2015年10月19日 星期一

Allergic Asthma - 過敏性哮喘

What is Allergic Asthma?
If you ever have trouble breathing during allergy season, you may have allergic asthma. Allergic asthma is asthma caused by an allergic reaction. It is also called allergy-induced asthma.

People with allergic asthma usually start feeling symptoms after inhaling an allergen such as pollen. The Asthma and Allergy Foundation of America reports that more than half of asthma sufferers have allergic asthma. Allergic asthma is treatable in most cases.

Causes
People develop allergies when their immune system overreacts to the presence of a harmless substance. This substance is known as an allergen. Common symptoms of allergies include itching and swelling. However, some people may also develop breathing problems from inhaled allergens. This is known as allergic asthma. It occurs when the airways swell as part of an allergic reaction.

In general, only inhaled allergens cause allergic asthma. Some allergens which can cause this condition include:
pollen
pet dander
dust
Cockroaches, milk, fish, shellfish, eggs, peanuts, and tree nuts can also cause allergic asthma. However, an asthmatic reaction to these allergens is less common.

Symptoms

Symptoms of allergic asthma are the same as symptom of regular asthma. They include:
wheezing
coughing
chest tightness
rapid breathing
shortness of breath

If you have hay fever or skin allergies to the allergen causing your asthma, you might also experience:
itchy skin
rash
flaky skin
runny nose
itchy eyes
watery eyes
congestion

If you swallowed the allergen, these symptoms might be present as well:
hives
swollen face or tongue
tingly mouth
swollen mouth, throat, or lips
anaphylaxis (severe allergic reaction)

Diagnosis
Skin prick tests are commonly used to check for allergies. Your doctor will poke your skin with a needle containing a small amount of allergen. After 20 minutes, your skin will be checked for red bumps. These bumps are the sign of an allergic reaction.

Additional tests may be used to check whether your allergies are accompanied by asthma.

Spirometry measures the amount of air you inhale and exhale. This test looks for narrowing in the bronchial tubes of your lungs.

Peak Flow measures air pressure as you breathe out. This is a simple test of lung function.

Lung function tests check whether your breathing improves after you use an asthma medication (bronchodilator). If this medication improves your breathing, you probably have asthma.

Treatment
Treating allergic asthma can involve treating the allergy, the asthma, or both.

To treat your asthma, your doctor may prescribe two inhalers. The asthma inhaler is used to prevent asthma. The fast-acting relief inhaler is used to treat asthma symptoms.

Allergy treatment depends on the severity of your symptoms. You may need an antihistamine to deal with classic allergy symptoms such as itching. You might also need allergy shots if your symptoms are more severe.

Complications
Allergic asthma can have serious complications. One such complication is anaphylaxis. This type of severe allergic reaction may have symptoms such as:

hives
mouth or facial swelling
difficulty swallowing
anxiety
confusion
cough
diarrhea
fainting
nasal congestion
slurred speech
slurring
Untreated anaphylaxis can be life-threatening. It may cause problems such as an abnormal heart rate, weakness, low blood pressure, rapid pulse, cardiac arrest, and pulmonary arrest.

Prevention

Allergic asthma attacks are not always preventable. However, you may be able to make them less common by changing your environment.

At Home
Dust and vacuum regularly and use a HEPA filter. This can reduce the number of allergens in your environment.

Keep your windows and doors closed when pollen counts are high. Pollen is a common allergen. It triggers asthma-like symptoms in people with hay fever. If pollen makes you wheeze, see your doctor.

Don’t use an air conditioner or fan that smells like mold. Purchase new appliances if necessary. Mold can trigger asthma and allergy symptoms. It is also potentially life-threatening when inhaled. Remove any traces of mold from your walls or floors using a mold-removing cleaner.

Additional Measures
Use a dehumidifier or air conditioner if the humidity in your home gets above 40 percent.
Avoid keeping animals indoors if you have pet allergies. With severe allergies, you may need to avoid animals completely.

Clean and disinfect your kitchen and bathroom to prevent cockroaches.
Wear a HEPA mask when you garden. This can help you avoid inhaling pollen or mold.

Source: http://www.healthline.com/health/asthma/allergic-asthma#Causes2

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