# Pollen-Food Allergy Syndrome: Allergens, Clinical Insights, Diagnostic and Therapeutic Challenges
## 5 PFAS Symptoms and Effect on Quality of Life  
PFAS symptoms typically appear within minutes of consuming fresh fruits, vegetables, nuts, legumes, or seeds and range from mild, localized reactions to rare but potentially severe systemic manifestations [44]. The clinical presentation depends on various factors, including the specific allergen involved, individual sensitivity, and the presence of exacerbating cofactors, as previously mentioned. The hallmark of PFAS is its localized manifestation in the oropharyngeal region (OAS). Most patients experience pruritus and paresthesia in the mouth, lips, tongue, and throat shortly after ingesting raw fruits, vegetables, nuts, seeds, or legumes. These symptoms are often accompanied by mild swelling (angioedema) of the oral mucosa, lips, or tongue [31]. In some cases, erythema or vesicle formation on the mucosa may occur, further contributing to discomfort [58]. Laryngospasm and dysphonia are less common but can occur when swelling affects the laryngeal structures [33]. Despite their discomfort, these localized symptoms are usually transient, resolving within a few minutes to half an hour without medical intervention. While PFAS predominantly affects the orophnx, it can occasionally extend to other systems. Gastrointestinal symptoms, including nausea, abdominal pain, vomiting, and diarrhea, have been reported in some cases [94]. These symptoms are more likely when larger quantities of the triggering food are consumed or when cofactors such as exercise or alcohol are present, which can amplify the allergic response [95]. Respiratory symptoms, though rare, may include nasal congestion, sneezing, or mild wheezing. These manifestations suggest a broader systemic immune activation rather than localized reactivity [96]. Although uncommon, systemic manifestations of PFAS can occur, with symptoms ranging from urtica (hives) and widespread angioedema to potentially life-threatening anaphylaxis [97]. Systemic reactions are estimated to occur in approximately 2-10% of PFAS cases, with severe outcomes such as hypotension and respiratory distress being extremely rare (1-2%) [54; 57; 62; 63]. These more serious presentations are often linked to heat-stable allergens, such as those found in nuts, LTPs, and GRPs, or when cofactors like NSAIDs or physical activity lower the reaction threshold [54; 94; 96]. Anaphylaxis represents the most critical concern in PFAS and underscores the need for vigilance in susceptible individuals [63]. For patients who experience severe systemic reactions to specific foods, strict avoidance of those foods in any form is strongly advised [98; 99]. The clinical spectrum of PFAS is influenced by the stability of the allergenic proteins involved. Allergens from the PR-10 and profilin families are heat- and digestion-labile, often leading to mild, localized reactions that resolve with cooking or processing of the food. In contrast, heat-stable proteins, such as those found in nuts, peanuts, and LTPs, are more likely to cause severe or systemic reactions, even after the food has been cooked [33]. The type of food consumed and the patient's underlying pollen sensitization profile also play a significant role [54; 63; 100]. For example, individuals sensitized to birch pollen are more likely to react to apples and carrots, while those with ragweed sensitization may react to melons or bananas. Although PFAS symptoms are generally mild and self-limiting, they can significantly impact the quality of life for affected individuals. Fear of reactions may lead to the avoidance of specific foods, potentially resulting in nutritional deficiencies or a restricted diet [58]. Moreover, the unpredictability of symptoms, particularly in the presence of cofactors, can contribute to anxiety and a reduced sense of well-being [101]. Patients with PFAS often find it difficult to anticipate the severity of their reactions, as seemingly benign foods may trigger mild symptoms in one instance and more severe reactions in another.