It is possible to be allergic to lemons but not oranges, even though both are citrus fruits. Food allergies can be highly specific, depending on the specific protein triggering the immune response. While citrus fruits share some common allergenic proteins, they also contain unique proteins or variations in protein structure that can lead to different reactions.
Understanding Citrus Allergies
A food allergy occurs when the body’s immune system mistakenly identifies a harmless food protein as a threat. In response, the immune system produces antibodies, triggering the release of chemicals like histamine, leading to allergic symptoms.
Citrus allergies are considered rare compared to other common food allergies, but they can affect individuals of any age. Symptoms can range from mild to severe, appearing shortly after contact with or consumption of the fruit. This immune system reaction to specific proteins defines a true food allergy, distinguishing it from food sensitivities or intolerances that do not involve an immune response.
Why Reactions Can Differ Between Citrus Fruits
Citrus fruits, including lemons and oranges, contain various proteins. Some are common across the family, while others are unique or present in different concentrations. Major allergens identified in citrus fruits include profilins and lipid transfer proteins (LTPs).
A person’s immune system might react to a protein found in lemons that is either absent in oranges or structurally different enough not to trigger a reaction. Profilins are proteins found in many plants, including citrus fruits, often associated with oral allergy syndrome (OAS) in individuals with pollen allergies. Their specific structure and concentration can vary between lemon and orange, influencing whether a reaction occurs.
Lipid Transfer Proteins (LTPs) are another family of allergens known for cross-reactivity among various fruits. Subtle differences in these proteins or the presence of other unique allergenic proteins can explain why a person might react to lemons but not oranges.
Recognizing Symptoms and Seeking Diagnosis
Symptoms of a citrus allergy can manifest in several ways, from localized to more severe responses. Mild symptoms often include oral allergy syndrome (OAS), characterized by tingling, itching, or swelling of the lips, tongue, and throat. Skin reactions, such as redness, hives, or contact dermatitis, may occur upon touching citrus peels.
More severe reactions can include gastrointestinal issues like nausea, vomiting, and stomach pain, or respiratory symptoms such as wheezing, coughing, and difficulty breathing. The most serious reaction is anaphylaxis, which can involve widespread hives, swelling of the mouth and throat, a sharp drop in blood pressure, and loss of consciousness. Seek immediate medical attention if anaphylaxis is suspected.
Diagnosing a citrus allergy typically involves a healthcare professional, such as an allergist. The process may include a detailed medical history and physical examination. An allergist might perform a skin prick test, where a small amount of allergen extract is pricked onto the skin, with a positive reaction indicated by a raised bump or redness. Blood tests, which measure IgE antibodies to specific food proteins, can also be used. In some cases, an oral food challenge, conducted under medical supervision, may be performed to confirm a diagnosis by carefully introducing the suspected food.
Living With a Citrus Allergy
For individuals diagnosed with a citrus allergy, the primary management strategy involves avoiding the specific citrus fruit that triggers a reaction. This requires careful attention to food labels, as citrus ingredients can be present in many processed foods, beverages, sauces, and some personal care products. Common hidden sources can include juices, flavored yogurts, marinades, and certain vitamin supplements.
For those at risk of severe allergic reactions, an allergist will prescribe an epinephrine auto-injector, such as an EpiPen. This device delivers a dose of epinephrine, the first-line treatment for anaphylaxis, and should be carried at all times. Learning how to properly use the auto-injector and educating close contacts is important. Ongoing consultation with an allergist is important to develop a personalized management plan, discuss emergency protocols, and review any new symptoms or concerns.