People with asthma are usually sensitive to one or more substances that cause them to have symptoms. Common asthma triggers include:

• Upper respiratory infections
• Colds and flu
• Bronchitis
• Sinus infections
• Outdoor allergens
• Tree, grass, weed pollens
• Mold spores
• Indoor allergens
• Molds
• Animal dander or hair
• Dust mites
• Cockroaches
• Exercise
• Irritants
• Cigarette smoke
• Smoke from wood-burning appliances or fireplaces
• Strong odors (perfumes, cleaning agents, etc.)
• Air pollution
• Occupational dust and vapors
• Weather
• Cold air
• Changes in temperature and humidity
• Strong emotions
• Anxiety
• Crying
• Yelling
• Hard laughing
• Medications
• Aspirin
• Nonsteroidal anti-inflammatory drugs (Motrin, Advil)
• Gastroesophageal reflux disease (GERD)
• Food allergens

While not commonly associated with asthma, food allergies have been known to cause symptoms, particularly in young children