By Michael Pistiner, MD

First it was the funny taste in his mouth. Then crankiness. Then vomiting. After about 20 minutes came throat clearing and some coughing. Thirty minutes later came the hives and itchiness. This was my son's reaction after he tried a chocolate walnut bar for the first time. He was 3 ½ at the time.

It's Asthma & Allergy Awareness Month and approximately 15 million Americans have a food allergy, including 6 million children, according to the Allergy & Asthma Network.

Each person can have different food allergy symptoms -- and even different symptoms from one reaction to the next. Symptoms can include itchiness and swelling on the lips or tongue, or an itchy, swollen rash on the skin. If symptoms worsen, there can be shortness of breath, coughing and wheezing, chest tightness, dizziness vomiting, and even loss of consciousness.

All because of a bite of food.

Most food-allergic reactions are mild, but there are approximately 30,000 episodes of food-induced anaphylaxis -- a severe, life-threatening, allergic reaction -- every year in the United States, including some that can be fatal.

The only proven way to prevent an allergic reaction is to avoid foods you or your child are allergic to -- that's why an accurate diagnosis from a board-certified allergist is essential. What's an allergen? An allergen is anything that causes an allergic reaction. People can be allergic to practically any food, but the most common food allergens in the United States are:

* Cow's milk * Eggs * Peanuts * Tree nuts (such as walnuts, almonds, or cashews) * Fish * Shellfish (such as crab, lobster, or shrimp) * Wheat * Soy

In addition to these Top 8 allergens, sesame allergy is on the rise in the United States. Less-common food allergens include corn, garlic, mustard, sunflower seeds, and poppy seeds.

Since allergens can be found in foods you don't normally expect, it's important for parents to read food product labels and avoid cross contact.

Federal law mandates that food labels list any allergens in clear language, either in the ingredients or in a "Contains" statement placement immediately after or next to the ingredients listing. Avoid food products labeled with advisory statement such as "May contain..." -- this means there's a chance the food allergen is present or it was made with equipment or utensils used on other food products containing allergens. Also, be cautious with imported foods as labeling regulations vary by country.

Cross-contact occurs when a food allergen comes into contact with a food that's safe for you. It happens more often than you think: dipping a knife in the jelly jar after using it to spread peanut butter, for example, or chopping almonds on a cutting board and then slicing a tomato without cleaning the cutting board first. Parents should thoroughly wash dishes, utensils, pots and pans, cutting boards, and countertops with hot, soapy water after preparing foods. What is the treatment for a severe or life-threatening allergic reaction? For all the allergen-avoidance strategies, accidental exposures still happen. When they do, and anaphylaxis strikes, epinephrine is the only drug that will treat symptoms. It should be given as soon as a severe reaction is suspected.

Epinephrine is a form of adrenaline, a hormone your body produces naturally in response to stressful situations. Administered through the use of an epinephrine auto-injector, the medication has a similar effect on the body. It increases your heart rate and blood pressure, relaxes muscles in the airways and suppresses your immune system's response to the allergens, halting the life-threatening effects.

Delays in administering epinephrine can increase the risk of hospitalization. Fatal reactions are often associated with delaying the use of epinephrine or not using it at all.

When you are prepared to treat an allergic reaction, it makes a real emergency situation less stressful.

Learn to recognize your child's signs and symptoms of an allergic reaction so you can give epinephrine as early as possible. Most allergic reactions happen within minutes to a few hours after contact with an allergen. Reactions can differ each time; they can start as mild symptoms and worsen quickly.

Talk to your child's doctor about when and how to use an epinephrine auto-injector. Each brand has a website with instructions and videos to help you learn how to use the device. Practice with a training device; studies show supervised epinephrine tutorials improve patient and parent comfort levels with administering the medication.

Be sure to ask your doctor to fill out an Allergy and Anaphylaxis Emergency Plan. The American Academy of Pediatrics developed the Allergy and Anaphylaxis Emergency Plan to spell out when to administer your epinephrine auto-injector. Read more about the plan and download a PDF version here.

If you're at risk for anaphylaxis, always carry two doses of epinephrine with you at all times. About 20% of children experiencing a food-induced anaphylactic reaction will experience a second reaction, called a biphasic reaction.

While antihistamines may be effective for mild allergic reactions, they do not treat severe or life-threatening reactions. And when allergic reactions occur, there's no way of knowing whether it will progress from mild to severe.

Clinical practice guidelines support epinephrine as the first line of defense to treat anaphylaxis.

After you give epinephrine, call 911 for an ambulance and request one that carries a supply of epinephrine so treatment is readily available in case a second reaction occurs.

Share as many details as possible about the incident and what may have caused the allergic reaction. Provide information about when the epinephrine auto-injector was administered; bring the used device if possible. After treatment, request a referral to a board-certified allergist if you don't already see one.

Michael Pistiner, MD, MMSc, is a Boston-based pediatric allergist with the Allergy & Asthma Network. He will join MassGeneral Hospital for Children's Food Allergy Center this summer. He is co-author of Living Confidently With Food Allergy and is a voluntary consultant with the Massachusetts Department of Public Health, School Health Service Unit.