What is it?
Peanut allergy is common, especially in children. Peanut allergy symptoms can range from a minor irritation to a life-threatening reaction (anaphylaxis). For some people with peanut allergy, even tiny amounts of peanuts can cause a serious reaction.
If you or your child has had a reaction to peanuts, tell your doctor about it. Peanut allergy is one of the most common causes of severe allergy attacks. It's important to get even a minor reaction to peanuts checked out. Even if you or your child has had only a mild allergic reaction in the past, there's still a risk of a more serious future reaction.
An allergic response to peanuts usually occurs within minutes after exposure, and symptoms range from mild to severe. Peanut allergy symptoms can include:
- Skin reactions such as hives, redness or swelling
- Itching or tingling in or around the mouth and throat
- Digestive problems such as diarrhoea, stomach cramps, nausea or vomiting
- Tightening of the chest
- Shortness of breath or wheezing
- Runny or stuffy nose
Peanut allergy is one of the most common causes of anaphylaxis, a medical emergency that requires treatment with an epinephrine (adrenaline) injector and a trip to the emergency room.
Anaphylaxis signs and symptoms can include:
- Constriction of airways
- Swelling of your throat that makes it difficult to breathe
- A severe drop in blood pressure (shock)
- Rapid pulse
- Dizziness, lightheadedness or loss of consciousness
Peanut allergy occurs when your immune system mistakenly identifies peanut proteins as something harmful. When you have direct or indirect contact with peanuts, your immune system releases symptom-causing chemicals into your bloodstream. It isn't known exactly why some people become allergic to peanuts and others don't.
Exposure to peanuts can occur in different ways:
- Direct contact. The most common cause of peanut allergy is eating peanuts or peanut-containing foods. Sometimes direct skin contact with peanuts can trigger an allergic reaction.
- Cross-contact. This is the unintended introduction of peanuts into a product. It's generally the result of a food being exposed to peanuts during processing or handling.
- Inhalation. An allergic reaction may occur if you inhale dust or aerosols containing peanuts, such as that of peanut flour or peanut oil cooking spray.
Food allergy vs. food intolerance
In some cases, what may appear to be a food allergy may actually be a food intolerance. Unlike a true food allergy, a food intolerance doesn't involve the immune system. With a true food allergy, even tiny amounts of the food can cause a severe reaction. In most cases, someone who has a food intolerance can eat small amounts of the food with only mild symptoms, such as indigestion or heartburn.
It isn't clear why some people develop allergies while others don't. However, people with certain risk factors have a greater chance of developing peanut allergy.
Food allergy risk factors include:
- Age. Food allergies are most common in children, especially toddlers and infants. As you grow older, your digestive system matures and your body is less likely to react to food that triggers allergies.
- Past allergy to peanuts. Some children with peanut allergy outgrow it. However, even if you seem to have outgrown peanut allergy, it may recur.
- Other allergies. If you're already allergic to one food, you may be at increased risk of becoming allergic to another. Likewise, having another type of allergy, such as hay fever, increases your risk of having a food allergy.
- Family members with allergies. You're at increased risk of peanut allergy if other allergies, especially other types of food allergies, are common in your family.
- Atopic dermatitis. Some people with the skin condition atopic dermatitis (eczema) also have a food allergy.
While some people think food allergies are linked to childhood hyperactivity and to arthritis, there's no evidence to support this.
Complications of food allergy can include:
- Need for special precautions. Because allergic reactions to peanuts are severe for many people, avoiding peanuts altogether is very important. This requires taking a number of steps to prevent accidental exposure.
- Anaphylaxis. Children and adults who've had a severe peanut allergy are especially at risk of having this life-threatening reaction.
The following may help determine if you have a peanut allergy or if your symptoms are likely due to something else, such as food intolerance, a bout of food poisoning or some other condition.
- Description of your symptoms. Be prepared to tell your doctor about your symptoms — such as exactly what happened after you ate peanuts, how long it took for a reaction to occur, and what amount of peanuts or food containing peanuts caused your reaction.
- Physical examination. A careful exam can identify or exclude other medical problems.
- Food diary. Your doctor may ask you to keep a food diary of your eating habits, symptoms and medications to pinpoint the problem.
- Elimination diet. If it isn't clear that peanuts are the culprit, or if your doctor suspects you may have a reaction to more than one type of food, an elimination diet may be needed. You may be asked to eliminate peanuts or other suspect foods for a week or two, and then add the food items back into your diet one at a time. This process can help link symptoms to specific foods. If you've had a severe reaction to foods, this method can't safely be used.
- Skin test. A skin prick test can determine your reaction to particular foods. In this test, small amounts of suspected foods are placed on the skin of your forearm or back. Your skin is then pricked with a needle, to allow a tiny amount of the substance beneath your skin surface. If you're allergic to a particular substance being tested, you develop a raised bump or reaction.
- Blood test. A blood test can measure your immune system's response to particular foods by checking the amount of allergy-type antibodies in your bloodstream, known as immunoglobulin E (IgE) antibodies. For this test, a blood sample taken in your doctor's office is sent to a medical laboratory, where different foods can be tested. However, these blood tests aren't always accurate.
Is it peanut allergy? Or is it peanut intolerance?
Not all reactions to peanuts are caused by an allergic reaction. It can be difficult to know whether you are allergic or intolerant to peanuts.
- If you have peanut intolerance, you might be able to eat peanuts with only mild symptoms, such as indigestion or heartburn, or no reaction at all. A peanut intolerance doesn't involve your immune system.
- If you have a true peanut allergy, eating even a small amount of peanuts may trigger a serious allergic reaction. Tests can help determine whether you have true peanut allergy.