Time Frame

• Symptoms of mushroom allergies usually arise within 20 to 30 minutes of first ingesting the fungus.
  
  

Itchiness

• Your skin may begin to itch or break out in hives once the mushroom is in your system.
  
  

Tissue Swelling

• Your hands and feet may swell and become painful and tender to the touch.
  
  

Difficulty Breathing

• A mushroom allergy may cause your air passages to close, resulting in shortness of breath or a constricted feeling in your chest.
  
  

Gastrointestinal Distress

• Gastrointestinal reactions to mushroom allergies can run the gamut from nausea to vomiting to diarrhea to stomach cramps.