Throat scratchy? Stomach upset? If you're one of the more than 3 million Americans living with a peanut allergy, it could be something you ate. Peanuts are among the most common allergy-causing foods, and they often find their way into things you wouldn't imagine. Like that chili you had for lunch? It may have been thickened with ground peanuts.

But peanuts ? which actually aren't a true nut, but a legume (in the same family as peas and lentils) ? aren't the only nuts that can send you into a wheezing fit. People can also be allergic to tree nuts, such as almonds, walnuts, pecans, cashews ? and even sunflower and sesame seeds.

What Happens When a Person Has a Nut or Peanut Allergy?

An allergic reaction happens when a person?s immune system mistakenly believes that a harmless substance, such as a nut or peanut, is actually harmful to the body. The immune system responds by creating specific antibodies to that food, which are designed to fight off the ?invader.? These antibodies ? called immunoglobulin E (IgE) ? trigger the release of certain chemicals into the body, one of which is histamine (pronounced: hiss-tuh-meen).

So when a person with a nut or peanut allergy eats a nut, peanut, or a food that contains nuts or peanuts, the immune system unleashes an army of chemicals to protect the body. The release of these chemicals can affect the respiratory system, gastrointestinal tract, skin, and the cardiovascular system ? causing allergy symptoms like wheezing, nausea, headache, stomachache, and itchy hives.

People with nut and peanut allergies could have a mild reaction - or it could be more severe. People also react differently in terms of how quickly they may have symptoms of an allergy. A reaction to a particular food could take place immediately, or a person may not feel anything until a few hours after eating it. Most reactions last less than a day and may affect any of three body systems:

* the skin ? in the form of red, bumpy rashes (hives), eczema, or redness and swelling around the mouth
* the gastrointestinal tract ? in the form of belly cramps, diarrhea, nausea, or vomiting

People have different allergic reactions to nuts and peanuts. Some people may not even recognize an allergic reaction In fact, people sometimes confuse an allergy with a cold, especially if it?s the first time it happens.

Although some people outgrow certain food allergies (like milk or egg allergy) over time, this doesn?t usually happen in people who have nut and peanut allergies. But the good news is that, over time, people with nut and peanut allergies usually become really good at avoiding the foods that make them sick.

How Is It Treated?

The only real way to treat a nut or peanut allergy is to avoid nuts and peanuts. That means more than just not eating the nuts themselves, though. Avoiding nuts also means not even touching them or being around people who are eating them. It also means not eating any foods that may contain nuts or peanuts as ingredients ? such as chili or chocolate chip cookies ? without first checking whether these foods have nuts. In some cases, miniscule amounts of nuts and peanuts can find their way into foods that shouldn?t contain them. This may be the case if a food product is made in a place that puts nuts in other foods. For more information, see the section below on Living With a Nut or Peanut Allergy.

If you've been diagnosed with a nut or peanut allergy, learn everything you can about what to watch out for and the type of reaction you'll have if you come into contact with nuts or peanuts.

If you have a severe nut or peanut allergy ? or any kind of serious allergy ? your doctor may want you to carry a shot of epinephrine (pronounced: eh-puh-neh-frin) with you in case of an emergency. Epinephrine comes in an easy-to-carry container about the size of a large marker. It?s easy to use ? your doctor will show you how.

If you accidentally eat something with nuts in it and start having serious allergic symptoms, like swelling inside your mouth, chest pain, or difficulty breathing, you can give yourself the shot right away to counteract the reaction while you're waiting for medical help. Always call for emergency help (911) when using epinephrine. You should make sure your school and even good friends' houses have injectable epinephrine on hand, too.

Keeping epinephrine on hand at all times should be just part of your action plan for living with a nut or peanut allergy. It's also a good idea to carry an over-the-counter antihistamine as this can help alleviate allergy symptoms in some people. Antihistamines should be used in addition to the epinephrine and not as a replacement for the shot.

If you've had to take an epinephrine shot because of an allergic reaction, then you should go immediately to a medical facility or hospital emergency room so they can give you additional treatment if you need it. Up to one third of anaphylactic reactions can have a second wave of symptoms several hours following the initial attack. Therefore, you might need to be observed in a clinic or hospital for 4 to 8 hours following the reaction.

Living With a Nut or Peanut Allergy

There's no cure for food allergies. The only way to stay healthy and avoid reactions is to stay away from nuts and peanuts. Foods like peanut butter or mixed nuts are obvious, but avoiding nuts isn't always that easy. Nuts are used in many foods, including some you'd least expect, like chili, gravy, and even ice cream!

You?ll need to avoid any food you're not sure about, such as baked goods, desserts, or other products that you didn't prepare yourself or for which you don't know the ingredients. It's also possible that a food that doesn't contain nut ingredients may have come into contact with nuts or peanuts if it's produced in a factory that also processes these ingredients (this is called cross contamination). Some factories may use the same equipment for nuts or peanuts as they do for products that don't contain them, so tiny amounts of nuts or peanuts could be transferred to other foods.

This is one reason why doctors advise peanut-allergic patients to avoid chocolate candies unless they're absolutely certain there's no risk of cross contamination during manufacturing. As more and more people become aware of allergy issues, though, many candy companies are making sure they make candies that contain nuts separately from those that don't have nuts or nut ingredients in them. That way, people with nut allergies can still enjoy their products. To be sure a candy is nut and peanut free, log on to the manufacturer's website or call the toll-free number listed on the package. Most companies have customer service representatives that can answer nut and peanut allergy questions accurately.

The best way to be sure a food is nut free is to read the label. As of January 2006, manufacturers of foods sold in the United States have to list on their labels whether a food contains ? or may contain ? any of the most common allergens. You should be able to find statements like these somewhere on the label: ?contains nuts,? or ?made in a facility that also processes nuts.?

If you've been diagnosed with a nut or peanut allergy, you'll need to tell your friends, family, and acquaintances. This helps if you're eating at someone else's home or in a restaurant, where your friends or family can alert you to foods that may contain nuts or peanuts.

In restaurants, tell servers that you have a nut allergy and ask if a food has been prepared with (or prepared near) nuts and peanuts. If they don't know, they can ask the kitchen staff to be sure. If you aren't sure, don't eat it. African, Chinese, Indonesian, Mexican, Thai, and Vietnamese dishes often contain peanuts, or they may be prepared in a kitchen where the foods come into contact with nuts or peanuts.

Here are some other tips that can make life a little easier for people who have an allergy to peanuts or nuts:

* Avoid eating from self-serve or other buffets where people may put spoons in and out of different bowls, risking cross contamination.
* Make your own snacks and lunches to take to other people's houses, parties, school, and on field trips so you have some safe food.
* Be sure everyone at school ? from the principal and staff to your friends and classmates ? knows about your food allergy. Ask for a nut-free table in the lunchroom if your school doesn't already have one.
* Encourage friends and family to wash their hands with soap and water or use hand wipes after meals. Just rinsing hands with water alone or using an alcohol-based hand sanitizer will not remove all nut or peanut residue.
* Avoid fried foods (especially in restaurants and fast-food places) that may be made with peanut oil or may contain hidden peanuts or nuts.
* Consult with a dietitian to come up with safe but delicious meals and snacks.
* Carry a list of foods to watch out for in your backpack or bag.
* Teach close friends to recognize the signs of anaphylaxis and show them how to help you.

Does having a nut or peanut allergy mean you can't do all of the things you love or enjoy some great-tasting food? Of course not. You'll just need to take precautions, like carrying that epinephrine shot everywhere you go and being cautious about the foods you're eating. A little bit of prevention and preparation will go a long way in keeping you healthy and free from nut and peanut allergy symptoms.