Symptoms of a Mushroom Allergy

Mushrooms are a versatile and tasty addition to the diet, whether accenting foods or taking center stage at a meal. While many people enjoy mushrooms, this fungi can cause allergic reactions in a small percentage of connoisseurs. Symptoms may arise from eating, inhaling or simply having skin contact with mushrooms. If you have a mushroom allergy, inform your doctor so you can understand how to prevent and treat reactions.

Mushroom Allergies

There are at least 140,000 species of mushrooms in the world, and a majority of these have not yet been the subject of allergy research. As a result, the full spectrum of mushroom allergy symptoms is not yet known. However, mushroom allergies are considered rare -- and unique because this fungi can invoke symptoms not only from ingestion, but as a result of skin contact or from inhalation of airborne spores, which are like microscopic seeds. A mushroom allergy is not the same as mushroom poisoning, which can be a fatal response to the toxins in poisonous mushrooms.

Respiratory Symptoms

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When tiny, airborne mushroom spores are inhaled, an allergic response that affects the respiratory system can follow. The related symptoms may include sneezing, coughing, runny nose, sinus congestion, along with itching of the eyes, ears, mouth and throat. These reactions are like seasonal allergy symptoms, and can be particularly bothersome when mold counts are high. Respiratory allergy to mushroom spores has also been noted in workers who select, pack and prepare mushrooms, causing asthma symptoms including difficulty breathing, wheezing and coughing.

Skin Symptoms

Food allergies can trigger hives, which are red, swollen, and itchy areas on the skin, and a dry, itchy rash. Due to limited published research on mushroom allergy symptoms, the frequency of hives is not known. However, case reports of contact dermatitis, a skin rash that causes swelling, itching and redness of the affected skin, have been described. One report linked occupational handling of shiitake mushrooms to allergic contact dermatitis, a skin rash caused by contact with an allergen. Another report linked cases of contact dermatitis to several different mushroom species. Shiitake dermatitis is another skin reaction to raw or undercooked shiitake mushrooms, although this dermatitis is caused by the toxin lentinan, which is inactivated by cooking, and not by an allergy.

Mouth and Throat Symptoms

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Oral allergy syndrome (OAS) occurs when people with allergies to pollen, for example, have an allergic response to similar proteins found in certain raw fruits and vegetables. OAS from eating mushrooms has also been documented. Typical OAS symptoms include swelling or itchiness of the mouth, face, lip, tongue and a scratchy throat. These symptoms start within an hour of eating the fruit or vegetable and usually resolve within 30 minutes.

Severe Reactions After Eating

Rarely, severe allergic reactions occur after eating mushrooms. These allergies have been seen in people with previously known respiratory allergies to mold or OAS from mushrooms, but severe reactions can also occur in people who have not had a prior allergic response to mushrooms. In addition to respiratory and skin symptoms, food allergies can lead to nausea, stomach pain, vomiting and diarrhea. However, because mushroom allergies are rare, the full range of gastrointestinal symptoms from ingestion is not known.

The most severe consequence of food allergies -- anaphylaxis -- can occur after eating mushrooms. This life-threatening reaction, which warrants immediate medical attention, causes a drop in blood pressure, a weak pulse, trouble swallowing or breathing, lightheadedness, turning blue or fainting, and can swiftly progress to respiratory and cardiovascular failure -- and can cause death.

Warnings

Tell your doctor if you have respiratory, skin or gastrointestinal symptoms after eating mushrooms. If you do have an allergy to mushrooms, it's important to have a treatment plan which may include carrying a medicine called epinephrine, which is used to treat anaphylatic reactions. It's also essential to understand the foods and ingredients you need to avoid, so reading food labels is important before you consume any processed foods. If you have any symptoms of anaphylaxis, use your epinephrine according to your doctor's plan, and seek immediate medical attention.

Reviewed by Kay Peck, MPH RD