Asthma Causes

There isn't a single cause of asthma. Asthma appears to be a combination of genetic and environmental factors. It runs in families, and the risk of developing asthma is greater if both parents have asthma than if only one parent has the disease.

Children who develop asthma often have a genetic predisposition to become sensitized to environmental allergens and other respiratory irritants. Moreover, an early exposure to allergens, tobacco smoke, and viruses appears to increase the likelihood that a person will develop asthma.

Asthma often starts in childhood and is one of the most common chronic childhood diseases. Although asthma is more common in young boys than girls, this changes during adolescence when more females have asthma than males. Moreover, the number of children with asthma is growing. Although the exact reason for the increase is unknown, two theories are that children today:

• Are exposed to more allergens
• Aren't exposed to as many childhood illnesses to strengthen their immune systems.

Asthma is also more common and often more serious among African Americans. Although the exact cause is unknown, possible causes include:

• Socioeconomic factors, such as exposure to pollution in cities, cigarette smoke, inadequate prenatal care, and obesity.
• Genetic differences.

Asthma triggers

An asthma attack often occurs after a susceptible person is exposed to one or more triggers. Common asthma triggers include:

• Allergens
  • Animal dander (from skin, hair, or feathers)
  • Cockroaches
  • Dust mites
  • Mold
  • Pollen
• Certain medications
  • Aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs)
  • Beta blockers (treat high blood pressure, heart problems, and migraines)
• Cold air or weather changes
• Emotions
  • Anger
  • Crying, laughing, or yelling
  • Excitement
  • Fear
  • Stress
• Exercise
• Gastroesophageal reflux disease (GERD), which causes heartburn
• Respiratory irritants
  • Air pollution
  • Fumes from burning wood or gas
  • Tobacco smoke
• Strong odors
  • Chemicals
  • Cooking
  • Paints
  • Perfumes and scented products
• Sulfite preservatives in food and beverages
• Respiratory infections
  • Common cold
  • Flu
  • Sinusitis
  • Sore throat

By identifying which allergens and irritants trigger their asthma attacks, people can try to avoid or limit exposure to them. When avoidance of known triggers isn't possible, people can take medications to prevent or lessen the severity of an asthma attack.

How the lungs react

When susceptible people are exposed to an asthma trigger, the sensitive airways in their lungs overreact and make it difficult to breathe:

• The cells in the airways produce more mucus than usual.
• The airways become inflamed (swollen).
• The muscles surrounding the airways tighten, causing the airways to narrow.

These changes produce the symptoms of an asthma attack. Asthma quick-relief medications help open the narrow airways in the lungs and may stop an asthma attack.