Asthma is a common chronic health problem in the US and many other countries around the world. It is becoming especially common in children.  But people of any age can develop asthma, even senior citizens.

However, asthma symptoms are often similar to the symptoms of other respiratory illnesses. So, how does a doctor make the decision that what you have is asthma?

In adults, doctors can rely on a history of your symptoms, i.e., when they occur, how often, and how long they last. The key symptoms your doctor will ask you about include:

• Cough, which is worse at night
• Frequent wheezing
• Frequent shortness of breath
• Frequent chest tightness

Another question your doctor may ask is if you notice your symptoms get worse with exposure to any of the following factors:

• Exercise
• Viral infection
• Animals with either fur or feathers
• House dust mites (found in mattresses, overstuffed furniture, carpets, pillows)
• Mold, either outdoors or indoors
• Tobacco or wood smoke
• Pollen from grass, trees, or weeds
• Changes in weather, especially cold weather
• Strong laughing or crying or emotional stress
• Chemical fumes or dusts
• Menses

Also, if your symptoms get worse at night and prevent you from sleeping, that's a strong indication that asthma may be at work on your airways.

The doctor will also take a look at your family history of allergies and asthma, because asthma does tend to "run" in families. And even if no one in your family ever had asthma, but they did have allergies, you are probably at a higher risk for asthma than people who don't have a family history of allergies.

Besides your personal and family health history, the doctor may perform some tests to help him or her make the diagnosis. A peak flow meter is a device that doctors can use to measure how well your lungs are working. It's a handheld device that you blow into. It measures what is called Peak Expiratory Flow, or PEF for short. When the PEF varies by 20 percent or more between the first thing in the morning and early afternoon, your doctor will suspect asthma.

Another test that is sometimes used is called spirometry. This is a machine that can measure the amount and rate of air you breathe with more accuracy than a peak flow meter.

Diagnosing asthma in young children is harder. To begin with, a child may not be able to describe how he or she is feeling as well as an adult can. So, the doctor will need to rely on the observations of the parent. One of the most common symptoms of asthma in children is a chronic cough, so if you notice that in your child, talk with your doctor.

Doctors may not always be able to say for sure a child has asthma, so they may simply tell you that your child has "breathing problems." Nevertheless, your doctor will probably treat your child as if he or she did have asthma.

Once a doctor has made a diagnosis of asthma, then he or she will go on to classify your level of asthma. Classifying asthma helps guide the doctor in developing your asthma treatment plan. Here are the 4 main classifications: