Peanut allergies: What you need to know

What are peanut allergies?

Peanut allergy is an immune response to peanut proteins. There are 11 low molecular weight proteins in peanuts. Histamine and other chemicals are released when the body’s immune system produces IgE antibodies to these proteins. Very small amounts can cause a severe reaction.

Skin contact usually does not cause an allergic reaction or anaphylaxis. Local skin irritation (redness, hives) is possible.

Symptoms to know

Symptoms range in severity from skin rashes (hives, redness, swelling, itching), nausea, wheezing or trouble breathing, tingling of mouth and throat, throat tightness, swelling of lips, vomiting and low blood pressure.

When symptoms become life-threatening

The most severe reaction is anaphylaxis. Unlike milder allergic reactions, which affect only one body system like the skin, anaphylaxis usually affects at least two body systems. Typically, patients with anaphylaxis have very low blood pressure and may faint or collapse. Respiratory distress may develop from narrowed airways, with wheezing and throat swelling. Anaphylaxis is life-threatening and needs immediate treatment.

Diagnosis and treatment

Peanut allergies develop in childhood. They can be diagnosed using skin prick tests in which the skin is pricked after a small amount of peanut allergen is placed on the skin. If the person is allergic, a small bump will appear within 15-20 minutes. Another way to diagnose peanut allergy is to measure the blood for the peanut IgE antibody.

Avoiding peanuts is the best strategy for individuals with a peanut allergy. Epinephrine is the treatment for a severe allergic reaction or anaphylaxis, administered by an autoinjector such as an EpiPen. Adjunctive treatments include antihistamines, corticosteroids, and bronchodilators.

Omalizumab (brand name Xolair) reduces allergic reactions to several foods including peanuts. It binds to IgE antibodies, allowing some people to tolerate small amounts of peanut protein without a severe reaction. It lowers the risk of anaphylaxis so accidental ingestion will not be as severe. It is injected subcutaneously (under the skin) every 2-4 weeks. However, omalizumab is not a cure.

It is sometimes possible to treat the peanut allergy by oral immunotherapy. This involves eating small amounts and building up tolerance under the direct supervision of an allergist.

Can you outgrow a peanut allergy?

Peanut allergy is usually a lifelong allergy. It is uncommon for someone to outgrow a peanut allergy, but it is possible. Less than 20% of children outgrow peanut allergies.

Who is at the highest risk for peanut allergies?

Peanut allergies affect a relatively low percentage of people. Those at highest risk include babies and toddlers with a family history of allergies including peanut allergies, severe atopic dermatitis (eczema), and egg allergies. People with asthma are also at higher risk.  

Can peanut allergies be prevented?

Peanut allergies can be prevented. Introducing peanuts at an early age can decrease the chance of developing a peanut allergy. Experts recommend introducing peanut-containing foods at 4–6 months of age and continuing them regularly, about 2–3 times per week. Babies can be given smooth peanut butter, which has been mixed with water or pureed.

Are peanut allergies becoming more common?

Peanut allergies increased in the 1990s to early 2000s, affecting 0.4% of children in 1997 and 1.4-3% a decade later. This has since been attributed to the misguided recommendation to wait to introduce peanuts until age 3.

In 2008, a study comparing peanut allergy rates among Jewish children in Israel and the UK found that children in the UK had a 10-fold higher prevalence of peanut allergies than Israeli children. The difference was attributed to the fact that Israeli infants eat high quantities of peanut-flavored foods in the first year of life, whereas UK infants avoid peanuts.

In 2015, a randomized clinical trial known as the LEAP (Learning Early About Peanut) allergy study assigned 530 infants ages 4–11 months who were at high risk because of eczema or egg allergy to either consume peanut protein or avoid peanuts. At 5 years, the prevalence of peanut allergy in the early introduction group was 1.9% compared to 13.7 % in the group that avoided peanuts. The conclusion was that introducing peanuts early in life significantly reduced the frequency of peanut allergies in children at high risk for peanut allergy.

When and how to introduce peanuts to your baby

It is recommended that you introduce peanut products at ages 4-6 months.  Babies should not be given peanuts since they are a choking hazard, but can be given smooth peanut butter or Bamba (a peanut butter-flavored puffed-corn snack).

Living with peanut allergies

Those with peanut allergies should avoid peanut products, unless on a physician-guided plan to develop tolerance through increasing exposure. It’s not always obvious that peanuts are an ingredient of a food. Peanuts may be found in some candies, baked goods, cereals (granola, muesli), snacks (chips, crackers), sauces, dressings and marinades. Cold-pressed or expelled peanut oil may contain peanut proteins. Read ingredients on food products.

Be aware of synonyms for peanut proteins such as ground nuts, beer nuts, monkey nuts, earth nuts, arachis oil, and hydrolyzed plant protein. Use peanut alternatives such as pumpkin seeds or roasted chickpeas. Avoid food with warnings such as, “Processed in a facility with peanuts.” In shared kitchens, use separate cooking supplies. Carry an EpiPen. Make sure your family, friends, school staff, and co-workers know what to look for and when to use the epinephrine autoinjector.

What to do if someone is having an allergic reaction to a peanut product

If someone is having a severe allergic reaction to peanuts, use an autoinjector right away to give epinephrine. If an autoinjector is not available, seek medical attention immediately. Call 911.

For minor reactions, like a few hives, in a person who has never had a severe allergic reaction, you can start with an oral antihistamine to reduce hives and itching and monitor for worsening of symptoms which will necessitate administration of an epinephrine autoinjector.

While non-sedating antihistamines like Zyrtec (cetirizine) or Claritin (loratadine) are preferred, it’s ok to use a sedating antihistamine like Benadryl (diphenhydramine) if that’s available. If you are unsure whether an autoinjector is required, always err on the side of using it. Oral antihistamines alone will not prevent or treat anaphylaxis.

If you have a question about peanut allergies or using the epinephrine auto injector safely, use the webPOISONCONTROL^® online tool to get help, or call your poison center at 1-800-222-1222. Whether online or by phone, expert guidance is always free, confidential, and available 24 hours a day.