| Clinical Condition | Onset | Mediation | Severity | System | Clinical Presentation/Symptoms |
| Anaphylaxis | Immediate | IgE-mediated | Severe★ | Multisystemic | A systemic response affecting several organs. Difficulty breathing, coughing, wheezing, severe distress, pallor, itchiness, hives, vomiting, floppiness and/or collapse15; can be fatal16 |
| Rhinitis, asthma, wheezing, and laryngeal edema | Minutes -1 hour [14] | IgE-mediated [14] | Mild-severe | Respiratory [14] | Various conditions that lead to respiratory distress [14] |
| Heiner syndrome | Days [17] | Non-IgE-mediated | Severe | Respiratory | Chronic/recurrent upper and lower respiratory tract infection, pulmonary hemorrhage [18]; typically misdiagnosed with pulmonary bronchopneumonia and pulmonary hemosiderosis |
| Acute urticaria and angioedema | Immediate (up to 60 min) [15] | IgE-mediated | Mild-moderate | Integumentary (skin) |
Urticaria (lesions characterized by polymorphic, round, irregular-shaped pruritic wheals), angioedema; non-pitting, non-pruritic, well-defined edematous swelling involving subcutaneous tissues such as face, genitals, buttocks, and hands [16] |
| Atopic dermatitis (atopic eczema) | Min/hours/days [15] | Mixed1 | Mild-moderate | Integumentary (skin) |
Impaired skin barrier function (urticarial lesions, itching, eczematous flares) due to a combination of genetic predisposition and exposure to allergenic triggers [16, 19, 20] |
| Allergic contact dermatitis | Min/hours/days1 | Mixed1 | Mild-moderate | Integumentary (skin) |
Eczema, pruritus, erythema, papules, vesicles, edema [16] |
| Immediate GI hypersensitivity (acute immediate nausea, pain, vomiting, and diarrhea) [13] | Immediate | IgE-mediated | Mild-severe | GI | Typically, a secondary manifestation of anaphylaxis[16] |
| Eosinophilic gastroenteritis (EoG) | Min/hours/days | Mixed | Severe | GI | Pathological infiltration of eosinophils into one or more segments of the GI tract[16] |
| Eosinophilic esophagitis (EoE) | Days[15] | Mixed | Severe | GI | Feeding disorder, vomiting, reflux, abdominal pain, abnormal histology in the esophagus (eosinophilic inflammation)[15], swallowing difficulty, poor weight gain[14] |
| Food protein-induced allergic-proctocolitis (FPIAP) | Hours/days [15] | Non-IgE-mediated | Mild-moderate | GI | Found in exclusively breastfed infants. Caused by food proteins from the maternal diet.[21] Visible specks of blood mixed with mucus in the stool; non-systemic (absence of vomiting, diarrhea, and growth failure)[16]; eosinophilic inflammation of the lower GI tract can be a common occurrence[1, 22] |
| Food protein-induced enterocolitis syndrome (FPIES) | 2-4 hours (typically) [15] | Non-IgE-mediated | Severe★ | GI | Profuse vomiting, +/− diarrhea, sudden onset of pallor and floppiness, 20% present as hypovolemic shock (with associated metabolic acidosis and methemoglobinemia), failure to thrive (FTT)[15, 16] |
| CMP-induced gastroesophageal reflux disease (GERD) | Hours/days[15] | Mixed [23] | Mild-moderate | GI | Constant regurgitation, poor feeding, refusal to eat[15] |
| CMP-induced enteropathy/food protein-induced enteropathy (FPE) | Hours/days | Non-IgE-mediated | Severe★ | GI | Vomiting, diarrhea, severe irritability, FTT, iron deficiency anemia, protein losing enteropathy[15] |
| Colic | Hours/days[15] | Non-IgE-mediated[24] | Mild-moderate | GI | Paroxysms of unexplained, inconsolable crying[15] |
| Constipation | Hours/days[15] | Non-IgE-mediated[24] | Mild-moderate | GI | Passage of infrequent and/or hard stools[15] |