Is It a Food Allergy or Just Food Intolerance? Reading the Reaction Types, the Five Emergency Signs and the Sample Symptom Diary

In a food allergy, the immune system mistakes a food protein for a threat and releases chemicals such as histamine. This can affect the skin, airways, gut and circulation within minutes. In a food intolerance, the body has trouble digesting or reacting to a food, for example because it lacks an enzyme.

The National Institute of Allergy and Infectious Diseases provides an overview of food allergy, and MedlinePlus has a plain-language page on food allergy.

In the United States, nine foods are responsible for most serious allergic reactions and must be declared on packaged food labels.

If your symptoms are mostly digestive and long-lasting, read our guide on irritable bowel syndrome and talk with a clinician before cutting out whole food groups.

Anaphylaxis is a severe, whole-body allergic reaction that can progress quickly. Call 911 if you see these signs after eating, being stung or taking a medicine:

1. Trouble breathing: wheezing, noisy breathing, a tight throat or a hoarse voice.
2. Swelling of the lips, tongue, face or throat.
3. Widespread hives, itching or flushing along with other symptoms.
4. Repeated vomiting, severe stomach cramps or diarrhea after a suspected allergen.
5. Dizziness, a weak or fast pulse, pale or clammy skin, or fainting.

If a person has been prescribed epinephrine, it is the first-line treatment and should be used as directed without waiting, followed by an immediate call to 911. Even if symptoms improve, emergency evaluation is needed because reactions can return.

Make an appointment, or visit sooner if symptoms are severe, when:

1. You have had hives, swelling, vomiting or wheezing soon after eating a particular food.
2. A child has a reaction to a new food, especially egg, milk or peanut.
3. You regularly get bloating, diarrhea or stomach pain after meals and do not know why.
4. You have been avoiding foods on your own and are worried about nutrition.
5. You carry or have been prescribed an epinephrine auto-injector and need a plan.

For children, see our guide on telling a common childhood illness from one that needs a doctor. If you already have asthma, allergies can make it harder to control, so read how to keep asthma under control.

Never test a suspected severe food allergy at home by eating the food again. A positive blood or skin test also does not always mean you will react, which is why results need expert interpretation. Your clinician may refer you to an allergist, as explained in our guide on when your primary care doctor sends you to a specialist.

For possible intolerance or unclear digestive symptoms, a simple food and symptom diary can show patterns. This is a teaching example. Bring your own diary to a visit. The squares show example symptom levels.

In this made-up diary, symptoms followed dairy-containing meals, a pattern a clinician could explore with lactose testing or a supervised trial. A diary is not a diagnosis. Any breathing trouble, swelling or hives is never a diary situation; it needs urgent care.

If you or your child has a confirmed food allergy:

1. Read every label and learn the ingredient names for your allergen.
2. Ask about ingredients and cross-contact at restaurants, and tell the staff clearly.
3. Keep epinephrine auto-injectors with you, check expiry dates and learn to use them.
4. Create a written emergency action plan and share it with family, school and workplace.
5. Wear medical identification if your clinician advises it and review the plan every year.

If you have reacted to a food or have ongoing stomach symptoms after eating, our team can review your history and guide testing and referrals. For non-emergency questions, Contact Us, book a visit, or find City Prime Care on Google: City Prime Care on Google.

A food allergy and a food intolerance can feel alike at first, but they carry very different risks. Know the emergency signs, keep a diary for unclear symptoms and get testing and advice from a clinician before removing foods. This article is for general education and does not replace medical advice.