As a feature of CNNhealth.com, our team of expert doctors will answer readers' questions. Here's a question for Dr. Gupta.

From Kali in Florida:

My 4-year-old daughter has egg and peanut allergies. Can she still take the H1N1 vaccine? If not what are her choices. I've been getting conflicting answers.

Answer:

Kali thanks for writing in. We’ve received several questions like yours since the H1N1 vaccine became available. Let me start by saying that if your daughter has a true egg allergy, and not just a sensitivity, then she can not have the H1N1 or the seasonal flu vaccine. The two types of H1N1 vaccine, the shot and the nasal spray, are made with eggs so it is not recommended for people with severe egg allergies.

However, allergists we spoke with said people with mild reactions to eggs can get vaccinated. Keep in mind that the amount of egg protein in a vaccine is often less than you would find in most baked goods. So if your daughter has been able to eat bread or cake, she may have a more mild allergy.

Consider going to an allergist and ask about getting a skin-prick test. The allergist will have a diluted and non-diluted version of the vaccine. Their first step will be to do the skin-prick test with the undiluted version. If your daughter does not break out in hives or have a strong reaction, then she can have a stronger test with a small, diluted injection. If your child doesn’t have a strong reaction to that test, then her allergy may not be severe and your allergist may give her a flu shot.

If your child does have a strong reaction and your doctor believes she shouldn’t get the flu shot, then talk with your health care provider about strategies for keeping her healthy. These steps are basic hygiene, such as washing hands for the count of singing the “Happy Birthday” song twice and staying away from sick friends plus, avoid wiping your eyes and touching your face if possible.

I hope this helps and your daughter has a flu-free season

By Ann J. Curley
CNN Medical Assignment Manager

Many of our readers are still asking questions about H1N1 and seasonal influenza. Today we’ve got a question from Patty:

I am a 63-year-old health care worker in relatively good health, and I’m caring for a 2-month-old infant (my granddaughter). I have had a reaction to thimerosal in the past. It was used as a preservative in contact lens solution.

Is thimerosal used as a preservative in either seasonal flu vaccine or H1N1 vaccine? Are there available alternatives to these vaccines? How would I access them?

Thanks,
Patty Holly

Patty,

Thank you for your question. It’s important that you make your health care provider aware of your sensitivity to thimerosal, which is a preservative used in many products, including some vaccines, nasal products, and eye solutions.

According to the Centers for Disease Control and Prevention, the 2009 H1N1 influenza vaccines approved by the FDA are being manufactured with and without thimerosal.

Multi-dose vials of flu vaccine need to contain a preservative to prevent bacterial contamination, which can occur when multiple syringes are inserted into the same bottle.  However, some manufacturers also produce single-dose flu shots, which do not require any preservatives.

The nasal flu vaccine – both for seasonal flu and H1N1 – is always thimerosal-free. However, it is recommended only for people ages 2 to 49 who have no underlying health problems. The nasal spray vaccine is made from a weakened live virus and is not recommended for people with autoimmune disorders, pregnant women, and patients with certain chronic health problems, including diabetes, heart disease, asthma, and lung disease. Unfortunately, you can’t take the nasal flu vaccine because you are 63. You can find more information about the live vaccine here.

Ask your doctor for a thimerosal-free flu shot. If he or she doesn’t have one, you can visit the CDC’s H1N1 Web site and check out its “flu shot locator” .  It has links to the Web site of each state’s health department, with specific information about where vaccine can be found.

The Centers for Disease Control and Prevention has a lot of useful information about both seasonal flu and H1N1 flu on its Web site. Also be sure to check out CNN.com’s flu page.

Editor's Note: Medical news is a popular but sensitive subject rooted in science. We receive many comments on this blog each day; not all are posted. Our hope is that much will be learned from the sharing of useful information and personal experiences based on the medical and health topics of the blog. We encourage you to focus your comments on those medical and health topics and we appreciate your input. Thank you for your participation.

By Elizabeth Landau
CNN.com Health Writer

Since allergy season began in late March, I have been trying to avoid settings where a lot of people are likely to be smoking. Even outside in Atlanta’s hipster neighborhood of Little Five Points, I found myself coughing uncontrollably last week when walking past a group of people smoking on a corner. Allergists agree that cigarette smoke aggravates allergies.

But a new study recommended by the Faculty of 1000 Biology challenges this conventional wisdom. Researchers at Utrecht University in the Netherlands took mast cells, which play a role in the immune response to allergies, from mice, and treated them with a smoke-infused solution.

They found that the smoke treatment prevented the mast cells from releasing inflammation-induced proteins, which is what normally happens when exposed to allergens. The smoke solution did not affect other mast cell immune functions, the researchers said. This anti-allergy effect would likely hold true for humans, they wrote.

The general idea that smoke would help allergies is surprising, said Dr. Stanley Fineman, allergist with the Atlanta Allergy and Asthma Clinic.

“In humans, we know from the patients that we see that cigarette smoke is very irritating to the mucosa, the lining of the airways,” he said. “People who have allergies tend to have inflamed respiratory mucosa.”

Years of patient work has shown that smoke is detrimental to people with allergies, he said.

Whatever benefits to allergies cigarette smoke may theoretically carry, the costs are hard to ignore: Cigarette smoking accounts for about 30 percent of all cancer deaths nationwide, according the American Cancer Society. About 87 percent of lung cancer deaths, the leading cause of cancer death among both men and women, are caused by smoking. Smoking can also lead to other types of cancer.

Editor's Note: Medical news is a popular but sensitive subject rooted in science. We receive many comments on this blog each day; not all are posted. Our hope is that much will be learned from the sharing of useful information and personal experiences based on the medical and health topics of the blog. We encourage you to focus your comments on those medical and health topics and we appreciate your input. Thank you for your participation.

By Miriam Falco
CNN Medical News Managing Editor

About 20 years ago, when I was barely out of college and a struggling journalist, I developed a horrible sore throat. I didn't have a regular doctor, so I had my throat examined in a small clinic in a strip mall. The doctor figured I had strep throat, but the test came back negative. Still, she prescribed antibiotics and sent me on my way. The next morning, I woke up with little red dots all over my body, so I went back to the clinic. The same doc looked at me, said I had hives, harrumpfed that I was allergic to penicillin and gave me a prescription for a different antibiotic. The sore throat eventually went away, but every time since that I've gone to a doctor or dentist and I’ve listed penicillin as one of my allergies. Still, I always wondered if I really had an allergy; I took penicillin frequently during my childhood and never had an allergic reaction.

I came across a recent study published in the Annals of Emergency Medicine that said 80 to 90 percent of people who report being allergic to penicillin are really not.

This new study sought to determine how many patients who came into an Emergency Department (ED) and said they are allergic to penicillin really were allergic. Using two back-to-back skin tests, doctors in the ED at the University of Cincinnati tested 150 patients who reported having a penicillin allergy. 91 percent of these patients tested negative for the allergy.

For Dr. Joseph Moellman, an associate professor at the University of Cincinnati Department of Emergency Medicine, who conducted this study, finding out that taking the additional 30 minutes to conduct these two tests has several important implications. "We see a lot of patients with pneumonia, with sepsis, for which penicillin is a great drug...It's also a lot cheaper." Moellman says the average cost saving is $71. So if, for example, a pneumonia patient is in the hospital for a week, and possibly needs antibiotics every six hours – significant savings can add up very quickly. Plus, using penicillin where it's known to work allows doctors to save the few newer antibiotics we have for illnesses that have become resistant to penicillin.

"This is good information," says Dr. Clifford Bassett, an allergy expert and spokesperson for the American Academy for Allergy, Asthma and Immunology. "The fact that the test is fast and inexpensive is helpful." But he did point out that there has been a shortage of proper testing agents for penicillin. Once these testing agents become more widely available again, Bassett says that this test could be done in other settings too, not just in an emergency room, but also in a regular doctor's practice.

He adds that some previous research suggests that some people who genuinely were allergic to penicillin could lose their allergy if they don't come in contact with this drug for 10 years or more.

Of course neither doctor could explain whether I really am allergic to penicillin. But Moellman explained that sometimes a virus itself can cause hives, and Bassett told me that usually it takes more than 24 hours for a penicillin allergy to become evident. I, for one, plan to get tested to determine whether I truly am allergic to penicillin.

Have you been told you're allergic to penicillin? Would you consider getting tested?

Editor's Note: Medical news is a popular but sensitive subject rooted in science. We receive many comments on this blog each day; not all are posted. Our hope is that much will be learned from the sharing of useful information and personal experiences based on the medical and health topics of the blog. We encourage you to focus your comments on those medical and health topics and we appreciate your input. Thank you for your participation.

By Elizabeth Landau
CNN.com Health Writer/Producer

“We’ve come up with a compromise,” the flight attendant told me.

I was on a flight from Amsterdam to Atlanta in October. I had almost made it back to America in perfect health after two weeks in Moscow. But now hundreds of people on this 747 were about to release toasted almond particles into the air at once, and unfortunately, I’m among the 3 million Americans who are allergic to peanuts and/or tree nuts. Some people may experience symptoms just from breathing the offending food, but there’s no way to predict how strongly any particular individual will react.

Maybe I’m paranoid but, given that I have endured near-fatal reactions from eating these foods, and a strong smell alone seems to prime my body for sickness, it’s hard to justify taking a chance. It’s especially worrisome on a long flight over the Atlantic Ocean.

Sure, I knew what I was getting into – I had thoroughly researched the airline’s peanut policy, but I hadn’t counted on other forms of nuts as the main snack. Still, when I flew out to Amsterdam, the cabin crew not only refrained from serving the nuts at my request, but also made an announcement that there was a passenger on board who has peanut and nut allergies, and could everyone please refrain from eating these products. I felt safe for the entire flight.

Coming back to America, on the other hand, the flight attendant in charge of my section questioned why I would be flying at all if I had such a problem. Even after I explained my previous experience, the person in charge made the decision that nuts would be served, no matter what.

The compromise was that I would spend a little over an hour in quarantine, sitting in a small curtained-off area at the very back of the cabin with the food and drink carts. I sat on a folding chair and played with my laptop, moving every few minutes so the flight attendants could squeeze by.

Making things even more confusing, some airlines’ policies seem to change every few years, and sometimes snacks vary according to the route. There are a few airlines, though, that seem to be consistently peanut-free these days, and they’re the ones that I use every time I travel within the U.S. Note that I’ve never been in a situation in the U.S. where people around me brought their own peanuts or even any other strong-smelling nut product to eat on a plane and, anecdotally, I question whether airplane passengers like eating peanuts that much.

So when I heard about Northwest reintroducing peanuts on board this month, I sighed – another airline to cross off my list. Would it really be so hard to just serve pretzels?

Do you have food allergies? What have you experienced when flying?

Editor's Note:  Medical news is a popular but sensitive subject rooted in science. We receive many comments on this blog each day; not all are posted. Our hope is that much will be learned from the sharing of useful information and personal experiences based on the medical and health topics of the blog. We encourage you to focus your comments on those medical and health topics and we appreciate your input. Thank you for your participation.

By Elizabeth Landau
CNN.com Health Writer/Producer

I was a junior at Princeton when a group of student journalists and I excitedly sat down for dinner with Los Angeles Times columnist Joel Stein at J.B. Winberie Restaurant about three or four years ago. Whenever I dine out with people I don’t know well, it’s always a little embarrassing to tell the server that I have severe allergies to all nuts and peanuts. It’s especially embarrassing when a writer I admire is a dinner guest – so I try to be as discreet as possible when inquiring about the ingredients that went into certain menu items. (Of course, it would be all the more embarrassing to actually incur a life-threatening reaction at the table).

Recently I was surprised to read a column expressing that, in Stein’s view, food allergies are on the rise because of “Yuppiedom.” His argument is that the increase in food allergies among children in the U.S. is best explained by paranoia-fueled mass hysteria. He writes that “peanut allergies are only an issue in rich, lefty communities” and that the parent of an allergic child is perhaps just “a parent who needs to feel special.” (Read the column)

Let me reiterate that I greatly admire Stein as a writer, and his columns are often funny in a good way. But this issue is not light-hearted. About 12 million Americans have food allergies, and the statistics are more concerning among children – one out of every 17 children under 3 years old in America has an allergy, according to the Food Allergy and Anaphylaxis Network (FAAN). Some of those 12 million, like me, have had near-fatal reactions to common foods, such as milk, eggs, fish, shellfish, peanuts, tree nuts, wheat and soy. Some of the children will grow out of their allergies but, experts say, many with seafood or nut problems need to avoid those foods for life. It’s true that we don’t know why allergies have been on the rise – experts say maybe Americans are overly hygienic, or that it’s genes, or environmental factors – but I’m pretty sure it’s not because of “Yuppiedom” that I had to go to the hospital a few years ago after eating the wrong cookie.

Perhaps most troubling, Mr. Stein suggests we probably don’t need explicit ingredient labels or to take peanuts out of schools because “food allergies kill about as many people as lightning strikes each year.” Even if the actual food allergy mortality rate is low – a number that would undoubtedly be hard to measure because the cause of death may be misdiagnosed – perhaps it’s related to all of the life-saving interventions that exist today, most notably the portable epinephrine injection sold as EpiPen. Without the prevalence of EpiPens and the conscientiousness of food companies, schools and restaurants, perhaps that death rate would be a lot higher.

Albeit perhaps unintentionally, Stein does make a good point about food labels. While there are not literally labels that say “made in a factory that also has a break room where a guy named Dave often sneaks in a King Size Snickers despite this 'diet' he says he's on,” parents do have to wonder whether that description is any more meaningful than “made in a factory that processes products with peanuts.” The truth is that we really don’t know what any of this means in terms of how safe those products are for children with peanut allergies. The Food and Drug Administration's held a public hearing in September on this very issue.

The bottom line is that, for those millions of Americans who have food allergies, well-informed awareness of the issue is critical. Perhaps there are parents out there who are unnecessarily paranoid about their children having allergies, but it wouldn’t have become an issue if there weren’t plenty of parents with legitimate, evidence-based concerns about their children who really could die from common foods.

For those of us who DO have allergies, please don’t throw peanuts back at us.

Editor's Note: Medical news is a popular but sensitive subject rooted in science. We receive many comments on this blog each day; not all are posted. Our hope is that much will be learned from the sharing of useful information and personal experiences based on the medical and health topics of the blog. We encourage you to focus your comments on those medical and health topics and we appreciate your input. Thank you for your participation.

As a new feature of CNNhealth.com, our team of expert doctors will answer readers' questions. Here's a question for Dr. Gupta.

Question asked by Jennifer, Ellijay, Georgia

"Our 17-month-old son was recently given peanut butter during snack time and he had a very severe allergic reaction. How common are peanut allergies, what causes them and what steps can we take to ensure we avoid peanuts?"
 
Answer:
 

Jennifer, food allergies are quite common among children. About 8 percent of kids have some sort of food allergies, the most common allergen being peanuts.   Peanut reactions can cause dizziness, constricted breathing and in some cases loss of consciousness.  What’s happening is your child’s immune system can’t process the protein found in peanuts.  As a defense mechanism, it identifies it as harmful and causes the reaction. 

To avoid trouble, you need to read food labels very carefully. If you are at a restaurant, be sure to alert the server of your peanut allergy.  There are often hidden sources of peanuts in certain foods. For example, arachis oil is actually peanut oil.  And it's common for sunflower seeds to be sorted on machines shared with peanuts.  Also, many ethnic foods, including Thai, African and Chinese dishes contain peanuts. 

 As your child gets older, inform him of the allergy and the risks. Discourage him from sharing foods with other children or at school, which will help limit any surprise attacks.  Also, inform all the key people in your child’s life about the allergy.  Never assume an aunt, a family friend, a baby sitter, or the day care or school knows about his allergy.

 Finally, be prepared: Carry and epinephrine shot on you at all times.  You can also leave a dose with the school or day care in case of emergency.  Epinephrine will increase blood pressure and the open airways in the lungs.

I know it seems like a lot to process but know you aren’t alone! There are many resources on the Web and as well as food allergy support groups to offer more tips to make the transition in diet easier.

By Val Willingham
CNN Medical Producer

When I was a little girl, my mother would get allergy shots. It was a big deal, because in my childlike mind, I could never understand why anyone would use a needle to get relief. But she was one of those people who was allergic to everything: pollen, ragweed, mold. She was miserable all year long. The shots helped her make it through the day. But as she got older, her allergies changed. She gave up the inoculations, took some over the counter medication and eventually weaned herself off the meds. The allergens just didn't seem to bother her anymore.

Fast forward 30 years. My mom is now 83 and guess what? Her allergies are back. They're not as bad as when she was in her thirties, but they effect her enough to alter her life. She avoids going out on high pollen days and keeps her windows closed; leaving the air conditioning on. She sneezes a lot and feels rundown from time to time. But she says they are still not as bad as when she was younger.

Doctors say the return of allergies as we get older is not unusual. Some people can have allergic reactions when they're young and then never have them again when they hit middle age. Some sufferers are like my mother, who go for years without symptoms and then, wham -they come back. Or others can go their whole lives without allergies and then in their forties and fifties start to sneeze and wheeze.

Allergists say there are a number of factors that cause this. Dr. Jordan Josephson, an otolaryngologist at Lenox Hill Hospital in New York City says, "Allergens are getting worse and worse. There are things called super antigens, which means that all the car exhaust and pollution that can link up with maybe mold and creating super antigens that people are more allergic to." Dr. Josephson even mentions that global warming may play a part. As the climate of our planet shifts and our weather patterns change, allergen strains tend to become more potent.

Physicians also warn that as you age, allergies can become more of a health problem. Watch out if you are grabbing an over the counter medication for relief. If you're taking prescription medicine for blood pressure or cholesterol, the OTC medication could cause some negative reactions. Dr. Josephson warns, "If you have heart problems any decongestants can adversely affect those heart problems. You have to be very, very careful and if you are a man and you are having a prostate problem, as men get older they tend to have that, antihistamines and decongestants can cause your prostate to act up and swell and can give you terrible urinary problems." Stay in touch with your doctor and make sure you're getting your allergies treated properly.

Are you an allergy sufferer? How have your allergies changed your life and what do you do to fight them? Let us know.