Allergies Archive

Research we're watching

A bite from a lone star tick can trigger an unusual allergy that causes hives, swelling of the throat and lips, or an upset stomach when you eat red meat. But that's not all: people with this rare red meat allergy may be particularly prone to narrowed, stiff arteries in the heart, a new study finds.

Researchers analyzed blood samples from 118 adults living in Virginia and found that 26% had evidence of a red meat allergy (that is, they had antibodies to a molecule called alpha-gal, the main allergen in red meat). Lone star tick saliva may contain alpha-gal, so when a tick bites a person, it may trigger an immune response by the body, which then recurs when the body encounters alpha-gal in red meat. Lone star ticks are found throughout the southeastern and eastern United States.

Ask the doctors

Q. I'm very allergic to poison ivy. My spouse currently has a bad poison ivy rash that he got while trimming some bushes in our yard. I'm afraid I'm going to get a rash from him. Is it contagious?

A. Good news: poison ivy rashes are not contagious. You will get a rash from poison ivy only if you come into contact with urushiol oil, which is the plant oil in poison ivy that triggers the rash. In addition, a poison ivy rash, even one with open blisters, won't spread to other areas of the body. The rash only occurs on parts of the body that were actually exposed to the plant oil. Poison ivy rashes can appear to spread if urushiol oil is trapped under your fingernails and you scratch an itch. While you can't get a rash from coming from your spouse, you can get it from clothing or other items that have the plant oil on them. For example, the clothes your spouse was wearing that came into contact with the poison ivy plant. Poison ivy oil can cling to garden tools or even pet fur. The oil from poison ivy is known to linger. According to the FDA, it can stick around on surfaces, sometimes for years, until it is washed away using water or rubbing alcohol. So be certain that all surfaces that are potentially contaminated are cleaned thoroughly to reduce your risk.

What to do about prickly heat, poison ivy, and other uncomfortable skin reactions.

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Sunburn is a big risk in the summer. You know the rules: seek the shade, wear protective clothing, and use a broad-spectrum sunscreen (with an SPF of at least 30). But sunburn isn't the only summer skin problem.

Plant-related rashes

Many people are allergic to urushiol, an oil found in poison ivy and poison oak. Exposure occurs when you touch the plant directly, maybe while gardening, or indirectly, by touching an object that's picked up the oil (like a shoe). You can spread the oil wherever you touch your body until the oil is washed off. Two to 10 days later, the affected skin develops a red, itchy, blistering, oozing rash. It's not contagious, though you may feel like it's spreading. "The allergic reaction continues to unfold even after you've washed off the oil," says Dr. Jason Frangos, a dermatologist at Harvard-affiliated Brigham and Women's Hospital.

The overuse of antibiotics and antacids can lead to problems regardless of age, but if given to babies it can contribute to allergies and asthma as children grow.

Try stress reduction to improve your quality of life and potentially relieve allergy symptoms.

Spring allergies are a stressful business. Coping with watery eyes, a runny nose, sneezing, coughing, or a sore throat affects how you get through each day. "The primary consequence is a reduced quality of life. This naturally can lead to stress on patients and their families," says Dr. Ahmad Sedaghat, an ear, nose, and throat specialist at Harvard-affiliated Massachusetts Eye and Ear Infirmary.

The influence goes both ways: not only can allergies cause stress, but stress can make allergies worse.

Ask the doctors

Q. I feel like I have a perpetual cold all winter, every winter. I'm stuffy and sneezy and it never seems to get better. Do you think it could be allergies? How can I tell the difference?

A. Colds and allergies produce many of the same symptoms: a runny nose, tiredness, and sometimes a sore throat. But they have different causes — a virus causes colds, while allergies are an immune system response to trigger substances, known as allergens. There are ways to distinguish one from the other. Colds sometimes produce a fever, but allergies never do. In addition, if you are suffering from allergies, you may also have itchy, watery eyes, symptoms that won't typically accompany a cold. But perhaps the biggest clue that can help you distinguish between a cold and allergies is the duration of symptoms. Cold symptoms rarely last more than two weeks, but allergies can last as long as you are exposed to the substance that is triggering the reaction. So, if your "cold symptoms" appear at the same time every year and last for an extended period of time, the cause may very well be allergies. Many people with seasonal allergies will experience symptoms for six weeks at a time. If you are allergic to something in your home, such as dust mites, mold, or pet dander, your symptoms could get worse during the winter months, because the house is sealed up and fresh air isn't getting in. In addition, your heating system may be recirculating the allergen. Because your symptoms last for an extended period of time, it may be worth a visit to the allergist.

Reduce indoor allergens that can trigger respiratory problems and other issues.

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It may feel cozy being sealed in tight against the cold in your home during the chillier months of the year, but for people who are sensitive to indoor allergens or have respiratory problems, winter can exacerbate problems. Stale indoor air and heating systems can increase the amount of allergy-inducing dust mites, pet dander, and mold spores circulating through your house. In late winter and early spring, it may still be too chilly to throw open the windows to pull out the musty air, so while you await the warmer weather it's important to be aware of some of the allergy and respiratory triggers that may be lurking in your surroundings.

"Most of the things that cause problems are odorless," says Dr. Nicholas BuSaba, associate professor of otolaryng­ology at Harvard ­Medical School. "So, in many cases there's nothing to alert you to the problem." That is, there's nothing other than the symptoms these allergens can trigger — such as respiratory problems (including asthma flare-ups), fatigue and sleepiness, or even digestive issues.

Research we're watching

Some new research shows good reason to focus on reducing the number of indoor allergens in your home. A new study published in the Nov. 30, 2017, issue of The Journal of Allergy and Clinical Immunology found that more than 90% of nearly 7,000 homes studied had three or more detectable allergens, from a list of eight common allergens. In addition, some 73% of homes had one allergen found at levels researchers defined as "elevated." The researchers used data from the 2005–2006 National Health and Nutrition Examination Survey. The eight allergens were cat, dog, cockroach, mouse, rat, mold, and two types of dust mites. Factors that led to higher levels of indoor allergens included pets and pests. Certain types of homes were also more likely to have higher allergen levels, including older homes, rental homes, mobile homes, and homes in rural areas.

Research we're watching

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If you have an egg allergy, you may have been told not to get a flu shot. That's because the vaccine is grown in eggs and may contain a small amount of egg protein, which — it was feared — could trigger an allergic reaction. But a new guideline from the American College of Allergy, Asthma and Immunology (ACAAI) dispenses with that old advice and says even people with an egg allergy should roll up their sleeves and get the shot to protect themselves from the flu.

"When people get flu shots, health care providers often ask if they are allergic to eggs," allergist Dr. Matthew Greenhawt, chair of the ACAAI Food Allergy Committee and lead author of the practice parameter, said in a written release. "We want health care providers and people with egg allergy to know there is no need to ask this question anymore, and no need to take any special precautions. The overwhelming evidence since 2011 has shown that a flu shot poses no greater risk to those with egg allergy than those without." Numerous studies have found that patients with egg allergy — even those with life-threatening allergies to egg — have gotten the shot and did not suffer any ill effects. This suggests there isn't enough egg protein in the vaccine to cause a reaction.