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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.

People who are allergic to penicillin are often given less effective medications that can make them more susceptible to infections, but many people who believe they are allergic to penicillin are not. New techniques are allowing medical providers to assess whether or not a person has a true penicillin allergy.

Many people have experienced mild allergic reactions to a food, medication, or other allergen, but a severe reaction can be harmful or even fatal. Anaphylaxis must be treated with epinephrine as quickly as possible, followed by a visit to a hospital emergency room for observation.

Many children look forward to warm, mild spring weather, but kids with seasonal allergies (also known as hay fever) might not. Hay fever can interfere with a child's ability to play outdoors, and it can just plain make them feel miserable. These tips can help your child cope with allergy season — and they work just as well for adults, too.

Babies who show certain digestive symptoms may be incorrectly diagnosed with cow’s milk allergy and put on special diets, although this allergy is uncommon.