2. Redness or Swelling

Allergies often cause redness and swelling, especially around the lips and face. Shellfish and eggs are among the common allergens that sometimes present with this symptom.

3. Allergic Rhinitis

While hay fever, or allergic rhinitis, is often caused by environmental allergens like mold or pollen, rhinitis is also a common symptom of dairy allergies. You should be more inclined to consider a food allergy as a possible cause of chronic congestion if symptoms never improve with a change in seasons or locations.

4. Eczema

Eczema, also known as atopic dermatitis, is an exceedingly itchy, painful, and scaly rash that usually appears near the face, elbows, and knees. It may be aggravated by sweat, clothing, or dryness, and it can be difficult to treat. Eczema is a common symptom of milk, egg, fish, and wheat allergies.

5. Gastrointestinal Distress

Diarrhea, nausea, and constipation are sometimes symptoms of a food allergy, especially to dairy products. However, they are perhaps more often signs of food intolerances; lactose intolerance and gluten intolerance are two fairly common intolerances that manifest with these symptoms.

6. Anaphylaxis

Anaphylaxis is the most serious — and, fortunately, the most uncommon and unmistakable — allergy symptom. Anaphylaxis, or anaphylactic shock, is a whole-body allergic reaction that causes difficulty breathing due to swelling in the airways and a rapid drop in blood pressure due to dilated blood vessels. Anaphylaxis usually develops quickly upon exposure to the allergen that triggers it, so the cause is often easily identifiable.Anaphylaxis is a medical emergency. If symptoms develop, call 911 immediately and administer any rescue medication you may have been prescribed as your physician has instructed.