Causes

An overly sensitive immune system makes your airways (bronchial tubes) become inflamed and swollen when you're exposed to certain triggers. Asthma triggers vary from person to person. Common asthma attack triggers include:

• Pollen, pets, mold and dust mites
• Upper respiratory infections
• Tobacco smoke
• Inhaling cold, dry air
• Gastroesophageal reflux disease (GERD)
• Stress

For many people, asthma symptoms get worse with respiratory infections, such as those caused by the common cold. Some people have asthma flare-ups caused by something in their work environment. Sometimes, there isn't an apparent cause for an asthma attack.