Peanut allergy

A food allergy is a hypersensitivity reaction that involves the immune system (see what is an allergy).  Although up to 20-30% of people believe they have a food allergy, studies show that between 2% and 5% of people suffer from a definite food allergy see food allergy.  Peanut allergy may cause the most problems of the food allergies because it is common, it is hard to avoid peanuts and in some people even tiny amounts can cause reactions.

Peanut is one of the most common causes of severe food allergy / anaphylaxis reactions.

  • Peanut allergy is becoming more common in countries such as the UK and USA, where about 1:50 children are now peanut allergic.
  • We do not have exact data about South Africa but it seems that peanut allergy has also increased here in recent years. There are many theories as to why this has happened, but we do not yet have clear answers.
  • The peanut is not actually a nut: it is a member of the bean (legume) family. It is related to soya beans, lentils, garden peas and chickpeas.
  • True “tree nuts” actually grow on trees, including pecan, hazelnut, walnut, almond, cashew, brazil and macadamia nut.
  • The proteins in peanuts are very different to those in tree nuts. Despite this about 30% of people with peanut allergy also react to one or more tree nuts. People with peanut allergy have about a 5-10% chance of also having reactions to legumes. Children with peanut allergy are also at higher risk of having egg allergy and sesame seed allergy.
  • Coconuts and pine nuts are seeds, not nuts. Most nut allergic people can eat them safely.
  • The most common type of peanut allergy is “immediate” type (IgE-mediated) food allergy.
  • This type of reaction typically occurs within minutes but may present up to 2 hours after eating the food.
  • Most allergic reactions to peanut and tree nuts are mild, causing hives, swelling or vomiting.
  • Some allergic reactions to nuts can be severe, causing difficulty in breathing due to throat swelling or asthma, or a drop in blood pressure. This is known as anaphylaxis.
  • Some peanut allergic people are sensitive to even tiny amounts of peanut. These people can have reactions from trace amounts, or even if someone who has recently eaten peanut gives them a kiss.
  • The first step is for the doctor to hear all the details about what was eaten and exactly what reactions occurred. This will help indicate whether the reaction was an allergy or not and if it was an allergy, what kind of reaction it was and whether it was mild or severe.
  • For immediate reactions a blood test and/or skin prick tests can be done to show the presence of the IgE antibodies. If these tests are negative an immediate type allergy is almost always ruled out. A “positive” result supports, but does not prove an immediate type food allergy, unless the values are very high.
  • Skin prick tests are done by placing a few drops of peanut (fresh peanut butter or specially manufactured peanut extract) on the skin and making a prick through the droplet see skin prick testing.
  • In cases which are uncertain, the allergist may recommend a supervised food challenge to test for peanut allergy. This entails giving initially tiny, then increasing amounts of peanut to the person in a controlled setting (see oral food challenge tests).
  • If the person is not regularly eating other foods that might be involved (tree nuts, legumes, sesame etc) then they should have tests done for these allergens as well. Specialised blood tests for parts of the peanut protein (called Arah2) are also available and indicate the allergy is more likely to be severe and less likely to go away.
  • Allergy tests can help us tell whether a person is allergic, but do not predict whether a reaction will be mild or severe. It is also important to know that not all people with a positive skin or blood test to peanut are actually allergic.


  • If you allergic to peanuts, you must avoid eating peanuts, peanut butter and products containing peanuts.
    It is important to read labels carefully on all packaged, processed foods, baked items, cereals and health foods.
  • Be especially careful at children’s parties and Oriental restaurants.
  • Children should take their own nut-free lunch to school and should not share and swap food.
  • The risk of children accidentally coming into contact in schools is high. Some schools have a nut free policy to help people with nut allergy avoid coming into contact with nuts on school grounds and at school events.
  • Some labels don’t actually say the food has nuts in it, but say the food “may contain traces of nuts” to indicate the possibility of cross contamination with nuts during the manufacturing process. People with severe allergies or reactions to trace amounts of nuts should avoid foods labelled in this way.

Emergency Treatment

  • Peanuts and tree nuts are very difficult to avoid completely, and most nut allergic people will have an accidental reaction every few years. Younger children may have more reactions from cross contamination as children share toys and foods.
  • Caregivers in schools, family members and friends should know about the allergy and what to do in an emergency. A detailed “action plan” should be provided in case of reactions. This should clearly describe the difference between mild and severe reactions as well as what to do if different types of reactions occur. The action plan should be highly visible at home and in the school/work environment.
  • The patient should have access to their emergency treatment at all times. For milder reactions an anti-histamine may be enough. For severe reactions, injectable adrenaline will be needed.
  • The allergy doctor should decide on whether a person with allergy is at risk to have a severe reaction. People with previous severe reactions or at risk of severe reactions should carry injectable adrenaline with them at all time, preferably in the form of an auto-injector.
  • People who have been prescribed an autoinjector must be trained when and how to use it and carry it with him/her at all times.
  • Peanut allergic individuals should wear a Medic alert or similar bracelet, especially if they have a severe allergy or also have asthma.

Experimental Treatments

Studies are currently looking into new treatments such as “oral desensitization” with peanut. Unfortunately these treatments are still only used in research and are not for management of allergies.

  • Peanut butter, mixed nuts, peanut oil *
  • Baked goods, biscuits, crackers, pastries
  • Cereals, muesli
  • Asian dishes, Indonesian dishes, Thai dishes, vegetarian dishes
  • Pesto
  • Health bars
  • Chocolates, sweets, nougat, marzipan
  • Vegetable fats and oils, hydrolysed vegetable protein, “natural “additives
  • Worcestershire sauce
  • Cosmetics/creams containing nut oils or arachis oil

*Highly refined peanut oil contains little peanut protein and has been shown to be safe in certain studies.

  • About 20% of children with peanut or tree nut allergy outgrow their allergy; 20% get worse and 60% stay much the same. If the allergy persists into teenage life, it is very unlikely to disappear.
  • Some people with peanut allergy will develop a new allergy over time to similar or related food. While many people with peanut or tree nut allergy are advised to avoid all nuts, it is not clear whether this will actually prevent a new allergy from developing.
  • Many allergists try to find out exactly which nuts the person is allergic to. If a person can tolerate certain kinds of nuts they are encouraged to continue eating them (in their pure form) so that they do not “develop” an allergy to that nut over time.
  • Children with nut allergy should see their allergy doctor regularly to check their growth and nutrition and to make sure they are managing to avoid the food and are able to treat any accidents correctly.
  • The allergy doctor will monitor the allergy one to two yearly either by skin prick or blood test. If those tests indicate that the allergy may have been outgrown then you (or your child) may be brought into hospital or clinic as a day case for a peanut challenge.
  • A peanut challenge is a supervised procedure where increasing doses of peanut protein will be fed to the patient to decide if tolerance has developed and if that the person is no longer allergic to peanuts (see oral food challenges).
  • Until a few years ago, pregnant and breastfeeding women were advised to avoid nuts to try to reduce allergies in their children. This has not been shown to work so avoiding nuts during pregnancy and breastfeeding is no longer recommended.
  • Several studies are currently underway looking at the best time to introduce “high allergy” foods such as peanut and egg to a weaning baby. New evidence suggests introduction of peanuts any time after 5 months of age may help reduce the risk of developing peanut allergy, especially in children with severe eczema and / or egg allergy.

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