivity to citric acid is uncommon, but some people do have allergy-like symptoms after eating citrus fruit. This article examines citrus allergy, its causes, symptoms, and diagnosis. It also looks at some of the ways citrus allergy can be treated. Causes Citrus allergy can have several different causes. Some people may be sensitive to eating citrus fruits, while others may react when touching the peels. Cross-Reactivity Some people who are sensitive to citrus have a condition called oral allergy syndrome (OAS). This condition causes you to react to proteins in food that are similar to the proteins found in pollens you are allergic to. This is known as cross-reactivity. People who are allergic to grasses, in particular, may experience OAS to citrus fruits. A 2013 study, for example, found that 39% of study participants with confirmed pollen allergies were also sensitive to citrus. Limonene allergy Limonene is a chemical present in citrus peels. Some people have a contact allergy to limonene and may develop a rash after touching a citrus peel. It is possible to be allergic to limonene but not to the fruit itself. Limonene is sometimes used commercially as a fragrance. If you react to citrus peels, it is a good idea also to avoid products that contain limonene. Systemic Allergy It is possible to have a serious, life-threatening allergic reaction to citrus fruits. Seek medical attention right away if you have symptoms of anaphylaxis, including: Trouble breathingSwelling of the throat and mouthA drop in blood pressureNausea and vomitingConfusionFlushing of the skin Symptoms of Anaphylaxis Symptoms You can experience symptoms that aren't associated with an allergy after eating citrus fruit: Mouth sores Heartburn Aggravation of acid reflux symptoms You might be having a food allergy reaction if you have the following symptoms: Itching of the mouth, tongue, and lips Rashes around the mouth Gastrointestinal symptoms, such as abdominal pain, bloating, or diarrhea Swelling of the mouth or throat Headaches Other symptoms of food allergy Many different types of food can trigger these symptoms, but they are not usually part of sensitivity to citric acid. Sources Citric acid derived from natural sources has been used as a food additive for over 100 years. It's often used to provide a sour or tart flavoring, as a preservative, or as an emulsifier. It's also commonly added to canned and jarred foods to prevent botulism. Citric acid is found in foods including: Ice creamSorbetCaramelSodaBeerWineBaked goodsProcessed sweetsPre-cut pre-packaged fruits and vegetables Citric acid in its natural form is extracted from fruits. People who react to fruit-derived citric acid are allergic to the fruit, not citric acid itself. Citric acid can also be synthesized commercially. If you're sensitive to the fruit or substances from this process, those may be what's triggering your reaction. Mold or Corn Allergy Citric acid can be synthetically produced using a type of mold called Aspergillus niger, a safe strain of black mold. It's much cheaper to produce it this way than to use the natural version. In the manufacturing process, the mold culture is fed sugar solutions, which are often derived from corn. This is often the source of citric acid used as a food additive in many processed foods. It's not unusual to have an allergy or a sensitivity to mold or corn, and in fact, many people who react to foods containing citric acid may actually be allergic to the mold or the corn used to produce the acid. If you have an allergy or sensitivity to airborne mold or mold found in the environment, you may also react to mold in or on the foods you eat. If you're allergic to corn, you may be sensitive to the tiny amount of corn that's left in citric acid during the manufacturing process. An allergist can determine if you have an allergy to mold or corn by using a skin-prick test, but to determine if you're also sensitive to mold in foods, you'll need to do an elimination diet and supervised oral food challenge. Diagnosis Your healthcare provider may want you to try an elimination test to diagnose citrus sensitivity. During this test, you eliminate citrus fruits from your diet for two weeks, then you gradually add them back to see if you react. You can also be diagnosed with a supervised food challenge. This test is done in your healthcare provider's office. You are exposed to citrus under medical supervision during the test and are watched for an allergic reaction. Treatment The best way to treat a citrus sensitivity is to avoid citrus fruits. You will also need to avoid products that contain citrus. People who experience severe reactions and are at risk of anaphylaxis should carry an EpiPen (epinephrine). It is important to keep your EpiPen with you at all times in case you experience a severe allergic reaction. If your allergy is mild, you can try taking antihistamines. This may help reduce symptoms like itching in the mouth. If you have a skin allergy, topical cortisone can also help. Citrus sensitivity can affect both adults and children. Children and young adults who have a pollen allergy or asthma may be more prone to experiencing sensitivity to citrus. When to See a Doctor You should see a healthcare provider any time you have an allergic reaction, even a mild one. It is important to undergo testing to know what you are allergic to and what foods you need to avoid. Serious allergic reactions involve swelling of the airways and trouble breathing. If you experience those symptoms, seek out emergency medical treatment. Summary Citrus allergy is not a true allergy but rather a sensitivity to components of citrus fruit. Some people are sensitive to citrus because it contains proteins similar to those in airborne pollens. It is also possible to be allergic to the chemical found in citrus peels. Most people sensitive to citrus have a mild reaction, but it is also possible to have a life-threatening anaphylactic reaction. If this happens, seek medical care at once. An allergist can confirm whether or not you are sensitive to citrus. If you are, it's best to avoid citrus fruits and products that contain citric acid. A Word From Verywell Citric acid itself doesn't cause allergic reactions, but you may be sensitive to other components of citrus fruits. Even if your reaction is mild, such as itching inside your mouth, you should ask a healthcare provider about allergy testing. Any allergic reaction can be dangerous, and it is possible your response was caused by something other than citrus. Testing can confirm what you are sensitive to so you will know what to avoid in the future. Frequently Asked Questions Can you develop a citrus allergy later in life? It is possible to develop a sensitivity to citrus later in life. This is true even if you have been eating citrus fruits for years. Talk to your healthcare provider if you suddenly experience itching of the mouth or lips or any other allergy symptoms when eating citrus fruits. Can you be allergic to citrus but not citric acid? Citric acid is not an allergen. If you are sensitive to citrus, you are probably responding to some other fruit component. Many people react to citrus because it contains proteins similar to those found in airborne pollens. What is the most common fruit allergy? Fruit allergies, like milk, eggs, peanuts, and shellfish, are less common than other allergies. The most common fruit allergies are apple, peach, and kiwi. Most fruit allergies cause reactions that are confined to the mouth. However, it is also possible to have an anaphylactic reaction to a fruit you are allergic to. 7 Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Iorio RA, Del Duca S, Calamelli E, et al. Citrus allergy from pollen to clinical symptoms. PLoS One. 2013;8(1):e53680. doi:10.1371/journal.pone.0053680 Valenta R, Hochwallner H, Linhart B, Pahr S. Food allergies: the basics. Gastroenterology. 2015;148(6):1120-31.e4. doi:10.1053/j.gastro.2015.02.006 National Center for Biotechnology Information. Citric acid, CID=311. PubChem Database. 2020. Tarkhashvili N, Chokheli M, Chubinidze M, et al. Regional variations in home canning practices and the risk of foodborne botulism in the Republic of Georgia, 2003. J Food Prot. 2015;78(4):746-50. doi:10.4315/0362-028X.JFP-14-533 Ronholm J, Lau F, Banerjee SK. Emerging seafood preservation techniques to extend freshness and minimize vibrio contamination. Front Microbiol. 2016;7:350. doi:10.3389/fmicb.2016.00350 Ciriminna R, Meneguzzo F, Delisi R, Pagliaro M. Citric acid: emerging applications of key biotechnology industrial product. Chem Cent J. 2017;11:22. doi:10.1186/s13065-017-0251-y Sweis IE, Cressey BC. Potential role of the common food additive manufactured citric acid in eliciting significant inflammatory reactions contributing to serious disease states: a series of four case reports. Toxicol Rep. 2018;5:808-812. doi:10.1016/j.toxrep.2018.08.002 Additional Reading Citric acid and citrus allergy | AAAAI. The American Academy of Allergy, Asthma & Immunology. Genuis, Stephen. Sensitivity-related illness: The escalating pandemic of allergy, food intolerance and chemical sensitivity. Science of The Total Environment, Volume 408, Issue 24, 15 November 2010, Pages 6047-6061 By Jeanette Bradley Jeanette Bradley is a noted food allergy advocate and author of the cookbook, "Food Allergy Kitchen Wizardry: 125 Recipes for People with Allergies" See Our Editorial Process Meet Our Medical Expert Board Share Feedback Was this page helpful? Thanks for your feedback! What is your feedback? Other Helpful Report an Error Submit