Food Allergy vs. Food Sensitivity

Food Allergy vs. Food Sensitivity: Understanding the Difference

Many patients come to us with questions about adverse reactions to food. Some experience immediate symptoms like hives or swelling, while others report fatigue, digestive discomfort, or skin flare-ups hours or days later. These reactions are often attributed to either a food allergy or a food sensitivity, but the two are very different — and knowing which one you're dealing with is critical for both safety and effective treatment.

What Is a Food Allergy?

A food allergy involves the immune system. When someone with a food allergy eats a trigger food, their immune system identifies it as harmful and overreacts by releasing chemicals such as histamine. This can lead to immediate, sometimes severe, symptoms.

Common symptoms of a food allergy include:

• Hives or skin rash
• Swelling of the lips, face, tongue, or throat
• Wheezing or difficulty breathing
• Vomiting or diarrhea
• Dizziness or fainting
• Anaphylaxis — a life-threatening reaction that requires emergency treatment

These reactions typically occur within minutes to two hours of exposure.

Most common food allergens:

• Peanuts
• Tree nuts
• Milk
• Eggs
• Fish
• Shellfish
• Soy
• Wheat

Diagnosis and Management:

Food allergies are diagnosed using blood tests (IgE antibodies), skin prick testing, and sometimes oral food challenges under medical supervision. Management involves strict avoidance of the allergen and carrying an epinephrine auto-injector if there's a risk of anaphylaxis.

What Is a Food Sensitivity?

Unlike allergies, food sensitivities (or food intolerances) do not involve the immune system. Instead, they typically relate to how the digestive system processes certain foods.

Common symptoms of a food sensitivity include:

• Bloating or gas
• Stomach cramps
• Nausea
• Fatigue
• Headaches
• Skin issues (e.g., acne or eczema)
• Brain fog

These symptoms can be delayed and may not appear until several hours or even days after consuming the food, making them harder to identify.

Common food sensitivities:

• Lactose (in dairy)
• Gluten (non-celiac gluten sensitivity)
• Caffeine
• Food additives (e.g., MSG, artificial sweeteners)
• Certain preservatives

Diagnosis and Management:

Diagnosing a food sensitivity often involves an elimination diet, symptom journaling, and, in some cases, breath testing (e.g., for lactose intolerance). Management is typically focused on identifying and limiting trigger foods, and often, small amounts can be tolerated.

Why It’s Important to Know the Difference

Understanding whether you're dealing with an allergy or a sensitivity is more than a matter of comfort — it can be a matter of safety.

When to See a Doctor

If you suspect a food is affecting your health, it’s important not to self-diagnose or rely solely on at-home test kits. A thorough evaluation by a qualified medical provider can help identify the root cause and guide a safe and effective management plan.

How We Can Help:

Dr. Sima Stein of Sima Stein, MD, located in San Jose, California, is a board-certified physician who can help your child determine if he or she has a food allergy VS food sensitivity and how to help them manage it. Learn more about food allergy or sesitivity and the ways Dr. Stein can help you and your child manage their condition. Our team can assess underlying causes, recommend dietary changes, and provide safe, age-appropriate treatments—including allergy tests when necessary.

If you're concerned about your child’s bowel habits, we’re here to help. Call our office to schedule an evaluation. Sima Stein, MD, or request an appointment online today.