Nut and Peanut Allergy

What Are Peanut and Tree Nut Allergies?

Peanuts are among the most common allergy-causing foods, and they often find their way into things you wouldn't expect. Take chili, for example: It may be thickened with ground peanuts.

Peanuts aren't actually a true nut; they're a legume (in the same family as peas and lentils). But the proteins in peanuts are similar in structure to those in tree nuts. For this reason, people who are allergic to peanuts can also be allergic to tree nuts, such as almonds, Brazil nuts, walnuts, hazelnuts, macadamia nuts, pistachios, pecans, and cashews.

Sometimes people outgrow some food allergies over time (like milk, egg, soy, and wheat allergies), but peanut and tree nut allergies are lifelong in many people.

What Happens With a Tree Nut or Peanut Allergy?

When someone has a nut allergy, the body's immune system, which normally fights infections, overreacts to proteins in the nut. If the person eats something that contains the nut, the body thinks these proteins are harmful invaders and responds by working very hard to fight off the invader. This causes an allergic reaction.

Even a small amount of peanut or tree nut protein can set off a reaction. But allergic reactions from breathing in small particles of nuts or peanuts are rare. That's because the food usually needs to be eaten to cause a reaction. Most foods with peanuts in them don't allow enough of the protein to escape into the air to cause a reaction. And just the smell of foods containing peanuts won't cause one because the scent doesn't contain the protein.

What Are the Signs & Symptoms of a Nut Allergy?

When someone with a peanut or tree nut allergy has something with nuts in it, the body releases chemicals like histamine .

This can cause symptoms such as:

• wheezing
• trouble breathing
• coughing
• sneezing
• hoarseness
• throat tightness
• stomachache
• vomiting
• diarrhea
• itchy, watery, or swollen eyes
• hives
• swelling
• a drop in blood pressure
• dizziness or fainting
• anxiety or a feeling something bad is happening

Reactions to foods, like peanuts and tree nuts, can be different. It all depends on the person — and sometimes the same person can react differently at different times.

How Is an Allergic Reaction Treated?

A nut allergy sometimes can cause a severe reaction called anaphylaxis. Anaphylaxis might start with some of the same symptoms as a less severe reaction, but can quickly get worse. The person may have trouble breathing or pass out. More than one part of the body might be involved. If it isn't treated, anaphylaxis can be life-threatening.

If your child has a peanut or tree nut allergy (or any kind of serious food allergy), the doctor will want him or her to carry an epinephrine auto-injector in case of an emergency.

An epinephrine auto-injector is a prescription medicine that comes in a small, easy-to-carry container. It's easy to use. Your doctor will show you how. Kids who are old enough can be taught how to give themselves the injection. If they carry the epinephrine, it should be nearby, not left in a locker or in the nurse's office.

Wherever your child is, caregivers should always know where the epinephrine is, have easy access to it, and know how to give the shot. Staff at your child's school should know about the allergy and have an action plan in place. Your child's medicines should be accessible at all times.

Every second counts in an allergic reaction. If your child starts having serious allergic symptoms, like swelling of the mouth or throat or difficulty breathing, give the epinephrine auto-injector right away. Also give it right away if the symptoms involve two different parts of the body, like hives with vomiting. Then call 911 and take your child to the emergency room. Your child needs to be under medical supervision because even if the worst seems to have passed, a second wave of serious symptoms can happen.

Living With Peanut or Tree Nut Allergy

If allergy skin testing shows that your child has a peanut or tree nut allergy, an allergist will provide guidelines on what to do.

The best way to prevent a reaction is to avoid peanuts and tree nuts. Avoiding these nuts means more than just not eating them. It also means not eating any foods that might contain tree nuts or peanuts as ingredients.

The best way to be sure a food is nut-free is to read the food label. Manufacturers of foods sold in the United States must state on their labels whether the foods contain peanuts or tree nuts. Check the ingredients list first.

After checking the ingredients list, look on the label for phrases like these:

• "may contain tree nuts"
• "produced on shared equipment with tree nuts or peanuts"

Although these foods might not use nut ingredients, the warnings are there to let people know they might contain traces of nuts. That can happen through "cross-contamination," when nuts get into a food product because it is made or served in a place that uses nuts in other foods. Manufacturers are not required to list peanuts or tree nuts on the label when there might be accidental cross-contamination, but many do.

Some of the highest-risk foods for people with peanut or tree nut allergy include:

• Cookies and baked goods. Even if baked goods don't contain nut ingredients, they might have come in contact with peanut or tree nuts through cross-contamination. Unless you know exactly what went into a food and where it was made, it's safest to avoid store-bought or bakery cookies and other baked goods.
• Candy. Candies made by small bakeries or manufacturers (or homemade candies) may contain nuts as a hidden ingredient. The safest plan is to eat only candies made by major manufacturers whose labels show they are safe.
• Ice cream. Unfortunately, cross-contamination is common in ice cream parlors because of shared scoops. It's also a possibility in soft-serve ice cream, custard, water ice, and yogurt shops because the same dispensing machines and utensils are often used for lots of different flavors. Instead, do as you would for candy: Buy tubs of ice cream at the supermarket and be sure they're made by a large manufacturer and the labels indicate they're safe.
• Asian, African, and other cuisine. African and Asian (especially Thai, Chinese, and Indian) foods often contain peanuts or tree nuts. Mexican and Mediterranean foods may also use nuts, so the risk of cross-contamination is high with these foods.
• Sauces. Many cooks use peanuts or peanut butter to thicken chili and other sauces.

Always be cautious. Even if your child has eaten a food in the past, manufacturers sometimes change their processes — for example, switching suppliers to a company that uses shared equipment with nuts. And two foods that seem the same might have differences in their manufacturing. Because ingredients can change, it's important to read the label every time, even if the food was safe in the past.

What Else Should I Know?

To help reduce contact with nut allergens and the possibility of reactions in someone with a peanut or tree nut allergy:

• If you keep peanuts and nuts in your home, watch for cross-contamination that can happen with utensils and cookware. For example, make sure the knife you use to make peanut butter sandwiches is not used in preparing food for a child with a nut allergy, and that nut breads are not toasted in the same toaster as other breads.
• Don't serve cooked foods you didn't make yourself, or anything with an unknown list of ingredients.
• Tell everyone who handles the food your child eats, from waiters and waitresses to the cafeteria staff at school, about the allergy. If the manager or owner of a restaurant is uncomfortable about your request for peanut- or nut-free food preparation, don't eat there.
• Consider making your child's school lunches, as well as snacks and treats to take to parties, play dates, sleepovers, school events, and other outings.
• Work with the childcare supervisor or school principal to make sure the food allergy emergency action plan provided by your allergist is followed correctly.
• Keep epinephrine accessible at all times — not in the glove compartment of your car, but with you. Seconds count during an anaphylaxis episode.

A little preparation and prevention can help make sure that your child's allergy doesn't get in the way of a happy, healthy everyday life.