Can a Mushroom Allergy or Intolerance Cause Digestive Issues?

If you experience gastrointestinal symptoms after eating mushrooms, it may be a sign of a mushroom allergy (an immune condition that causes allergic symptoms) or a food intolerance. If mushrooms trigger an allergic reaction, your digestive system can be involved. A food allergy may cause digestive symptoms like nausea, vomiting, and diarrhea, according to Cleveland Clinic. It can also trigger a potentially life-threatening reaction called anaphylaxis.

You may also experience allergic reactions or anaphylaxis with digestive symptoms after eating mushrooms if you have a type of immune system dysfunction called mast cell activation syndrome (MCAS), according to research. In MCAS, you don’t have an allergy to mushrooms specifically, but harmless substances can trigger your immune system. This can cause digestive symptoms like bloating, diarrhea, constipation, nausea, vomiting, belly pain, and heartburn.

A food intolerance is also a possibility if you experience gastrointestinal symptoms related to eating mushrooms, per Cleveland Clinic. When your digestive system can’t break down certain foods, you may experience symptoms such as gas, bloating, diarrhea, belly pain, and an upset stomach.

Food intolerances can cause painful symptoms, but they’re never life-threatening.

Allergic Reactions

An allergy to mushrooms occurs when the immune system develops an antibody specific to a protein in the food, according to the American Academy of Allergy, Asthma, and Immunology. Along with other symptoms, an allergic reaction to a food allergy might trigger uncomfortable digestive symptoms:

• Vomiting
• Diarrhea
• Belly cramps

When your immune system detects the protein, it releases immunoglobulin E (IgE) antibodies. Your immune cells then release chemicals that cause an allergic reaction. Symptoms usually start within a few minutes to two hours after you eat the food, per MedlinePlus.

Allergic reactions can progress to anaphylaxis, which is life-threatening. Call 911 if you experience trouble breathing, an extreme drop in blood pressure, or a loss of consciousness.

According to Juniper Allergy in San Antonio, Texas, if you're allergic to mold, you may be more likely to experience a reaction when eating mushrooms than someone without a mold allergy. The same applies if you’re exposed to mold and have a mushroom allergy.

MCAS Symptoms

MCAS reactions involve symptoms in two or more organ systems, per Cleveland Clinic. It may cause these digestive issues:

• Bloating
• Diarrhea
• Constipation
• Nausea
• Vomiting
• Belly pain
• Heartburn

They may be more severe than typical allergic reactions and can occur within minutes or hours, or even be delayed up to 24 to 48 hours after a trigger, per Accurate Clinic in Kenner, Louisiana.

In addition to digestive issues, you may experience skin involvement like flushing or hives, respiratory symptoms like trouble breathing, or cardiovascular symptoms like increased heart rate or a drop in blood pressure.

Like IgE antibody-triggered allergies, these reactions may progress to anaphylaxis. If that happens, you'll require emergency medical attention.

Intolerance Symptoms

Food intolerances cause symptoms within a few hours of eating, per Cleveland Clinic. The amount of food you ingest may dictate how severe the reaction is — you may be able to tolerate a small amount of mushrooms, for instance. Most people who have a reaction to mushrooms have it because of a food intolerance.

Digestive symptoms of a food intolerance may include the following:

• Gas
• Bloating
• Diarrhea
• Nausea
• Abdominal pain
• Heartburn or reflux

It can also cause headaches or migraine. These symptoms, though they may be painful, are not life-threatening like allergic reactions.

Some people are intolerant to certain carbohydrates found in some mushrooms that are poorly absorbed by the gut, called FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols), according to IBS Clinics in London. Different mushrooms can have varying amounts of different types of FODMAPs.

However, if a person with a FODMAP intolerance eats a type of mushroom that contains FODMAPs, they may experience these digestive symptoms:

• Gas
• Bloating
• Belly pain

These intolerances can’t be confirmed via testing.

Allergy Testing

To determine whether you have an allergy to mushrooms, you need to see an allergist and discuss whether testing is appropriate. You may undergo skin and blood tests, as well as tests during which you eliminate or eat specific potential allergens, according to MedlinePlus.

• Skin Prick Test A small amount of the potential allergen’s protein is placed on your skin. Your doctor pricks your skin with a needle, allowing the liquid to enter the skin’s layers. Afterward, check for a red, itchy bump, which may suggest an allergy.
• Allergy Blood Tests These measure IgE antibodies in your blood. With food allergies, antibody levels specific to that food may be higher than usual, but IgE levels alone can’t confirm an allergy or its severity.
• Oral Food Challenge Test This occurs under close supervision, and it’s the most accurate food allergy test. During the test, you’ll slowly eat increasing amounts of the suspected allergen. If you don’t react to the food, you don’t have an IgE antibody-mediated allergy. Having a reaction confirms the allergy, so you’ll receive immediate treatment.

It’s possible to have both IgE-mediated allergies and MCAS, according to research.

Testing for MCAS

To diagnose MCAS, a physician will consider multiple elements.

First, you must have a history of recurrent episodes of severe reactions affecting two or more organ systems. Your allergist or immunologist will administer urine and blood tests that measure the levels of chemicals released by mast cells or what remains in your system after they break down.

Your doctor will also consider your response to medications that block the absorption or prevent the release of mast cell chemicals, such as antihistamines, mast cell stabilizers, and certain biologic medications. If these medications prevent or lessen reactions, a diagnosis of MCAS is supported.

Diagnosis and Next Steps

Different reactions to mushrooms require different treatments and testing methods.

Mushroom Allergy

If you test positive for a mushroom allergy, your doctor will recommend that you stop eating all types of mushrooms, as well as powders, supplements, broths, and seasonings that are mushroom based, per Juniper Allergy.

Mushrooms can be hidden in unexpected foods, such as meat substitutes, so always check labels. You’ll be prescribed an epinephrine auto-injector (EpiPen) or nasal spray (Neffy), as even mild reactions can progress into anaphylaxis, according to the Food Allergy and Anaphylaxis Connection Team.

MCAS

If you’re diagnosed with MCAS, you’ll need to avoid triggers. Per Mast Cell Action, triggers can change over time — what sets off symptoms now may not bother you later. Additionally, MCAS follows a relapsing-remitting pattern, meaning there will be periods of flare-ups and times when you experience few if any symptoms, according to research.

As with an IgE allergy, you’ll be prescribed epinephrine in case of emergencies. Treatments include the following:

• Antihistamines
• Mast cell stabilizers like cromolyn sodium (Gastrocrom)
• Omalizumab (Xolair)
• Leukotriene modifiers such as montelukast (Singulair)
• Tyrosine kinase inhibitors such as midostaurin (Rydapt)
• Corticosteroids

An MCAS treatment plan often includes multiple medications, as well as an anti-inflammatory diet and foods and supplements that contain quercetin and vitamin C, says Tania Dempsey, MD, an MCAS specialist at the AIM Center for Personalized Medicine in Purchase, New York.

Because MCAS can be hard to diagnose and treat, and stress is a possible trigger, many people are advised to try lifestyle modifications like stress management, regular exercise, and improved sleep hygiene.

Mushroom Intolerance

If you have a mushroom intolerance, you’ll need to limit or eliminate them from your diet, per Cleveland Clinic. You may be able to tolerate mushrooms in small amounts, however. When symptoms occur, medications such as antidiarrheals and antispasmodics can help.