From the Guidelines
Yes, you can have a reaction to food from Oral Allergy Syndrome (OAS) even if there's no skin reaction. OAS typically causes immediate allergic symptoms in the mouth and throat when eating certain raw fruits, vegetables, or nuts due to cross-reactivity with pollen allergies, as noted in guidelines for diagnosing and managing food allergies 1. Common symptoms include itching or tingling of the lips, mouth, and throat; swelling of the lips, tongue, or throat; and sometimes nausea or abdominal pain—all without any visible skin reaction.
Key Considerations
- The diagnosis of food allergy, including OAS, often involves oral food challenges, with the double-blind, placebo-controlled food challenge (DBPCFC) being the gold standard 1.
- A positive diagnosis can be supported by a single-blind or open-food challenge if it elicits objective symptoms that correlate with medical history and are supported by laboratory tests 1.
- Management of OAS symptoms can include avoiding trigger foods, cooking the foods (which often breaks down the allergenic proteins), peeling fruits (as allergens are concentrated in the skin), or taking antihistamines like cetirizine (10mg daily) or diphenhydramine (25-50mg as needed) before consuming trigger foods.
Important Details
- Some individuals may need to carry epinephrine auto-injectors (like EpiPen) if they've had severe reactions.
- OAS occurs because proteins in certain foods are structurally similar to pollen proteins, so your immune system mistakes them for the pollen you're allergic to, triggering symptoms primarily where the food contacts mucous membranes rather than affecting the skin.
- It's crucial to conduct oral food challenges under medical supervision due to the risk of severe allergic reactions, as emphasized in the guidelines 1.
From the Research
Oral Allergy Syndrome (OAS) Reactions Without Skin Reactions
- OAS is a type of food allergy that occurs when the body's immune system reacts to certain foods, typically fresh fruits, vegetables, and nuts, due to cross-reactivity with pollen allergens 2, 3.
- The symptoms of OAS can include itching and swelling of the lips, palate, and tongue, and can occur immediately after consuming the offending food 2, 3.
- While skin tests are often used to diagnose OAS, it is possible for patients to experience reactions without a skin reaction 4, 5.
- In some cases, patients with OAS may experience more severe systemic or anaphylactic reactions, even if they do not have a skin reaction 4.
- The diagnosis of OAS is primarily based on the patient's history and confirmed by oral provocation tests, and a multidisciplinary approach is necessary for diagnosis and treatment 2, 3.
Risk of Anaphylaxis in OAS Patients Without Skin Reactions
- Patients with OAS are at risk of anaphylaxis, even if they do not have a skin reaction, and this risk may be increased by factors such as changes in pollen and pollution levels, and sensitization to other plant food allergens 4.
- It is essential for clinicians to be aware of the possibility of OAS and to take a thorough history to diagnose and manage the condition effectively 3, 6.
- Further research is needed to determine the risk factors for severe reactions and sensitization patterns to pollens and plant food allergens in patients with OAS 4, 6.