What is a tree nut allergy?

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

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

Anaphylaxis (a severe reaction) can be life-threatening.

You might be allergic to only one type of tree nut, or several.

Some common tree nuts include:

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

Peanuts are also common allergens (substances that trigger an allergic reaction), but they are legumes and not nuts. If you are allergic to tree nuts, you will not necessarily also be allergic to peanuts.

What are the symptoms of a tree nut allergy?

A mild allergic reaction to tree nuts may cause symptoms such as:

• hives or welts
• swelling around your mouth
• vomiting, abdominal pain or diarrhoea

Even if your past reactions were mild, there is still a risk you will experience anaphylaxis (severe allergic reaction).

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 may become pale and floppy.

Anaphylaxis is potentially life threatening and needs emergency medical treatment.

What causes a tree nut allergy?

A tree nut allergy develops when your body's immune system becomes over-sensitive to a protein in nuts. Exposure to tree nuts, usually through eating them, causes an allergic reaction.

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

When should I see my doctor?

You should see your doctor if you:

• think you or your child have experienced symptoms of tree nut allergy
• have questions or concerns about introducing tree nuts into your baby's diet
• do not have an allergy action plan and have ever had symptoms of a food allergy

How is a tree nut allergy diagnosed?

If you think that you or your child have reacted after eating tree nuts, the first step is to see your doctor. They will examine you and ask questions about what happened.

They may refer you to an allergy specialist for a skin-prick or blood test. A positive allergy test result doesn't always mean that you have an allergy. Ask your doctor what your results mean in your situation.

How is a tree nut allergy treated?

Once you have a confirmed 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 tree nuts.

There is no cure for tree nut allergy. The best treatment is to avoid the nuts you're allergic to.

If you have a diagnosed allergy to one type of tree nut, you should ask your doctor if it's safe for you to eat other types of nuts.

Immunotherapy

In some people, it is possible to ease allergy symptoms with exposure to tiny amounts of an allergen. The amount of allergen is gradually increased over time. This is called desensitisation therapy or allergen immunotherapy.

This type of treatment is often used to treat other allergies (for example, pollen). It is not yet widely used for food allergies.

Desensitisation therapy should only happen with close supervision by a medical specialist because of the risk of anaphylaxis.

Living with a tree nut allergy

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

It's important to know which foods may contain the tree nuts you're allergic to, so you can avoid them. Here are some tips:

• Always carry your adrenaline autoinjector (EpiPen or Anapen), even if you don't expect to eat.
• Tell others about your allergy and what to do if you are exposed to tree nuts.
• Be careful when kissing or hugging— traces of nuts can stay on hands, lips, teeth, beards and moustaches.
• Carry a supply of safe food with you when travelling.
• Check that cosmetics you buy are free from nuts.

Other possible sources of allergen can be:

• medicines
• alternative therapies
• pet food

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 shared utensils, surfaces and foods that may be cross-contaminated.

Eating out

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

• African, Asian and Indian food
• salad dressings or salads
• cereals and muesli bars
• desserts

At restaurants, don't rely on menu descriptions. Tell staff about your allergy and ask about ingredients and cross-contamination.

Allergy and Anaphylaxis Australia has developed a tree nut allergen card and a chef card to bring with you when eating out. You can give it to the wait staff or chef when telling them about your allergy. It's also available in a variety of languages if you are travelling.

Children with allergies

Children should take their own food to school and parties.

Children should never share or swap food with other children.

Some children may need to eat away from others eating tree nuts. Take care not to exclude them socially, wherever possible.

What are the complications of a tree nut allergy?

If someone with a tree nut allergy is exposed to nuts, they may develop a serious allergic reaction (anaphylaxis) which may be life-threatening.

Can a tree nut allergy be prevented?

Tree nut allergy can't be completely prevented, but there are things you can do to reduce your child's chance of developing a food allergy:

• Introduce solid food between 4 and 6 months of age.
• Try to introduce common food allergens in an age-appropriate form (such as smooth nut butter or paste) before 12 months of age. This advice also applies to children who may have a higher chance of developing food allergy, such as those with severe eczema or egg allergy, or those with a family member who has a food allergy.
• Breastfeed for at least 6 months, if you can.
• Avoiding nuts while pregnant or breastfeeding will not prevent food allergies in your child.
• If your child has eczema, make sure it is well-controlled.
• Do not smoke during pregnancy or around your young child.

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.
• Nip Allergies in the Bub has information for parents about introducing common allergy foods to children.
• Call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available 24 hours a day, 7 days a week.

Do you prefer to read in languages other than English?

Nip Allergies in the Bub has resources about introducing common allergy foods to babies in a variety of community languages.