A food allergy is an immune reaction to a food protein, most often peanut, tree nuts, milk, egg, shellfish, fish, wheat, soy or sesame. Reactions usually start within minutes to two hours and can range from hives to life-threatening anaphylaxis.
Key symptoms
- Hives, itching or flushing after eating
- Swelling of the lips, tongue or face
- Vomiting, belly cramps or diarrhea
- Wheezing, throat tightness or hoarse voice
- Dizziness or fainting from low blood pressure
What you find on exam
- Airway, breathing and circulation first
- Skin for hives and swelling
- Wheezing or stridor on lung exam
- Blood pressure and heart rate for signs of shock
Tests
- Diagnosis is mainly from a clear history linking a food to symptoms
- Skin prick tests or food-specific IgE blood tests
- Oral food challenge by an allergist to confirm or rule out allergy
- Serum tryptase soon after a severe reaction
Treatment basics
- Anaphylaxis: intramuscular epinephrine in the outer thigh right away
- Then oxygen, IV fluids, and antihistamines such as cetirizine as add-ons
- Strict avoidance of the food and reading labels
- Prescribe two epinephrine auto-injectors with a written action plan
Red flags
- Trouble breathing, throat tightness or stridor
- Low blood pressure, fainting or confusion
- Symptoms returning hours later (biphasic reaction)
Practice it in Making Synapses
Making Synapses cases
Related guides
Sources: NCCPA PANCE Content Blueprint; NBOME COMLEX-USA clinical presentations; AAMC Core Entrustable Professional Activities (Core EPAs). Written by Making Synapses. Making Synapses is not affiliated with these organizations.