What is a nut allergy?

A nut allergy is when eating a small amount of nuts triggers an allergic reaction. Very sensitive people can also have a reaction if they:

• are exposed to tiny traces of nuts in the air
• touch a nut

A severe reaction — anaphylaxis — can be life threatening.

You can be allergic to different types of nuts. The most common ones are:

• almonds
• Brazil nuts
• cashews
• hazelnuts
• macadamia nuts
• pecans
• pine nuts
• pistachios
• walnuts

Peanut allergy is also very common. However, peanuts are legumes and not nuts. This means that if you’re allergic to peanuts, you will not be automatically allergic to tree nuts.

What causes nut allergy?

A nut allergy develops when your body's immune system becomes over-sensitive to a protein in a nut. Being exposed to the nut causes an allergic reaction.

The proteins in some nuts are very similar. This means that you can be allergic to more than one nut type, such as pecans and walnuts or cashews and pistachios.

Food allergies are more common in people who have other allergies such as hay fever, asthma or eczema.

How common are nut allergies?

Australia has a high rate of peanut allergies. At one year of age, about 3 in 100 children are allergic to peanuts.

By comparison, tree nut allergies are much rarer. About 1 in 500 children have a reaction to tree nuts at 5 years of age.

About 1 in 10 children will grow out of their tree nut allergy.

What are the symptoms of nut allergy?

A mild reaction to nuts may cause the following symptoms:

• hives or welts
• swelling around your mouth
• vomiting, stomach pains or diarrhoea

Even if you usually only have a mild allergic reaction to nuts, you are still at risk of having anaphylaxis.

Symptoms of anaphylaxis are:

• difficult or noisy breathing
• swollen tongue
• swollen, tight throat
• difficulty talking or a hoarse voice
• wheezing or persistent coughing
• dizziness
• collapse

Young children can become pale and floppy.

Anaphylaxis is potentially life threatening and needs emergency medical treatment.

How is nut allergy diagnosed?

If you have reacted to eating nuts, the first step is to see your doctor. They will examine you and ask questions about what has happened.

They may send you to an allergy specialist for a skin-prick test or blood test. This will show what you are allergic to.

Your doctor may also test you for allergies to:

• cow’s milk
• eggs
• other nuts

How is nut allergy treated?

Once you have a confirmed nut allergy, your doctor will prepare an allergy action plan. The action plan will be:

• red if you need an adrenaline autoinjector (brand names EpiPen or Anapen)
• green if you don’t need an adrenaline autoinjector

Your action plan tells you what to do if you are exposed to nuts.

There is no cure for nut allergy.

The best treatment for a nut allergy is to completely avoid exposure to the nuts you are allergic to.

Immunotherapy

In some people, it is possible to ease your allergy symptoms by being exposed to tiny quantities of allergen. The amount of allergen is gradually increased over time. This is called desensitisation therapy or allergen-specific immunotherapy.

This type of treatment is often used to treat other allergies (for example, such as pollen). It is not widely used in food and nut allergy. Research looking at desensitisation therapy in food and nut allergy is showing promising results — especially for peanut allergy.

Desensitisation therapy should only be done under the close supervision of a medical specialist.

Living with a nut allergy

If you are allergic to nuts, you must avoid any exposure to them. This can be very hard.

It’s important to recognise the nuts that you are allergic to and know which foods contain them.

It’s important to:

• Always carry your adrenaline autoinjector (EpiPen or Anapen) with you.
• Tell others about your allergy and what to do if you are exposed to nuts.
• Be careful when kissing or hugging someone — traces of nuts can stay on the hands, lips, teeth, beards and moustaches.
• Always carry a supply of safe food with you when travelling.

When buying cosmetics, you should also check that these don’t contain tree nut products.

Other possible sources of allergen can be:

• medicines
• alternative therapies
• pet food — such as bird seed

Eating at home

When eating at home you should always read food labels — nuts can easily be hidden. In Australia, common allergens must be listed on the food label.

Take care with knives and forks, kitchen surfaces, barbecue plates, and shared butter and margarine that might be contaminated.

Be careful when eating other nut products — even if you do not think you are allergic to them. You are at increased risk of developing an allergy to a new nut.

Eating out

Take extra care when eating out. Nuts are often used in:

• Asian food
• pesto
• hummus
• salad dressings

At restaurants, don’t rely on menu descriptions when ordering foods and drinks. Tell them about your allergy, and ask about ingredients, preparation and cross-contamination risks.

Children with nut allergies

Children should take their own food to school and parties.

Children should never share or swap food with other children.

Children with allergies may need to eat in a separate area from other children who are eating nuts.

Resources and support

You can read more about peanut, tree nut and seed allergy on the Australian Society of Clinical Immunology and Allergy (ASCIA) website. They also have fact sheets with tips on avoiding tree nuts and peanuts.

Allergy & Anaphylaxis Australia (A&AA) gives guidance and advice to Australians living with allergic disease. You can call them on 1300 728 000.

You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available to speak with 24 hours a day, 7 days a week.