People with food allergies develop irritating and, in some cases, life-threatening symptoms soon after eating the offending food. Symptoms of a food allergy range from hives to difficulty breathing. Developing a swollen tongue after eating can indicate a food allergy, but having a coating on your tongue does not.
A food allergy is an allergic reaction that occurs shortly after you ingest a certain food. Some food allergy symptoms are topical, while others are internal. Common foods that trigger food allergy symptoms are shellfish, fish, peanuts, tree nuts, eggs and milk. If you think you have a food allergy speak to your physician, as conditions such as food sensitivity or Celiac disease display symptoms similar to those for a food allergy.
A food allergy occurs when your immune system mistakes a particular food as a harmful substance. When the immune system detects a food as an allergen, it produces antibodies to protect your body from the invader. When you ingest the same food again in the future, your body reacts in the same way, in addition to producing histamine. The release of histamine causes symptoms such as itchy mouth, hives, facial swelling, wheezing, abdominal discomfort and dizziness.
A coated tongue isn't a symptom of food allergy, although it may occur after eating certain foods. Causes of a coated tongue are poor oral hygiene or vitamin and mineral deficiency. A coated tongue may appear white, black or yellow; each color signifies a different cause. A white coated tongue is normally caused by dehydration, nutritional deficiencies or an overgrowth of fungus in the mouth. A black coating on the tongue usually derives from smoking, bacterial overgrowth or poor oral hygiene. A yellow coating on the tongue is caused by problems in the gallbladder or liver. If you have a coating on your tongue despite practicing good oral hygiene, see your doctor for a diagnosis. Conditions such as jaundice, bacterial or fungal infections produce symptoms similar to those for food allergies.
If you develop symptoms of a food allergy after eating a specific food, seek emergency attention immediately. In some cases, food allergy symptoms progress to a more-severe allergic reaction known as anaphylaxis, which is life-threatening. Anaphylaxis causes symptoms such as constricted airway, trouble breathing, swollen throat, rapid pulse, shock, dizziness and loss of consciousness. If left untreated, anaphylaxis may lead to cardiac arrest. According to MayoClinic.com, people with hay fever or seasonal allergies may react to certain foods.