Your 12 Worst Allergy Mistakes

You Leave Windows Open

Make it a rule to keep your windows closed and the air conditioner on when it's pollen season.

Be sure to set the AC to "recirculate," and if it's not hot outside, you can keep it in filter-only mode. Using an air conditioner in your car can cut the amount of pollen you breathe by as much as 30%, says Myngoc Nguyen, MD, chief of allergy at Kaiser Permanente Medical Center, Northern California.

You Delay Medication

• As seasons change, plants spew pollen. So try to anticipate and treat yourself before that happens. Same goes if you know you'll be visiting a cat-loving friend, and felines are your worst symptom trigger.
• "These medications almost all work better to prevent allergy symptoms than they do to treat them, so people should not wait until they're having symptoms to start taking their medicines," says David Rosenstreich, MD, the director of the Division of Allergy and Immunology at Montefiore Medical Center in the Bronx, New York.
• Same with asthma. Don't skip controller meds until you're short of breath. "It's easier to fix the problems when they're mild."

You Ignore Pollen Counts

• "People should make an effort to be aware of the pollen count and when the pollens are out that bother them," says Dr. Rosenstreich.
• Check out pollen.com to find out exactly when allergy season begins in your area.
• You can also use the site to look up four-day allergy forecasts for your zip code, and sign up to get allergy alerts by email. The more information you have, the better prepared you'll be to manage your symptoms.

You Exercise at the Wrong Time

If you love an outdoor workout, avoid the morning or early afternoon, says Dr. Nguyen.

Grasses and trees start releasing pollen at sunrise, with levels peaking in the late morning and early afternoon. "I always suggest people run after work in the late afternoon or evening," she says.

Exercising when pollen counts are lower, Dr. Rosenstreich agrees, "can make an enormous difference." And if pollen counts are going to be high on a given day, opt for a less strenuous workout.

You Undermine Your Air Purifier

• Room air purifiers and filters are an extremely effective way to remove pollen, animal dander, dust, and other allergens from indoor air. (Find out how to buy the right air cleaner.)
• But unless you close the doors and windows in the room where you're using one, it's basically useless because they're only meant to filter room-size areas—not your entire house, or the great outdoors.

Your EpiPen Is Expired

"If you need to carry an EpiPen (an auotinjector) because you're at high risk of a serious allergic reaction, check every year to make sure its expiration date hasn't passed, and replace it if it has," Dr. Rosenstreich says.

It's also a bad idea to keep your EpiPen in the car, where it can be exposed to temperature extremes that make it less effective.

Be sure to learn how to use it properly, Dr. Rosenstreich advises. "You don't want to start reading the label in the middle of an attack." Finally, he adds, be aware that once the safety cap is off, the needle will inject anything it touches.

You've Got Clutter

Stuffed animals are cute, cuddly, and unfortunately, major magnets for dust, a common allergy trigger.

If your child has piles of fluffy friends, and he or she—or anyone in the household—has allergies, you're better off storing or giving them away. (Many charities collect stuffed animals to give to needy kids, or even as puppy play toys.)

"It's best to limit youngsters to a select few, which can be occasionally washed, rather than a whole collection," Dr. Rosenstreich says.

You Ignore Symptoms

Adults can become allergic to pets or pollen after years of allergy-free living.

If you need antibiotics for sinusitis every spring, you may have a pollen allergy, says Dr. Nguyen, who recommends a visit to the allergist. "Repeated use of antibiotics is not necessary, can lead to drug allergy, and doesn't help the pollen allergy," she says.

You can become allergic to a pet and not know it because symptoms are subtle and chronic. If you've got allergy-ish symptoms that never go away, get it checked out.

You're Down With Down

Love that cozy comforter? It might be trouble, particularly if you've had it for a long time.

"Feathers can be very allergenic, and become even more so as they age and break down," says Dr. Rosenstreich. "I'll have people tell me, 'I've had this feather pillow for 40 years, I brought it from Romania, it's never bothered me before,'" he adds. "That's precisely the point."

Synthetic pillow stuffing, like polyester fiberfill, is a better choice for people with allergies. You can make your pillows even less sneeze-inducing by getting dust mite-proof covers for them (and while you're at it, for your mattress).

You Sleep With Your Pet

It may seem sweet to snooze with your pup or kitty at night, but it's not a great idea if you have allergies.

Even if you're not allergic to animals, pets can bring in pollen, dust, mold, and other allergens from the outdoors, Dr. Rosenstreich notes. It's best to avoid letting your dog or cat hang out on your bed.

"Your bedroom should essentially be an allergy-free zone," he says. For the same reason, you're better off with bare floors in the bedroom, or only using a rug or two that you can throw in the wash periodically.

You Get a Hypoallergenic Pet

• Sorry folks, but there's no such animal as a truly hypoallergenic pet. (Beyond a snake or lizard.)
• While some breeds are said to be less allergy-inducing than others, experts say any furry animal can cause symptoms in susceptible individuals.
• Even hairless cats and dogs are allergenic; it's not the fur that makes people sneeze, but flakes of skin called dander and proteins found in the animals' saliva and urine.

You Think a Bird Is Ok

"People can be allergic to birds, too," Dr. Rosenstreich warns.

"A single big bird can cause a lot of problems for people, and often they will not realize it because allergy can take a long time to develop," he says.

Allergists advise against living with an animal if you're allergic to it. If you can't or don't want to find a new home for your beloved pet, consider allergy shots, which can help reduce symptoms in some people.