How should I evaluate and manage a female patient who develops vomiting and widespread allergic symptoms after eating tomatoes?

Evaluation and Management of Tomato-Induced Allergic Reaction with Vomiting and Widespread Symptoms

This patient is experiencing IgE-mediated food allergy to tomato, potentially progressing to anaphylaxis, and requires immediate assessment for life-threatening symptoms followed by confirmatory diagnostic testing and strict avoidance counseling. 1

Immediate Assessment for Anaphylaxis

Determine if this meets anaphylaxis criteria immediately, as tomato can cause severe IgE-mediated reactions including laryngeal edema and anaphylaxis in adults. 2 Anaphylaxis is highly likely if any one of these criteria is present: 1

• Acute onset (minutes to hours) with skin/mucosal involvement (hives, flushing, swollen lips/tongue) PLUS respiratory compromise (dyspnea, wheeze, stridor) OR hypotension OR persistent GI symptoms (vomiting, cramping abdominal pain) 1
• Two or more organ systems involved rapidly after tomato exposure: skin symptoms, respiratory symptoms, reduced blood pressure, or persistent vomiting 1

Critical Red Flags Requiring Immediate Epinephrine

• Respiratory symptoms: throat tightness, difficulty swallowing, stridor, wheeze, or dyspnea indicate laryngeal edema or bronchospasm 1, 2
• Cardiovascular symptoms: dizziness, hypotension, tachycardia, or syncope 1
• Coexisting asthma dramatically increases risk of fatal anaphylaxis and is the most important risk factor for death from food-induced anaphylaxis 1

If anaphylaxis is present, administer intramuscular epinephrine immediately before any other intervention, as delayed epinephrine is associated with fatalities. 1 Deaths from food-induced anaphylaxis occur within 30 minutes to 2 hours of exposure. 1

Diagnostic Approach

Step 1: Detailed Clinical History

Focus on these specific elements to establish IgE-mediated food allergy: 1

• Timing: Symptoms occurring within minutes to 2 hours after tomato ingestion strongly suggest IgE-mediated allergy 1, 3
• Reproducibility: Has vomiting and widespread allergic symptoms occurred on more than one occasion after eating tomato? 1
• Symptom pattern: Document which body systems are involved—skin (urticaria, angioedema, flushing), GI (vomiting, cramping), respiratory (throat tightness, wheeze), or cardiovascular (dizziness, hypotension) 1, 3
• Quantity and form: Did symptoms occur with raw tomato, cooked tomato, or tomato products? 2
• Personal history of atopy: Presence of atopic dermatitis, asthma, or other food allergies increases likelihood 1
• Family history of atopy is a risk factor for food allergy development 1

Common pitfall: Do not assume this is viral gastroenteritis or food poisoning—the temporal relationship to a specific food (tomato) occurring on multiple occasions distinguishes IgE-mediated food allergy from other causes. 1, 4

Step 2: Confirm Sensitization with Testing

Perform skin prick testing (SPT) to tomato as the first-line diagnostic test to identify IgE-mediated sensitization. 1 SPT is preferred over serum-specific IgE because it provides immediate results and has similar diagnostic accuracy. 1

• SPT alone cannot diagnose food allergy—it only confirms sensitization, which must be correlated with clinical history 1
• Serum tomato-specific IgE testing (ImmunoCAP) is an alternative if SPT is unavailable or contraindicated 1
• Do NOT perform intradermal testing—it is not recommended for food allergy diagnosis due to poor specificity and increased risk of systemic reactions 1
• Do NOT measure total serum IgE—it has no diagnostic value for food allergy 1

Step 3: Elimination Diet for Diagnostic Confirmation

Implement strict tomato elimination for 2-4 weeks and monitor for symptom resolution. 1 This supports the diagnosis if symptoms completely resolve during avoidance. 1

Step 4: Oral Food Challenge (If Diagnosis Uncertain)

Double-blind placebo-controlled food challenge (DBPCFC) is the gold standard for definitive diagnosis, but is only necessary if history and testing results are discordant or equivocal. 1

Do NOT perform oral food challenge if: 1

• History clearly indicates anaphylaxis to tomato
• Recent severe reaction occurred
• Patient has poorly controlled asthma

Oral food challenges must be performed in a medically supervised setting with immediate access to epinephrine and resuscitation equipment. 1

Management Strategy

Acute Treatment (If Currently Symptomatic)

For anaphylaxis or severe symptoms: 1

• Epinephrine 0.3-0.5 mg intramuscular (anterolateral thigh) is first-line treatment 1
• Position patient supine with legs elevated (unless vomiting or respiratory distress) 1
• Administer supplemental oxygen if available 1
• Establish IV access and give normal saline bolus if hypotensive 1
• Antihistamines and corticosteroids are adjunctive only—never delay or substitute for epinephrine 1
• Monitor for biphasic reactions (recurrence 1-72 hours later, typically around 8 hours) requiring observation period of at least 4-6 hours 1

For isolated vomiting without anaphylaxis: 5

• Oral rehydration therapy is primary treatment 5
• Ondansetron 4-8 mg may be considered if persistent vomiting prevents oral rehydration 5

Long-Term Management

Strict avoidance of tomato and tomato-containing products is the cornerstone of management. 3, 6 Provide detailed education on: 1, 6

• Reading food labels carefully for tomato ingredients (tomato paste, sauce, puree, concentrate, sun-dried tomatoes) 6
• Cross-contamination risks in restaurants and food preparation 7
• Hidden sources: soups, sauces, pizza, pasta dishes, ketchup, salsa 6

Prescribe epinephrine auto-injector (two devices) for emergency use and provide training on proper administration technique. 1 Patients with confirmed IgE-mediated food allergy causing systemic symptoms require epinephrine auto-injectors. 1

Develop written emergency action plan detailing: 1

• Recognition of allergic reaction symptoms
• When and how to administer epinephrine
• When to call emergency services
• Follow-up care instructions

Special Considerations

If patient has asthma: 1

• Optimize asthma control aggressively—poorly controlled asthma is the strongest risk factor for fatal food-induced anaphylaxis 1
• Consider more frequent follow-up and lower threshold for epinephrine administration 1

Medication review: 1

• Beta-blockers may decrease response to epinephrine and increase severity of anaphylaxis 1
• ACE inhibitors and angiotensin receptor blockers may prolong or worsen symptoms 1
• Consider alternative medications if possible 1

Common Pitfalls to Avoid

• Do not rely on antihistamines alone for treatment—epinephrine is the only effective treatment for anaphylaxis and must not be delayed 1
• Do not assume mild past reactions predict future severity—the severity of allergic reactions is unpredictable and cannot be determined by prior reaction history or testing levels 1
• Do not perform food challenges at home—they must occur in supervised medical settings with emergency equipment available 1
• Do not confuse with oral allergy syndrome—while tomato can cause OAS (mild mouth itching), this patient's systemic symptoms with vomiting indicate true IgE-mediated food allergy requiring different management 1, 3
• 50-90% of self-reported food allergies are not confirmed upon testing—objective confirmation with SPT/specific IgE plus clinical correlation is essential 1

Follow-Up

Refer to allergist/immunologist for comprehensive evaluation, confirmatory testing, and ongoing management. 1 Allergist follow-up allows for consideration of component-resolved diagnostics if needed and monitoring for potential tolerance development over time. 1