Allergy to mushroom vs. GI intolerance to mushrooms

Author: V. Dimov, M.D., Allergist/Immunologist and Assistant Professor at University of Chicago
Reviewer: S. Randhawa, M.D., Allergist/Immunologist and Assistant Professor at NSU

A 34-year-old female is at the allergy clinic for evaluation of suspected allergy to mushroom. No history of allergic rhinitis, asthma, or atopic dermatitis.

Symptoms started 6 months ago, with abdominal pain and diarrhea within minutes of ingesting mushrooms (both cooked and raw mushrooms, portobello and button mushrooms). She has tried the same dishes with no mushrooms and there were no symptoms. She reports some milder symptoms when eating goat cheese and drinking beer.

Past Medical History, Past Surgical History, Family Medical History, Social History: Not contributory.

Review Of Systems: 12/14 systems were reviewed, negative apart from history of present illness above.

Physical Examination: Unremarkable.

Labs reviewed: ImmunoCAP IgE FEIA negative for multiple allergens, including champignon mushroom, and with low-normal IgE of 15.

What is the most likely diagnosis?

GI intolerance to mushrooms (portobello and button mushrooms). Food allergy to mushroom is unusual but can be seen. However, 80% of patients with food allergy have skin symptoms which she did not have. The history is suggestive of non-IgE mediated GI intolerance. As a precaution, Auvi-Q was prescribed until the workup is completed.

Percutaneous skin testing with indoor, outdoor, and food allergens was negative. The clinic did not have mushrooms available for prick-puncture test.

Differential diagnosis includes IBS or symptoms with histamine-rich food such as cheese and beer. None of these entities are IgE-mediated.

Helpful questions include:

Obtain a history of the exposure that includes the following:

- Quantity of mushrooms ingested
- Preparation of the mushroom (eg, raw or cooked)
- Source of the mushroom (eg, gathered outdoors or purchased via the Internet)
- Time of ingestion
- Any other people who may have ingested the same mushrooms
- Symptoms noted and time to onset of symptoms after ingestion
- Any other types of mushrooms that may have been ingested at the same meal
- Prehospital treatment, including home remedies
- Medications regularly taken
- Past medical history, with a focus on arrhythmias, asthma, prostatic hypertrophy, and gastric outlet obstruction

What management would you suggest?

Complete avoidance of mushrooms was suggested. As a precaution, Auvi-Q was prescribed until the workup is completed. In case of anaphylaxis, call 911.

Prick-puncture test with fresh mushrooms was suggested. If the test is negative, IgE-mediated food allergy to mushroom would be unlikely.

Differential diagnosis includes IBS or symptoms with histamine-rich food such as cheese and beer. None of these entities are IgE-mediated. The patient may benefit from GI evaluation.


Food and airborne allergy to mushrooms

Mushrooms are antigenically rich and that a species can have more than one allergen. The prevalence of mushroom allergy is not known. Aerospora of mushrooms and other woodland fungi, mostly basidiospores, occur in temperature zones in June to November, reaching maximum in August and September in quantities comparable to pollen and mold spores. There are large local and annual variations in species and spore concentrations in different milieus. In SPT and BPT studies about two dozen of these species have been associated with inhalant type I allergy.

Mushroom toxicity

There are thousands of species of mushrooms, but only about 100 species of mushrooms cause symptoms when eaten by humans, and only 15-20 mushroom species are potentially lethal when ingested.

Occupational exposure to mushrooms

Exposure to mushroom spores may cause many respiratory allergic diseases. In a 3-year study over 90% workers in a mushroom factory were sensitized to the spore, 40% quit because of the symptoms and 5% developed hypersensitivity pneumonitis (HP). It was suggested that workers should be counselled about the risk of mushroom allergy and precautionary measures should be taken to prevent its occurrence.

Histamine intolerance and histamine-rich foods

Histamine intolerance results from a disequilibrium of accumulated histamine and the capacity for histamine degradation. Histamine is a biogenic amine that occurs to various degrees in many foods. In healthy persons, dietary histamine can be rapidly detoxified by amine oxidases, whereas persons with low amine oxidase activity are at risk of histamine toxicity. Diamine oxidase (DAO) is the main enzyme for the metabolism of ingested histamine.

The ingestion of histamine-rich food or of alcohol or drugs that release histamine or block DAO may provoke diarrhea, headache, rhinoconjunctival symptoms, asthma, hypotension, arrhythmia, urticaria, pruritus, flushing, and other conditions in patients with histamine intolerance. Symptoms can be reduced by a histamine-free diet or be eliminated by antihistamines.

Foods rich in histamine

Fish (frozen/smoked or salted/canned)
Meat, sausage, salami, ham
Vegetables - Sauerkraut, Spinach, Eggplant, Tomato ketchup
Red wine vinegar

Foods with suggested histamine-releasing capacity

Citrus fruit

Egg white



Mushroom allergy. Koivikko A, Savolainen J. Allergy. 1988 Jan;43(1):1-10.

Mushroom Toxicity. Medscape.

Three-year follow-up study of allergy in workers in a mushroom factory. Tanaka H, Saikai T, Sugawara H, Tsunematsu K, Takeya I, Koba H, Matsuura A, Imai K, Abe S. Respir Med. 2001 Dec;95(12):943-8.

Histamine and histamine intolerance. Laura Maintz and Natalija Novak. Am J Clin Nutr May 2007 vol. 85 no. 5 1185-1196.

Published: 05/12/2013
Updated: 02/01/2014


Anonymous said...

This was a great post. I found the information very useful.

Anonymous said...

I have had the same reaction to mushrooms beginning in my late 30's. It is extremely painful and frightening. It took a mushroom pizza and mushrooms with steak to identify the allergy.
I am super cautious when eating out now.

Aryana said...

I developed the same reaction in my 20's and to oysters at the same time. It took a few miserable experiences to figure it out! I am wondering if I can use medicinal mushrooms for their many health benefits, but am afraid to experiment :-(

Unknown said...

The patient may have a trehalose intolerance. It is a genetic condition that produces similar symptoms to lactose intolerance. Interestingly, trehalose is now being used more commonly in many food items because it acts as a preserving agent. Even more interestingly, this quirky sugar is being genetically grown into tomatoes and other produce to improve shelf life. Until someone studies the true incidence rates of trehalose intolerance, unlucky people (like me) cant just simply avoid mushrooms, we must now roll the dice whenever we eat any food that may be tainted with this sugar.
I wrote a blog about my experience