Peanut Allergies – Causes, Signs and symptoms

Peanut Allergies

Also called: Goober Allergies, Groundnut Allergies, Earthnut Allergies, Monkey Nut Allergies


A peanut allergy is a potentially deadly allergic reaction to the proteins found in peanuts. When an allergic individual comes into contact with a peanut protein (usually by eating, though much less commonly by touching or inhaling the protein) the immune system triggers an allergic response. The only way to successfully treat a peanut allergy is to completely remove peanuts and products containing peanuts from the diet.

Peanut allergies are one of the most common causes of food-related deaths. Individuals who are sensitive to peanuts can go into anaphylactic shock after ingesting even a trace amount of peanut protein. Roughly 100 people die each year in the United States as a result of food–related anaphylactic shock, according to the American Academy of Allergy, Asthma and Immunology (AAAAI). Patients who are at risk for this potentially deadly allergic reaction are often advised to carry an epinephrine shot (allergy kit) by their physician. Epinephrine helps to reverse the severe breathing problems associated with anaphylactic shock and raises blood pressure.

It is important to note that peanuts are not actually nuts but part of the legume family (along with peas, beans and lentils). Peanuts do not belong to the tree nut family that includes cashews, almonds, pecans, walnuts, beechnuts, Brazil nuts, pistachios and more. Tree nut allergies are less common than peanut allergies.

Approximately 3.3 million people in the United States have an allergy to peanuts and/or tree nuts, and roughly 1.5 million people suffer from a severe allergy to peanuts in the United States, according the AAAAI. Though many types of food allergies are outgrown after childhood, only about one in five people outgrow an allergy to peanuts. A few individuals will find that their allergic response diminishes over time, though the majority of people with peanut allergies will need to carefully avoid peanut and peanut products throughout life. Only a physician is qualified to determine whether a person can reintroduce peanuts to the diet.

Symptoms of a peanut allergy usually include swelling, hives, itchiness, redness, nausea and stomach pain. Treatment of the symptoms associated with peanut allergies usually involves the use of medications, such as antihistamines and bronchodilators.

The development of a peanut allergy is believed to occur for most during infancy. Dietary exposure at a young age may result in allergy development in some individuals. People with a family history of allergies are more likely to develop a peanut allergy.

New developments in peanut allergy treatment are making it possible for some individuals to accidentally consume several peanuts without having a reaction. Though this treatment is not considered a cure, and does not allow a patient to knowingly consume peanuts, it does reduce the threat of accidental consumption under which many people with this allergy are forced to live.

About peanut allergies

A peanut allergy is one of the most common types of food allergies, and is a very serious condition that can result in death. It occurs when a person’s immune system overreacts to exposure to peanuts or products with peanut proteins. According to the American Academy of Allergy, Asthma and Immunology (AAAAI), about 1.5 million people suffer from a severe peanut allergy. The only way to successfully treat a peanut allergy is to completely remove peanuts and foods containing peanuts from the diet.

Peanuts are actually part of the legume family (along with peas, beans and lentils) and are a type of seed. About a quarter of the peanut kernel is made up of proteins, many of which are known allergens. Almost half of those individuals who are allergic to peanuts also have cross-reactivity to some form of tree nuts.

Allergic individuals who have been exposed to a peanut protein will usually begin to experience symptoms in a few minutes to a few hours. Symptoms include swelling, hives, itchiness, nausea and stomach pain. Severe reactions can result in anaphylactic shock, which includes difficulty breathing and a drop in blood pressure.

The body response that occurs when an allergic individual encounters a peanut protein is called an allergic cascade and includes the following steps:

  • The immune system responds when a peanut protein enters the body. This usually occurs by eating peanuts or peanut components. However, in some individuals it can also occur through skin contact or even inhaling peanut fumes.

  • The immune system reacts by perceiving the protein to be a dangerous threat. To combat the threat, the body triggers the release of IgE antibodies.

  • The IgE antibodies trigger the release of histamines and other chemicals from mast cells and basophils. It is these chemicals that are responsible for most allergy symptoms.

For reasons that are not yet known, peanut allergies can be triggered by a very tiny amount of peanut protein – much less than for any other type of food allergy. As a result, peanut allergies can be triggered very easily. Some highly sensitive individuals can have an allergic response simply by kissing or having skin to skin contact with another person who has recently eaten peanuts.

Some foods that are packaged in the same facilities as peanuts, but do not contain any peanut ingredients themselves, may cause reactions in highly sensitive individuals. Therefore, food packaging may indicate that the food was processed on equipment that also processed foods containing peanuts. This statement will not be in the ingredient section, but may appear on the food label. The U.S. Food and Drug Administration does not require this notice to appear on food labels, but does encourage its use. When in doubt about a product, consumers are encouraged to contact the manufacturer.

Even thermal and chemical treatment of the peanuts (as occurs with cooking or processing) is not effective at reducing the strength of peanut allergens. Occasionally, these processes will even increase the allergen’s strength. Again, this is different from most other food allergies, in which cooking or chemically treating foods tends to reduce the allergic response.

A number of recent studies have shown that the prevalence of peanut allergies is growing in children. While there is currently no conclusive explanation for this phenomenon, many researchers attribute the trend to the rising numbers of children who are eating peanuts at a very young age. Exposure to an allergen at a young age may lead to the development of an allergy to that substance.

Another theory for this increase involves the peanuts themselves. Some believe that processes used to prepare peanuts (e.g., roasting) are making them more likely to trigger allergic reactions. Finally, peanuts are being used in increasing numbers of products, such as topical creams, which may also contribute to the increase in allergies.

Although the incidence of peanut allergies in children is on the rise, up to 20 percent of young children outgrow their peanut allergy. Studies have not been conducted on older individuals.

Potential causes of peanut allergies

Sensitive individuals need to educate themselves on all forms of peanuts so they can carefully avoid problem foods. Common foods and ingredients that contain threatening peanut proteins include:

  • Peanut butter
  • Cold-pressed or expressed peanut oil
  • Peanut flour
  • Hydrolyzed plant protein
  • Hydrolyzed vegetable protein
  • Groundnuts
  • Earthnuts
  • Monkey nuts
  • Mixed nuts
  • Arachis oil
  • Groundnut oil
  • Natural flavoring

Peanuts are included in many types of food that seem unlikely to have peanuts as an ingredient. Foods and products that very often contain hidden peanut products include:

  • Breakfast cereals
  • Biscuits
  • Pastries
  • Cookies
  • Crackers
  • Ice cream
  • Desserts
  • Cereal bars
  • Nutrition and energy bars
  • Curry or satay sauces
  • Candies
  • Salad dressings
  • Chinese, Indonesian, Thai, Vietnamese, Mexican and African dishes
  • Vegetarian dishes
  • Marzipan
  • Soups
  • Topical ointments

People with peanut allergies should also avoid foods that list artificial nuts as an ingredient. These may be peanuts that have been deflavored and reflavored to taste like a tree nut. For instance, mandelonas are peanuts that have been soaked in almond flavoring.

Some people are very responsive to even trace amounts of peanut proteins. In these individuals, even touching another person who has recently consumed peanuts can bring on a reaction. These sensitive individuals must be very careful not to have skin contact with any type of peanut product and should also be careful not to inhale the fumes produced by cooking peanuts. Inhaled peanut fumes can cause symptoms associated with allergic rhinitis (hay fever) in some individuals.

In some cases, food packaging may include a statement that the food was processed on equipment that also processes foods containing peanuts. However, this statement is not required to appear on food labels by the U.S. Food and Drug Administration. When in doubt about a product’s ingredients, consumers are encouraged to contact the manufacturer.

Related allergies and conditions

A peanut is part of the legume family, although they make up their own branch of the legume family tree. People allergic to peanuts may also be allergic to other legumes. This is called a cross-reaction.

Though cross-reactions are not common, they can be just as dangerous as a reaction to peanuts. Other types of legumes should be avoided by peanut-allergic individuals until a physician has determined whether a cross-reactive condition is present. Peanut-allergic individuals should avoid eating:

  • Soybeans
  • Peas
  • Kidney beans
  • Lentils
  • Butter beans
  • Lima beans
  • Chickpeas
  • Black-eyed peas
  • Green beans

Anyone who has sensitivity to peanuts or other legumes may also be sensitive to unrefined soybean oil, and should avoid the substance.

A peanut allergy should not be confused with a tree nut allergy. Tree nuts are large, edible seeds of trees and include walnuts, cashews, almonds, pecans, Brazil nuts, beechnuts and pistachios. Tree nut allergies are less common than peanut allergies. However, about half of adults who are allergic to peanuts are also allergic to a type of tree nut.

The relationship between different types of nut allergies is not completely understood.  Therefore anyone allergic to peanuts should use caution when consuming tree nuts. Physicians may recommend that patients with peanut allergies also avoid tree nuts as a precaution.

In addition, people with peanut allergies may also be allergic to seeds (e.g., sesame).

Some research suggests that a cross-reaction can occur between peanuts and lupin flour, which is a cooking ingredient that is becoming increasingly popular in pasta and in bread products. Individuals with peanut allergies should avoid any products that contain lupin flour until they have had an allergy test that can confirm or rule out lupin sensitivity.

Some peanut-allergic individuals may find they also have oral allergy syndrome, which is characterized by an itching, tingling or swelling in the lips, tongue, palate or throat after eating certain foods. Usually, this condition involves a relationship between a specific type of food allergy and certain types of pollen (for example, ragweed allergies and oral allergies to ingested bananas and melons often coincide). A cross–sensitivity between the similar proteins found in the food and pollen are usually to blame.

Signs and symptoms of peanut allergies

Exposure to peanuts can trigger a host of allergic responses in sensitive individuals. Symptoms typically appear within minutes of eating a peanut or peanut product, although some reactions are known to occur up to several hours later. Reactions to a food allergen can range from mild anaphylaxis (allergic reaction involving two or more body systems) to severe and potentially life–threatening anaphylactic shock. There is no way to predict the severity of reaction when a person with food allergies ingests the problem foods. Therefore, even people experiencing mild symptoms should immediately use an allergy kit and then seek medical treatment.

Mild to moderate symptoms of an allergic food reaction may include:

  • Skin problems. Includes swelling, hives, itchiness and redness

  • Throat and breathing problems. Includes hoarseness, difficulty swallowing, shortness of breath, wheezing and repetitive coughing

  • Circulation problems. Includes paleness, dizziness, low blood pressure and loss of pulse

  • Gastrointestinal problems. Includes stomach pain, nausea, vomiting and diarrhea

Mild to moderate symptoms may progress rapidly to more severe symptoms. It is also possible for severe symptoms to appear even when mild to moderate symptoms are not present. Symptoms of a more severe reaction include:

  • Severe shortness of breath
  • Tightening in the chest or throat
  • Choking
  • Loss of consciousness

Diagnosis methods for peanut allergies

The methods used to diagnosis peanut allergies are very similar to those used in other food allergies. Physicians will generally start by asking a patient about their medical history and will perform a physical examination to rule out any conditions with similar symptoms. To better determine what type of food is the allergen, the physician will often have patients keep a food diary of everything they eat over a period of weeks or months. This will help demonstrate a correlation between a certain type of food and the onset of allergy symptoms.

  • Skin test. This test involves scratching, pricking or injecting an individual’s skin with a peanut extract. The tested area will react with redness or swelling to indicate an allergic response. This test can be too dangerous to use on highly sensitive individuals. Recent research has helped to increase the effectiveness of this type of test when diagnosing peanut allergies.
  • RAST (radioallergosorbent test). This blood test allows a laboratory to detect antibodies that correspond to a peanut allergy in a sample of the patient’s blood. While less accurate than skin testing, it can be used on those people who have reactions that are too sensitive for a skin test.

  • Blinded food challenge test. This is considered the most effective way of determining the cause of a food allergy because it supplies the most convincing results. Different foods are placed within capsules to hide their identity. The patient consumes the capsules and the physician looks for signs of an allergic reaction. This type of test is time–consuming and difficult. It is often reserved to confirm suspicions that a patient’s symptoms are not caused by a food allergy. This type of test should only be performed in the presence of a physician who can treat anaphylaxis.

  • Elimination diet. This method involves removing peanuts from an individual’s diet for several weeks to see if allergic reactions persist. If symptoms stop, it can be presumed that peanut allergy was the cause. The food may then be briefly reintroduced to the patient’s diet in a controlled, clinical setting. If symptoms resume, the diagnosis of peanut allergy is confirmed.

Treatment and prevention for peanut allergies

The only effective treatment for individuals with peanut allergies is the complete avoidance of peanuts and foods with peanuts. This means constant vigilance when buying food in a grocery store, eating at a friend’s house or eating out at a restaurant. Allergic individuals must always check the labels of the foods they purchase and inquire about food preparation and ingredients when they are eating away from home. Accidental exposure to peanut proteins can be fatal.

Because eating just a trace amount of peanut protein can trigger an allergic response, allergic individuals must be very careful of what types of foods they consume. Many types of foods contain peanuts, even if the ingredients do not specifically list them. Allergic individuals should educate themselves on some of the other names of peanut ingredients (e.g., hydrolyzed vegetable protein) as well as some of the other names of the peanuts themselves (e.g., groundnuts).

When reading labels, patients should avoid products with unfamiliar ingredients because the substance may be a derivative of peanuts. Many manufacturers offer customer service lines to answer questions regarding their products. Commonly printed on product packaging, these phone numbers enable individuals to inquire about ingredients, as well as other concerns.  

Recent legislation may make it easier for people to determine if a food item contains a potential allergen. As of January 2006, food manufacturers are required by the Food & Drug Administration (FDA) to clearly list food allergens on their product labels.

People need to be careful of not only ingredients, but food preparation methods as well. Kitchen utensils that come into contact with peanuts can accidentally spread peanut molecules into other foods when not properly cleaned between uses.

Tips to avoid exposure to peanuts while dining out include:

  • Keep restaurant orders simple. Baked and broiled items and single food items are better choices than items with many ingredients. For example, a baked potato is a better choice than potato souffle, which may contain unknown ingredients.

  • Avoid creams, dressings, sauces and toppings.

  • Avoid salad bars and buffet lines. Serving utensils are often used interchangeably in these serving situations.

  • Avoid ethnic foods that usually contain peanuts (e.g., African, Asian)

  • Take special note when ordering dessert. Nuts may be used, even if not indicated on the menu.

  • Avoid asking the waiter or waitress about the ingredients used in the dishes. Only the owner or the person overseeing the kitchen should be approached.

In the case of children with peanut allergies, schools, daycare facilities and clubs all need to be informed of the child’s condition. Schools should work closely with the parents to make sure the child does not accidentally come into contact with peanuts in the cafeteria or the classroom. Many schools have already banned peanuts and peanut products from their facilities. Babysitters, grandparents, and the parents of friends should all be advised of the child’s allergy and should be taught emergency treatment procedures.

People with peanut allergies are often given an allergy kit that includes epinephrine. Epinephrine is a synthetic form of adrenaline that, when injected, works as a powerful bronchodilator, opening breathing tubes and restoring normal respiration quickly. It also raises blood pressure. Epinephrine is usually reserved for the most severe allergic reactions that involve anaphylactic shock. However, when in doubt over whether a reaction is severe enough to warrant an epinephrine shot, experts typically recommend to take the shot. Most physicians recommend that patients susceptible to severe peanut reactions carry an injection of epinephrine with them at all times and understand how to self-administer the drug. A medical alert bracelet or necklace is also a good idea for these individuals.

Activated charcoal is effective at reducing the severity and progression of an allergic reaction. The therapy works by binding to the major allergens in the peanut, blocking the allergens from interacting with the immune system and preventing allergy symptoms. This type of therapy is not suitable for treating a peanut allergy response by itself. It should be used only after another type of more effective treatment (e.g., epinephrine) has been administered.

A new therapy known as TNX-901 is showing effectiveness at disrupting allergic reactions from peanuts. Though still being tested by the FDA for use within the United States, the therapy may allow people to tolerate several peanuts worth of allergens without a reaction. It works by blocking IgE, which is an antibody that facilitates an allergic reaction. By interfering with IgE, TNX-901 effectively prevents the allergic cascade from taking place. Monthly shots of the drug would allow a person to tolerate only a very limited exposure to peanuts (about one to nine nuts). This therapy is not designed to be a cure, but should allow peanut-allergic individuals more breathing room in the event of an accidental exposure.

Symptom relief for peanut allergy reactions

The only effective treatment for a food allergy is the complete removal of food allergens from the diet. The diligent practice of avoidance is a necessity for anyone suffering from a food allergy.

Once an allergic reaction to a food has occurred, and an allergy kit has been used, there are some alternatives for the relief of allergy symptoms. These medications can help relieve symptoms somewhat, but are by no means a cure for the condition. These medications should not be viewed as a countermeasure or effective antidote for food allergies, and an allergy kit should always be used at the first sign of a food allergy reaction. Only avoidance of problem foods can successfully treat a food allergy.

While some medications for the relief of allergy symptoms are available over–the–counter, they should be used only under the direction of a physician. Some medications that may be recommended include:

  • Antihistamines. Medications that provide relief for more basic allergy reactions such as hives, sneezing, runny nose and gastrointestinal symptoms.

  • Bronchodilators. Medications that open the airways of the lung, relieving symptoms such as shortness of breath or wheezing.

  • Corticosteroids. Medications that reduce inflammation. These drugs are often taken regularly to prevent an allergic attack or reduce the severity of symptoms.

Questions for your doctor on peanut allergies

Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about peanut allergies:

  1. What tests will you use to determine if I am allergic to peanuts?
  2. What treatment options are available to me?
  3. Is it safe to consume a small amount of peanuts?
  4. What should I do if I accidentally consume peanuts?
  5. What products commonly include peanuts? What terms should I look for when reading an ingredient label?
  6. Is it safe to handle peanuts or prepare peanut dishes for my family?
  7. What is the best way to prevent an allergic reaction while dining out?
  8. Is my child likely to outgrow their peanut allergy?
  9. How will you determine if the peanut allergy has been outgrown?
  10. Are my children more likely to develop peanut allergies because I have the condition?
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