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A 45-year-old member asked:

what causes asthma?

7 doctor answers22 doctors weighed in
Dr. Sean McGhee
Allergy and Immunology 23 years experience
Genes + environment: People with asthma usually are predisposed to be allergic. This is usually inherited, and so caused by your particular genes. However, this alone is not enough. There is also clearly an effect from the environment you live in. Exactly what in the environment is responsible is unknown, but is the object of much interest and research.
Dr. Joram Seggev
Specializes in Allergy and Immunology
Also infection: While 80% of asthma patients have allergies, there are patients whose asthma starts after they had a respiratory infection. Those infections can be due to viruses such as influenza (the real flu) or certain bacteria such as mycoplasma or chlamydia. Such patients are usually older and have no history of allergy. Still, patients who already have asthma and get infected, their asthma will get worse.
Dr. Michael Rupp
Allergy and Immunology 21 years experience
Allergies: The majority of childhood asthma is caused by allergies creating inflammation in the lungs which leads to narrowing of the air tubes in the lungs and trouble breathing. Infection certainly can cause symptoms that look like asthma. In children this often occurs after illnesses like RSV, influenza, parainfluenza, and even the common cold has been shown to have this effect.
Dr. John Chiu
Dr. John Chiu answered
Allergy and Immunology 57 years experience
Repair defect: Although over 50% of asthma is related to allergies, allergies do not cause asthma in everyone who is allergic. The current focus is on the malfunctioning repair mechanism in the epithelium of the airways which apparently is abnormal in people suffering from asthma. Many thing can trigger the damage (diesel particles, allergens, virus) the end result is narrowing of the airways. Sounds too complex
Dr. Joram Seggev
Specializes in Allergy and Immunology
The above mechanism may be the common denominator, it still does not explain the vast spectrum of asthma. There are patients who wheeze once a year; the "typical" allergic asthmatics with symptoms only during allergen exposure; "post infection" asthmatics with no personal or family history of atopy; the patients with rapidly deteriorating lung function. Asthma may well be more than one disease.
Sep 2, 2014
Dr. John Chiu
Dr. John Chiu answered
Allergy and Immunology 57 years experience
Many: Although the exact cause(s) for asthma is being debated, about 80% of asthma especially among younger people are related to allergy. Current thinking is that a viral infection is likely the trigger for its development. More recently, an abnormal epithelium (which covers the airways) is considered a major component for the development of asthma. A detailed review is not feasible .
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Asthma: Asthma is caused by reactive airways that results in excess mucous production + narrowed airways. Symptoms are usually episodic and triggered by allergies (grasses, pollen, mould) or infections. Some people get exercise-induced symptoms.
Dr. James Ferguson
Pediatrics 46 years experience
Genetics/external fr: There is ample evidence that true asthma is genetically linked to the issues of allergy & eczema & frequency is higher when one or both parents are affected. Lower respiratory tract viruses often trigger both infectious wheezing & that of true asthma early on with infectious wheezing subsiding after 3-4y. Allergies often co-exist but less than 5% of events are allergy driven alone.

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Similar questions

A 18-year-old member asked:

Can smoking pot cause asthma?

4 doctor answers20 doctors weighed in
Dr. Edward Neilsen
Family Medicine 19 years experience
COPD: Not asthma, but smoking anything can lead to COPD (bronchitis or emphysema). Unfortunately, this is worse than asthma because asthma is reversible, but COPD is chronic. Be smart...Don't put anything in your lungs!
Dr. Jack Mutnick
Allergy and Immunology 17 years experience
That is not entirely true. Both diseases are equally awful with long drawn out deaths due to COPD while asthma exacerbations can kill instantaneously. No proof that MJ does NOT contribute to asthma.
Jan 19, 2012
A 29-year-old member asked:

What is the cause of asthma?

4 doctor answers13 doctors weighed in
Dr. Cornelia Franz
Specializes in Pediatrics
Inflammation: Is the precipitating cause but no one really knows the actual underlying reason some people develop asthma. We do know that allergies and respiratory infections can lead to inflammation that leads to wheezing and "asthma" symptoms. Diet and genetics my also influence developing asthma.
A 41-year-old member asked:

What usually causes asthma?

2 doctor answers7 doctors weighed in
Dr. Richard Williams
Pharmacy 18 years experience
Numerous reasons: In children asthma is often linked to allergies. As we age, exercise induced asthma , occupational asthma and attacks not related to allergies play a larger part. In addition, asthma is sometimes mistaken for something else. Get checked to make sure.
Dr. Michael Zacharisen
Allergy and Immunology 33 years experience
I agree with Dr. Williams. Other common triggers of asthma include infections especially viral colds, sinus infections, cold/dry air and even GE (acid) reflux.
Jun 11, 2013
A 49-year-old member asked:

Can firsthand smoking cause asthma?

1 doctor answer2 doctors weighed in
Dr. Azmat Qayyum
Pulmonary Critical Care 33 years experience
May be: Many times even. Doc. Call. Copd. Asthma. I have heard patients thinking all their lives they have. Asthma but had. COPD . Smoking is culprit in causing copd. And smoking. Worsens. Asthma. Copd. Is irreversible. Smokers. Are the one who get COPD
Dr. John Chiu
Dr. John Chiu commented
Allergy and Immunology 57 years experience
Certainly it increases the risk of one's children in developing asthma from second-hand smoke exposure. Smoking makes asthma less responsive to inhaled cortisone and causes problems noted above but I have not heard of any evidence showing that it directly causes asthma.
Nov 5, 2013
Gonzales, LA
A 44-year-old male asked:

What causes frequent asthma?

2 doctor answers4 doctors weighed in
Dr. David Houghton
Specializes in Internal Medicine and Pediatrics
Lots of things: There are many asthma triggers. In some cases they can be identified & avoided, or desensitization therapy by an allergist might help. But in most cases, the triggers are difficult if not impossible to avoid, and the answer lies in calming down the asthma response with an inhaled corticosteroid. If asthma symptoms are frequent or severe, increased treatment is needed to avoid serious consequences.

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