Although nearly any food can trigger an allergy, only eight foods (wheat, fish, shellfish, milk, peanuts, tree nuts, soy, and egg) account for 90% of all food-allergic reactions in the United States. About 3% of the US population is allergic to onions.
A person is said to be allergic to a particular food if his body reacts in an undesirable manner every time he eats that food. In case of onion allergy, the immune system of the person reacts abnormally to the protein in onions. It identifies the protein as a dangerous substance, and tries to destroy it. It produces antibodies called IgE, which react against the protein in the vegetable. To protect the body from this strange situation, excessive amount of histamine is produced in the gut, pharynx, and skin. As the body reacts adversely to too much of histamine, the person starts sneezing or has skin rashes, sore throat, and watery eyes. This is described as an allergic reaction. It has been noticed that raw onions are more likely to cause an allergic reaction than cooked ones. Though, allergy to onions is not as common as peanut or shellfish allergy.
Although the symptoms of onion allergy and intolerance are almost similar, allergy symptoms are usually noticed quickly, sometimes within a minute after consumption of onions. Sometimes, the reaction can be severe and life-threatening too. In case of onion intolerance, the reaction is relatively mild and slow. The person may suffer from stomach upset, stomach cramps, bloating, swelling on the face, diarrhea, etc. The symptoms may not be noticed immediately. They can even be noticed one day after consumption of onions.
✦ Sneezing, runny nose
✦ Sinus pain
✦ Sore throat, cough
✦ Difficulty sleeping
✦ Rashes, itchy reddened skin, dry skin flakes
✦ Itchy, watery eyes
✦ Skin inflammation, swelling
✦ Facial flushing
✦ Bloating, excess gas, diarrhea
✦ Heartburn, acid reflux
✦ Nausea and vomiting
✦ Burning sensation on the mouth
✦ Skin hives
✦ Swollen lips and tongue
✦ Mouth, tongue, and gum blisters
✦ Puffy eyes
✦ Swelling in throat, difficulty swallowing
✦ Difficulty breathing
✦ Chest tightness
✦ A metallic taste in mouth
✦ Anaphylaxis (rare): It is a rare (when it comes to onion allergy) but acute reaction which seriously affects the breathing and heart rate of an individual. The person cannot breathe easily. His/her blood pressure drops and he/she faints. He or she may feel dizzy and may not be able to describe what is happening to himself/herself. It is a serious medical condition.
✦ In most cases, antihistamines help relieve the allergy symptoms in a short period of time.
✦ Over-the-counter antihistamines can be taken to get rid of mild symptoms.
✦ Doctors usually prescribe steroids for serious allergic reactions. As steroids come with serious side effects, instructions regarding dosage and the time period for which they are to be taken should be followed strictly.
✦ Those who have been diagnosed with onion allergy should always carry antihistamines with them. If they feel that the food consumed has triggered the allergy, then they should immediately take the medicine.
✦ Ointments and corticosteroids are helpful when the symptoms are limited to skin reactions like rashes or boils.
✦ Aloe vera gel, when applied topically, can help soothe the burning sensation on the skin. This is one of the best home remedies for skin rash.
✦ The allergy may aggravate the symptoms of asthma. One who experiences breathing difficulty after being exposed to onions can use an albuterol inhaler. It would help alleviate the symptoms.
✦ Foods like almonds can neutralize stomach acids, and can help lower symptoms like heartburn and acid reflux.
✦ Avoiding onions would be the best treatment, as it would help eradicate the root cause of the allergy. Those who are allergic to onions need to take precautions while choosing their food in restaurants or in supermarkets. They should read the labels or menu description carefully.
✦ Anaphylaxis, being a serious medical condition, one should seek immediate medical attention. An epinephrine injection should be immediately given to the person suffering from an anaphylactic shock.
The following tests can be performed to find out the allergen or to confirm the diagnosis of onion allergy.
- Patch test
- Skin prick test
- Intradermal test
- IgE blood test
Both children and adults can be allergic to onions. They can be allergic to garlic, chives, and other members of the Allium family too. Onions are widely used for cooking; it is added to soups, sauces, salads, curries, cheeses, vegetable juices, broth, stock, salad dressings, and various vegetarian and non-vegetarian dishes. People with such an allergy should always go through the list of ingredients.
The degree of an allergic reaction may vary from person to person. It depends on how sensitive the person is to onions. Usually, the symptoms go away when the allergen is expelled from the body. But in a few hypersensitive individuals, they can last for days, even after the expulsion of onions from the body.