Food Sensitivity vs Food Allergy: What Is the Difference?
By Root Cause Test · Updated October 26, 2026
"Allergy," "sensitivity," and "intolerance" are often used as if they mean the same thing. They do not, and the difference matters for your safety and for choosing the right test.
Food allergy
A food allergy is an immune system reaction, often involving IgE antibodies. Symptoms usually appear within minutes to about two hours and can include hives, swelling of the lips or face, vomiting, wheezing, or anaphylaxis, which is a medical emergency. Even small amounts of the food can trigger a reaction.
How it is tested: by a licensed clinician using skin-prick tests, IgE blood tests, and sometimes a supervised oral food challenge. A wellness scan cannot test for, diagnose, or rule out an allergy.
Food intolerance
An intolerance is usually digestive rather than immune. Lactose intolerance is the classic example: the body lacks enough of the enzyme needed to digest lactose, which can cause bloating, gas, or diarrhea. Symptoms often depend on how much you eat.
How it is tested: some have specific clinical tests (for example, breath tests), and many are identified through elimination and reintroduction.
Food sensitivity
"Food sensitivity" is a broad, less precisely defined term. People use it for delayed, often milder reactions such as bloating, fatigue, headaches, skin changes, or brain fog that seem linked to certain foods, sometimes hours or a day later. Because the timing is delayed, it can be hard to tell which food is involved.
How people explore it: an elimination diet is the most practical method. Some people use an at-home wellness scan, such as a bioenergetic hair and saliva scan, as a starting list of foods to try removing first. Evidence for these scans is limited, so the list is a hypothesis to test, not a diagnosis.
Quick comparison
| Allergy | Intolerance | Sensitivity | |
|---|---|---|---|
| System involved | Immune | Usually digestive | Not precisely defined |
| Typical timing | Minutes to ~2 hours | Hours | Hours to a day or more |
| Can be dangerous? | Yes, can be life-threatening | Uncomfortable, rarely dangerous | Uncomfortable |
| Who tests it | A clinician | A clinician or elimination | Elimination diet; wellness tools as a starting point |
A simple elimination diet at home
- Pick 1 to 3 suspect foods (from your own notes or a wellness report).
- Remove them completely for 2 to 4 weeks. Read labels carefully.
- Track how you feel every day. Our free Food Scanner makes logging meals quick.
- Reintroduce one food at a time, waiting 2 to 3 days between each, and note any changes.
Do not run an elimination diet on foods that have caused allergic reactions, and talk to a clinician first if you are pregnant, have a history of disordered eating, or are planning changes for a child.
Curious what your own report would show?
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Related guides
- Bioenergetic Testing Explained: What It Is and What It Is Not
- Hair Sensitivity Test vs Lab Tests: An Honest Comparison
- How to Collect a Hair Sample at Home (Step by Step)
- How Much Does Bioenergetic Testing Cost? 2026 Price Comparison
- What is a bioenergetic hair and saliva scan?
Wellness information only. Not medical advice. Not an allergy test or medical diagnosis, and not intended to diagnose, treat, cure, or prevent any disease. Talk to a licensed clinician about symptoms or health conditions.