Allergies Archive

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.

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.

For decades, people with an allergy to dust mites took over-the-counter medications for relief, and if those were not effective they could choose to receive a course of immunotherapy shots that lasted years. A newer form of treatment is available in pill form and is taken at home.

Ask the doctors

Q. Is it true that I should skip my annual flu shot if I'm allergic to eggs? If not, is it too late in the season to get one?

A. In the past, people with egg allergies were advised not to get the flu vaccine, but that advice no longer holds true. Most flu vaccines contain small amounts of egg proteins, which are introduced during the vaccine-manufacturing process. However, the CDC now advises that even people with egg allergies should receive the flu vaccine, because the risk of a severe allergic reaction is so small — only an estimated 1.31 vaccinations in every million.

Even if you're isolating to avoid COVID-19, it's still important to be proactive when it comes to allergies.

This is normally the time of year to think about taking medications to ward off spring allergies. Starting treatment about a month before the season (which begins in February in some parts of the country) gives the drug time to achieve its full effect and prevent symptoms.

But the pandemic may have you questioning that approach: is an early regimen necessary if you're isolating and you're not going outside very often? The answer is yes. "Even a short walk around the neighborhood, sitting on a patio, or simply opening the windows for fresh air could expose you to allergens," says Dr. Anna Wolfson, an allergist and immunologist at Harvard-affiliated Massachusetts General Hospital.

The potential causes may be hard to pin down. Here are some of the most common ones — and what to do about them.

Sometimes it's easy to know why a particular part of your body is itchy. Maybe you have a bug bite, allergies, or a visible skin condition such as eczema. It's harder to know the cause when there's nothing obvious behind all-over, generalized itching. "It's the most common skin complaint in people over age 65," says Dr. Kenneth Arndt, a dermatologist and former medical editor of the Harvard Special Health Report Skin Care and Repair.

Potential causes

Generalized itching has many potential triggers. One is aging. "The skin barrier doesn't work as well as it used to, and things that may not have irritated you before may now be absorbed in the skin and cause itching," Dr. Arndt explains. "The skin also develops a somewhat impaired immune response, a reduction in fat and blood flow, and altered sensory perception, making it more prone to itching."

In the journals

Many commonly used drugs have anticholinergic effects, meaning the drugs block the action of acetylcholine. Nerve cells release acetylcholine to transmit impulses to other nerves in the brain and throughout the body. Previous research has shown a link between these drugs and dementia. Now a study has found a similar link with mild cognitive impairment (MCI), especially if you take larger doses. The findings were published online Sept. 2, 2020, by Neurology.

Some medications are designed purposefully to block acetylcholine, such as those used for urinary incontinence. But more often the anticholinergic action is a side effect of drugs taken to treat conditions like allergies, colds, and depression.

On call

Q. What would cause my tongue to suddenly swell? Could this be a possible side effect of medication, or something else?

A. There are many reasons for a swollen tongue. Indeed, a reaction to a medication is one of the more common causes. For example, a well-known side effect of ACE inhibitors (a class of drugs used to control blood pressure) is a condition called angioneurotic edema. Swelling of the face, lips, and tongue can happen quickly in people who take an ACE inhibitor. The reaction may occur soon after it's first taken or at any time thereafter. Sometimes people get this reaction even though they have used the drug for several years. ACE inhibitors are more likely to cause angioneurotic edema in African Americans.

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.