Are your symptoms a food allergy vs food intolerance?

Why is it important to know if you have a food allergy vs food intolerance?

Many people have problems with food, and many doctors seem to just tell you to “avoid it.”   But don’t you deserve better than that?  Especially since one is caused by a potentially life threatening immune response and the other potentially causes you to feel absolutely miserable.  If nobody has clarified this for you, then read this article because I will help you figure out whether your symptoms are caused by a food allergy vs intolerance.

Picture of food allergy vs food intolerance.
Is it a food allergy vs food intolerance?

Is it a food allergy vs food intolerance?

This week, 40% of my patients have had at least one food concern and their question is always the same:  am I having a food allergy vs food intolerance?  Of this week’s patients, there are three who I thought would be a good example for this post:

Beth is a woman who saw me because she has been having increasing abdominal pain with multiple foods.  She had been unable to find the cause and has recently become gluten and dairy-free as an attempt to solve this pain on her own.  When that didn’t help, she came to see me to try and find out whether she had a food allergy vs food intolerance.

Yousef is a 4 year old I saw who recently stopped eating foods.  He said that yogurt caused a stomach ache and when he ate peanut butter it “caused his mouth to hurt.”  He had never had any swelling of the tongue and no rash, but now was avoiding any new food and was only eating cereal (with milk), spaghetti and fruit.  Yousef’s mom wanted to know if this was a food allergy vs intolerance or if he was just being picky about new foods.

Finally, Michael came to see me just 2 days ago.  He has a history of a shellfish allergy since he was a child and told me that when he ate it he would “swell up like a balloon” and get hives.  He had always been able to eat fish without a problem but recently had “a small rash” across his face and chest after eating fish.  He was worried that he had developed a new fish allergy.


As you can guess, multiple times a day I see people who want to know if they have a food allergy vs food intolerance.  It is the RIGHT question to ask and each of them were correct in wanting to find out the answer.


The common “treatment” for food allergy vs food intolerance

Unfortunately, many people (and sadly, many doctors) tend to associate ANY food reaction with an allergy and give the advice “just avoid it.”

There are no jokes when it comes to food allergy vs intolerance
Food allergies vs intolerance is NO JOKE!

That advice is as bad as the classic “it hurts when I do this” doctor joke.

But your symptoms are no joke and it’s time to stop treating them like one.

Trying to determine if a reaction is a food allergy vs intolerance is an important one regardless of the trigger because the treatment for food allergy is very different than that of food intolerance.  And it is important to get the right treatment for YOU and not just some generalized advice.


I have written this article (which, as a warning, is long) because I want to help everyone determine their symptoms are truly a food allergy vs food intolerance.


NOTE:  If you don’t have time to read this article now, you can download it here and save it for later.


What are different causes of food allergy vs food intolerance?

First, we need to talk about the cause of each type of reaction.  This is important because it’s how I, as an allergist, know how to interpret your symptoms, know what tests to order for you and, ultimately, know how to create your long term plan.

This step is also the step skipped by most medical providers.

The result:  bad treatment plans.  But we can fix that today by discussing the causes of food allergy vs intolerance:


Food Allergy: An allergy is an IgE antibody mediated immune system response to a specific trigger (in this case, a food).

  • The main problem is that your  body thinks the food is attacking it
  • As a result, you body reacts as if the food were bacteria or viral infection
  • This leads to true inflammation and activates a full immune response

Food Intolerance: As a general rule, if a food causes a symptom that is not a food allergy, it is a food intolerance.  This means the majority of reactions are actually food intolerance. It also means there are many different causes of food intolerance:

  • Foods can directly irritate your skin or body
  • Foods can be processed into something that irritates your skin or body
  • Foods can cause a chemical response that is undesired
  • Foods can cause a normal response that is undesired
  • Foods can cause a type of inflammation that activates the basic immune system (innate system)
    • This can cause mild inflammation, typically not as severe as an allergy
    • This does not activate the full immune system.


What are the symptoms of food allergy vs intolerance?

The MOST IMPORTANT thing I can do when I am trying to figure out if you have a food allergy vs food intolerance is to LISTEN TO YOU.  By listening to you describe your symptoms, usually the answer can be figured out.

Did you know that a medical provider will interrupt you within 12-18 SECONDS?

Worse, 23% of patients aren’t able to say their full concerns BECAUSE of doctors interruption!


With food allergy, you NEED to be heard.  It is the most important step in your diagnosis!

If nobody else is listening, please ASK ME!  I will listen and help you figure out food allergy vs intolerance the RIGHT way!


As a general rule a doctor should have about 80-90% certainty of your diagnosis after just talking (and more specifically, listening) to you.   As a result, I spend more time listening to symptoms than anything else.

So what are the typical food allergy vs food intolerance symptoms?

Food Allergy:  Allergy symptoms tend to be relatively predictable.  Typical food allergy symptoms might include:

    • Hives / welts – these skin reactions happen in about 90% of patients with an allergy.

Pro-tip: if you have a rash, take pictures!

Cell phones and the ability to take pictures has made it so much more accurate to distinguish between allergy vs intolerance.

    • Hives tend to be itchy welts with individual lesions lasting < 24 hours
    • Although the total rash itself might come and go over more than a day
  • Swelling – there may also be swelling (angioedema) of the mouth, face, hands, feet, or groin area.
  • You can get abdominal pain, nausea, vomiting or loose stools.
  • You might get lightheaded, feel dizzy or about to pass out
  • Allergic reactions also carry with them the risk of death! (anaphylaxis)

Food Intolerance:  Since a food intolerance is caused by many different factors, the symptoms are less predictable.  One of the keys to diagnosing food intolerance is to make sure it’s NOT an allergy.  So read through the allergy symptoms again.  If none of it sounds like you, then you more likely have a food intolerance.

Typical symptoms might include one or many of the following:

  • Rash – not a hive rash, but a red rash that may/may not be itchy and tends to last for > 24 hours
  • There is rarely swelling
  • There is often abdominal pain, nausea, possibly vomiting, constipation or loose stools. This is a very common symptom with food intolerance.
  • Headaches sometimes happen. But feeling lightheaded, dizzy or passing out is very unusual for a food intolerance.
  • May feel fatigued or decreased energy
  • Weight gain or weight loss is not a usual symptom of intolerance although it can happen. It is always important to search for more common causes of weight changes is this is the only problem.
  • An intolerance should not kill you. It might make you feel miserable… and I’ve heard a few symptoms that sound worse than death (figuratively), but the risk of death is an allergy.



If you want to figure out whether you have a food allergy vs intolerance RIGHT NOW, download and fill out this quiz!  Then continue reading to learn about testing and the long term treatment plan.

Click Here for your Free Quiz:
“Do my symptoms suggest food allergy or food intolerance?

What tests are used to diagnose a food allergy vs intolerance?

In my daily practice, by just listening I get a pretty good idea whether you have a food allergy vs food intolerance BEFORE I order any test.  This is what all medical providers should do for you as well.   In addition, your provider should have a plan for both if the labs are positive and if the labs are negative.

Unfortunately, it is far too common that a medical provider does testing and then confidently tells you “what it isn’t” but doesn’t have a plan to determine “what it is.”

I HATE this!

It’s bad doctoring… and very annoying.

As a general rule, testing should CONFIRM the doctor’s suspicion of food allergy vs food intolerance.  The lab test BY ITSELF does not determine whether you have a food allergy or intolerance.

Food Allergy:  Allergy testing can be performed with either a skin test or a blood test.

  • A skin test should cause a hive to the food in question.
  • A blood test should have a positive IgE reading
  • If one of these tests is negative/normal and the suspicion is high for allergy, the other should be done.
  • There is always the option for an allergist to have you eat the food/use the product and “see what happens.”
    • This is not a preferred option and usually an ingestion challenge is reserved for when you’ve outgrown an allergy or when we are finding a safe alternative.
    • It is not standard practice to do an ingestion challenge to cause a reaction.

Food Intolerance:  There is no standardized testing for intolerance.  For some specific types of intolerance, there are some tests (lactose tolerance test, celiac test) but a “general test” does not exist.

  • Most of the time the first step is to rule out an allergy, so we often do an allergy test expecting it to be normal.
  • For many people with food intolerance, the test is simple:
    • Remove the trigger and the symptoms should go away
    • Return the trigger and the symptoms should return
    • Remove them again and the symptoms should go away, and then keep avoiding
      • Ideally, this would be done as a “blinded” test where you don’t know if you are exposed to the trigger or not.
      • This eliminates confirmation bias.
      • Of course, this needs to be done with your knowledge. Someone just doing this test secretly to you is not a nice person.


The reason to care about food allergy vs food intolerance

The reason I take a good, long history and then confirm with testing is for one reason:  to create your long term treatment plan.

The long term treatment plan is VERY DIFFERENT in food allergy vs intolerance:

Food Allergy:  Remember when you were a kid and got vaccines so that your immune system would protect you against polio, pertussis, diphtheria, etc?  Well, a food allergy is also an immune response… and your body thinks it is now “protecting” you against the food.  *Yay immune system* (read in a sarcastic voice).  The problem is that food allergy is often a life long problem.

As a result, the long term plan for food allergy is:

  • Avoid the product (likely for life, since your body will always protect you from that food)
  • Accidental exposure could result in death
  • You will likely need an injectable epinephrine pen, school forms for strict avoidance, and an anaphylaxis action plan.

Food Intolerance:  Intolerance is different.  An intolerance might be lifelong (lactose or celiac disease) or it might be temporary.  If it’s temporary, there is no good way to tell when it is ok to bring back the food.  You just have to try and see.  For this reason, the general plan for intolerance is:

  • Avoid the food (for now)
  • Wait an amount of time. Possibly 3 months, 6 months, a year (discuss this with a medical provider).
  • At some point, consider bringing back the product.
    • If you can tolerate it again — Great! No more problem.
    • If not then remove it again for another 3, 6, 12 months.
  • Accidental ingestion will likely trigger your symptoms but will not cause a risk of death.
  • There is no need for an epipen or school forms


I know this was a long post.

But as you can see, distinguishing food allergy vs food intolerance is very important because they ultimately have  VERY different treatment plans.

And when it comes to figuring out your health, there should be no shortcuts in deciding whether you have a food allergy vs intolerance.


Since it was so long, I have also included the entire post here here so you can download it and read it later.

And if you have any questions, or think you might not be getting the care you deserve, please let me know and I might be able to help!


Next Steps:

  • If you have a story similar to those above, share them in the comments below.  I think the more stories (both good and bad) that are shared, the more it can help people struggling with this problem.
  • As always, if you KNOW someone who is having a difficult time with food allergies vs food intolerance, PLEASE SHARE this page with them on Facebook, Twitter, Google+ or pin this article on Pinterest.  Be a good friend or family member and help them get the right answer.
  • Finally, if this article helped you figure out your own symptoms, share what you had below!  I’ll track the results and post them as a follow up in the future.






Beckman HB, Frankel RM. The effect of physician behavior on the collection of data.  Ann Intern Med. 1984 Nov;101(5):692-6.

Rhoades DR1, McFarland KF, Finch WH, Johnson AO.  Speaking and interruptions during primary care office visits.  Fam Med. 2001 Jul-Aug;33(7):528-32.

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  1. I am 7 months pregnant and seem to have developed an intolerance to eggs for the first time in my life. After eating eggs I experience vomiting, painful bloating, flatulence and diarrhea.

    Is it unusual to develop an intolerance during pregnancy? Will it go away after baby is born? Is it possible baby will have the same intolerance or an allergy?

    • Lonnie,

      Great question. Pregnancy throws a lot of allergy symptoms off… to the point that the ‘official’ advice is that 1/3rd of people will have allergies get better, 1/3rd will be the same, and 1/3rd will get worse (so… all bets are off).

      Given your symptoms, I think that your symptoms ARE more likely an intolerance (as you mentioned) and not a true allergy. This is good news… because the hope is that if you avoid it for a little while your GI system might ‘reset’ and you’ll be able to eat eggs again.

      So probably best to avoid them for now and then try to reintroduce them after your baby is born. There is a good chance you’ll be able to eat eggs again at that time.

      PS – also, it is very unlikely, given your history, that your baby will have a significant intolerance or allergy to eggs. Of course, I can’t know for sure… but the odds are in your favor!

  2. So I’ve got a complicated medical history, Crohn’s, arthritis, fibromyalgia, colostomy bag and nine surgeries.
    Just this week I was rushed to hospital bleeding profusely from my Stoma site, and they had to give me three bags of blood (I was lucky to even be alive. I lost a lot of blood and I was freezing but wanted a cold fan on me. Sweating so badly that my hair looked like it had been just washed and they couldn’t find a vein. So got a central line into my heart through my neck.) anyway. After moving from ICU to HDU I was allowed to eat an egg sandwich and mushroom soup. After I’d finished both my lip started to swell majorly. My heart rate shot upnto 134 and blood pressure dropped, majority of my was so itchy and painful. I had red raised lumps all over my body that were so itchy. I was taking antihistamines and they did absolutely nothing. It was only when they put a steroid into me that my body calmed down.

    I’ve never had issues with eggs. Ever. I grew up in a farm yard and raised chickens and ate eggs every day because they were free. Only now at 26 had it presented itself after a blood and plasma transfusion.

    My doctors think I’m eating eggs on purpose to become sicker and I can tell they don’t believe an egg intolerance can present itself at 26 years old. Now I’m freaking out incase I have had it all this time and didn’t notice. But I’ve never had any reaction to eggs before.

    I’m really scared.

    • I’m very sorry that all this has been going on for you. There are two ideas that come to mind:

      – First, it IS possible to develop a food allergy at any time. Period. And given your symptoms I would certainly be worried about a true food allergy/anaphylaxis. It can be checked with an IgE test, either skin test from an allergist or a blood test from your primary care.

      – Second, it is possible that you acquired the egg allergy from blood transfusions. There are reports of people getting food allergy from blood products (there are a lot of articles online but this is a decent scientific article showing its possible).

      In many ways, it doesn’t matter how you got it because at this point the right medical path is to do allergy testing to determine if it is a true allergy vs a severe intolerance, and then have you avoid eggs. It is frustrating to read (and I can tell extremely frustrating for you to experience) how they are not checking it. I would try to keep pushing forward for appropriate testing and avoid eggs in all forms currently (that’s at least something YOU can control).

      If you have more questions, feel free to email me and I’ll be happy to give you all the help i can.

  3. Hi Dr. Webber! I just wanted to say how great what you’re doing is. Through my late teens and early 20’s I struggled constantly with a plethora of debilitating symptoms that I could not get answers to. I learned to cope, sort of, but was truly miserable and in hindsight I can see that I was heading towards a premature grave. It was very serious. When I started regularly passing respectable amounts of blood is when I finally thought, “Okay, this is getting scary. Something has to change.” I wish that I had had such a resource as this website, even this one article, back then. All I could find was conflicting information.

    I realized that certain foods always caused certain symptoms, namely severe gastrointestinal pain, vomiting, and other fun things. So by trial and error I cut out foods such as soy (not easy when you’re living in a vegan boarding school!), gluten, and dairy. A few years later I saw a naturopath endocrinologist that really helped me set my feet on the path of diagnosis, and discovering and treating both Addison’s disease and Hashimoto’s made a big dent in my misery. He also tested me for a plethora of food allergies, and several of them came up positive with antibodies. I was thrilled to FINALLY have some constructive way to fight against the misery that had been hounding me for years, but I was totally lost as to what to eat now that I was avoiding several major things. Fortunately I began renting a room quite soon after that, and their daughters had allergies very similar to mine, so my diet wasn’t an undue burden on them, and I learned how to dance the delicate dance that is food substitution. I’m proud to say that I became quite the accomplished cook. I wish that you had some kind of resource glossary for those who are newly diagnosed and absolutely lost. There are such things out there, of course, but it would be intriguing to see how a certified allergist tackled the issue.

    My constitution did slowly improve with the changes made, though stress and emotional upsets often brought on flares or relapses, and the next few years were the healthiest and happiest of my entire life. I do have two questions for you, though. Firstly, the endocrinologist that initially tested me said that if I avoided my allergens strictly enough then I could retake the test and no antibodies would show up for that specific food. It makes sense, but is it true? You said in your article that you will ALWAYS be allergic to something that is a true allergy, so I suppose that even if the antibodies were at zero through strict avoidance, one ingestion would bring the symptoms roaring right back to life. (Question 1.5: are people with existing autoimmune diseases more likely to have food allergies? Can one be a predictor for the other? It seems reasonable that it could…)

    That brings me to my second question. I’ve read in several places and from different sources that immune problems such as food allergies and auto immune diseases are due to “leaky gut syndrome”, and that if one heals their gut then the immune system will no longer see enemies in innocuous substances. What is your take on this?

    Than you again for your wonderful work. Allergies can be a very confusing topic to navigate without assistance, especially with so much contradictory information floating around it there. I stumbled upon one of your articles by accident, but I’ll be honest– I stayed and started reading other articles because of your sense of humor!

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