Allergens

• Pollen

• Grasses and trees

• Mold

• Dust

• Cockroach droppings

Respiratory infections

• Colds

• The flu

• Sore throat

• sinus infection

Irritants

• Strong odors and sprays, such as perfumes, household cleaners, paints, and varnishes

• Chemicals, such as coal, chalk dust, or talcum powder

• Air pollutants, such as ozone and chemicals in the air

• Weather conditions, including cold or wind

• Chemical exposure on the job, such as dust, gases, or fumes

Sensitivity to medications

• Aspirin

• Nonsteroidal anti-inflammatory medications, such as ibuprofen, indomethacin, and naproxen

• Sulfites used as preservatives in food and beverage

Exercise

• Strenuous physical exercise 

• Long-term activities, such as long-distance running

Other conditions

• Gastroesophageal reflux (GERD)

• Overweight

• Obstructive sleep apnea

Smoke

• Tobacco smoke, both inhaled and secondhand

• Smoke from wood-burning stoves and fireplaces

Emotions

• Anxiety

• Stress

• Depression