The number of people who develop asthma and allergies grows yearly. Understanding why and identifying and avoiding triggers may help you stay healthy.

There has been a steep rise in cases of asthma and allergies in the United States over the past few decades.

According to the American Lung Association, 41.9 million people in the U.S. had at one point received an asthma diagnosis. And the rate appears to be on the rise. Since 1999, this number has grown by 43%. The Centers for Disease Control and Prevention (CDC) estimates about 8.4% of U.S. adults have asthma.

Allergies, also known as allergic rhinitis, affect up to 30% of the U.S. population and are rising. According to the Asthma and Allergy Foundation of America, more than 100 million people in the U.S. experience some form of allergy each year. In fact, in the U.S., allergies are the sixth-leading cause of chronic illness.

Asthma is a chronic condition that affects the airways. Symptoms like wheezing, cough, and chest pain may come and go. Asthma affects people of all ages but most commonly starts in childhood. Children ages 5-17 have higher rates of asthma than any other age group.

Allergies occur when your body reacts to an otherwise harmless substance, like pollen or pet dander. Exposure to these triggers can cause allergy symptoms like itchy or watery eyes, sneezing, and runny nose.

And the two conditions often go hand in hand. Here’s what we know about the relationship between allergies and asthma and why both conditions are rising.

There’s no one explanation behind why allergies and asthma are on the rise. However, there are a few possible theories.

The “hygiene hypothesis” is the belief that over-sanitizing a child’s environment can lead to decreased disease resistance.

The increased use of certain medications, such as antibiotics and acetaminophen (Tylenol), may also contribute to asthma and allergies.

Rising levels of obesity may directly contribute to the increase in asthma. Similarly, decreased activity levels and poor diet are known to increase the risk of various types of chronic disease.

Vitamin D deficiency, which may result from spending too much time indoors, may also play a role in asthma cases. Exposure to the “sunshine vitamin” is crucial for lung and immune system development.

Many experts believe environmental factors also contribute to asthma and allergies. An increase in airborne pollens, climate change, and air pollution are all thought to play a role.

Allergies and asthma often go hand in hand. Allergens are even known to be the most common asthma trigger. This is known as allergic asthma.

Allergic asthma is the most common type of asthma. In fact, 90% of asthma cases in children and 50% of cases in adults are considered to be allergic asthma.

Allergens like pollen, dust, or pet dander trigger allergic asthma. Both allergic and nonallergic asthma can be exacerbated by exercise, stress, smoke, or airway infections.

Allergic rhinitis, allergic asthma, and nonallergic asthma share many triggers. Common indoor and outdoor triggers include:

  • some medications (antibiotics, acetaminophen)
  • changes in weather
  • dust
  • exercise
  • food allergy
  • Illness (cold, flu)
  • mold
  • pet dander
  • pests (roaches, mice)
  • pollen
  • smoke exposure

Nonallergic asthma may also be triggered by:

  • acid reflux
  • strong emotions
  • strong odors or fragrances

There are many ways to minimize allergens in your home and make it a safer environment. Start with these strategies.

  1. Avoid smoking and exposure to secondhand smoke: Do not smoke inside your home or car. If you smoke, choose a “smoking jacket” or other clothing used when smoking outdoors that you can remove before coming into contact with others.
  2. Be mindful when cleaning: If you notice certain cleaning products trigger your asthma, avoid using these in your home, or wear a mask when cleaning with them.
  3. Dust mite-proof your home: Buy “dust-mite impermeable” covers for mattresses, duvets, and pillows. Wash bedspreads and linens once a week. Vacuum regularly to keep dust mites at bay.
  4. Keep pollen out: Check pollen counts and stay indoors when they’re high. Shut windows and use air conditioning in warmer months. Take a nightly bath or shower to remove pollen from your skin and hair.
  5. Eliminate mold: Fix water leaks promptly and keep areas like sinks and bathtubs clean and dry. Run a fan and use a dehumidifier as needed.
  6. Consider pets without fur or feathers: If you have pets, bathe them weekly. Keep them off of furniture, beds, and toys. Vacuum weekly to remove pet dander.
  7. Take steps to avoid pests: Don’t leave food or crumbs lying out. De-clutter any boxes, bags, and papers you may have lying around. Contact pest control if you have pests, such as mice and cockroaches, in your home.
  8. If you have food allergies, be mindful of food triggers. Common food allergies include milk products, peanuts, tree nuts, eggs, sesame, soy, wheat, fish, or shellfish. If there is a possible food allergy, refrain from eating those foods and contact your doctor right away. If you’re diagnosed with a food allergy, always have epinephrine with you.

If you have asthma or allergies, talk with a doctor about your symptoms. Get tested to see whether allergens trigger your asthma. See an allergist or asthma specialist for an allergy and asthma action plan.