Asthma is a chronic lung disease that cannot be cured - only controlled. When you have asthma, your airways are super sensitive. They react to many irritants, such as cigarette smoke, pollen, animals, or cold air.

Asthma affects the airways in your lungs. During an episode of asthma:

• The lining of the airways becomes swollen (inflamed).
• The airways produce a thick mucus.
• The muscles around the airways tighten and make the airways narrower.

These changes in the airways block the flow of air, making it hard to breathe.

What Causes Asthma Symptoms to Appear?

Substances that you may inhale can cause allergy symptoms or can also trigger an asthma episode. Dust mites, pollens, molds, pet dander and even cockroach droppings may cause you to have asthma symptoms. It is best to avoid or limit your exposure to known allergens in order to prevent asthma symptoms.

• Irritants in the air including smoke from cigarettes, wood fires, or charcoal grills can cause asthma symptoms to appear. Also, strong fumes or odors like household sprays, paint, gasoline, perfumes, and scented soaps can be an irritant and can aggravate inflamed, sensitive airways. 
    
• Respiratory infections such as colds, flu, sore throats, and sinus infections may cause asthma symptoms.
    
• Exercise, especially in cold air, can be a frequent asthma trigger. A form of asthma called exercise-induced asthma is triggered by physical activity. Symptoms of this kind of asthma may not appear until after several minutes of sustained exercise. When symptoms appear sooner than this, it usually means that the person needs to adjust his or her treatment. 
    
• Other types of exertions can bring on asthma symptoms including laughing, crying, holding one's breath, and hyperventilating (rapid, shallow breathing). When you experience strong emotions, your breathing changes -- even if you don’t have asthma. When a person with asthma laughs, yells, or cries hard, natural airway changes may cause wheezing or other asthma symptoms. 
    
• Weather such as dry wind, cold air, or sudden changes in weather can sometimes bring on an asthma episode. 
  Some medications like aspirin can also be related to episodes in adults who are sensitive to aspirin.

What Are Allergies?

Allergy may be defined as an unusual reaction to normally harmless substances that contact the body surfaces. These surfaces include the eyes, nose, lungs, stomach and skin. Allergies reflect an overreaction of the immune system to certain substances which can cause sneezing, wheezing, coughing and itching.

What Are the Most Common Causes of Allergic Reactions?

• Dust Mites are microscopic and thus cannot be seen by the naked eye. They are part of the arthropod (spider) family, and thrive in warm indoor moist environments. They feed chiefly on the tiny flakes of human skin that we normally shed each day. Dust mite droppings break down to an extremely fine powder and stick to indoor materials. The waste products (droppings of the dust mite) contain a protein that is an allergen and that causes an allergic reaction.
  
  To reduce dust mite allergen in your bedroom, vacuum often, enclose your mattress, box spring and pillows in zippered dust proof covers, and wash your bedding in hot water of 130 degrees Fahrenheit.
    
• Pollens is a very fine powder released by trees, weeds and grasses. It is carried to another plant of the same kind to help fertilize new seeds.
  
  Trees pollinate in late winter and spring. Ash, beech, birch, cedar, cottonwood, box, elder, elm, hickory, maple and oak pollen can trigger allergies. Grasses pollinate in late spring and summer. Those that cause allergic reactions include Kentucky bluegrass, timothy, Johnson, Bermuda, redtop, orchard, rye and sweet vernal grasses. Weeds pollinate in late summer and fall. The weed that causes 75 percent of all hay fever is ragweed which has numerous species. One ragweed plant is estimated to produce up to 1 billion pollen grains. Other weeds that cause allergic reactions are cocklebur, lamb's quarters, plantain, pigweed, tumbleweed or Russian thistle and sagebrush. Click here for photos.
    
  Pollen counts are highest in the morning, shortly after dawn. To shut out pollen, keep your doors and windows closed.
    
• Molds spores grow in moist areas. Spores float in the air and inhaling them causes allergic reactions in some people. Spores are found outdoors and indoors and their levels peak in the late summer and fall months.
    
  Outdoor molds commonly grow in moist, shady areas such as in soil, decaying vegetation, leaves and rotten wood. Cladosporium and Alternaria are common outdoor molds. Indoor molds are found in dark, warm, humid areas inside the home including basements, cellars, attics and bathrooms. Mucor, Aspergillus and Penicillium are common indoor molds.
    
  Reducing the amount of moisture in your home can reduce the amount of mold. Fix any faucets that are leaking inside and outside your home. Clean moldy surfaces and reduce the number of houseplants.
    
• Animals - Proteins found in the saliva, dander (dead skin flakes) or urine of furry animals can cause allergic reactions. These proteins are carried in the air and can land on the lining of the eyes or nose, or be inhaled directly into the lungs. 
    
  To reduce pet allergen, avoid pets. If a pet lives in your home, you should at least keep it out of your bedroom.
  
• Cockroaches live in the offices and homes of people who inadvertently provide them with the water and food they need to survive. The protein in their droppings can cause asthma symptoms, especially for children living in densely populated urban neighborhoods.
  
• Mice and Rats - The protein found in the droppings and urine of these rodents has recently been found to cause asthma symptoms. Similar to cockroaches, they are found in urban neighborhoods where food and water is accessible to them.
    
• Food - Food allergy occurs when a person’s immune system overreacts to an ordinarily harmless food. About 8%, of children in the United States are estimated to be affected by food allergy and up to 2% of adults.
    
  The most common food allergens responsible for up to 90% of all allergic reactions, are proteins in cow’s milk, eggs, peanuts, wheat, soy, fish, shellfish and tree nuts. Symptoms of food allergy are hives, eczema, asthma and gastrointestinal symptoms such as vomiting, diarrhea and abdominal cramping.
    
  The most severe reaction to food is anaphylaxis, a systemic allergic reaction that can sometimes be fatal. The first signs of anaphylaxis may be a feeling of warmth, flushing, tingling in the mouth or a red, itchy rash. These symptoms can be reversed by treatment with injectable epinephrine, antihistamines and other emergency measures, with follow-up care by an allergist.
    
• Sulfite Sensitivity and Food - Sulfites are used to eliminate bacteria, preserve freshness and brightness, prolong crispness, prevent browning and increase storage life of certain food and drug products. Some people are hypersensitive to sulfating agents. Read the labels on all foods that you buy. You can identify sulfite agents by noting the following labeling terms- sulfur dioxide and potassium or sodium bisulfite.
    
• Latex, produced by rubber trees, is processed into a variety of products. Products that commonly cause reactions include gloves, balloons and condoms. Some latex allergic individuals may also react to rubber bands, erasers, rubber parts of toys, various medical devices, latex clothing and elastic in clothes, feeding nipples and pacifiers.
    
• Insect Stings - An estimated 3% of the population is susceptible to allergic reactions to stinging insects, including, yellow jackets, honeybees, paper wasps, hornets and fire ants. About 50 deaths occur each year as a result of their stings.
    
  For some people, stings may be life-threatening, resulting in anaphylaxis. Symptoms may include itching and hives over large areas of the body, swelling in the throat or tongue, difficulty in breathing, dizziness, stomach cramps, nausea or diarrhea. In very severe cases, a rapid fall in blood pressure may result in shock and loss of consciousness.

The information provided is for reference only and should not substitute for professional medical care.