Inhalers are devices to deliver the asthma medicines directly to site of action i.e. lungs.

The medicine delivered, acts locally in airways without getting absorbed into the body system, there by minimizing any side effects. 

More over a very small amount of medicine is required, as compared to oral drugs, since there is no wastage of drug due to destruction in body system. 

As the drug delivery is direct to the site of action, the onset of effect is very quick leading to rapid control of symptoms. 

Certain drugs like steroids, used for prevention of asthma can only be given safely through inhalation route. 

Safety

Minimal adverse side effects.

Quick onset of action.

Only way to abort asthma attack.

Only way to prevent asthma in future.

Only safe way to treat children and patients with coexisting diseases like heart diseases and high blood pressure.

Cost effective in long run, as prevents emergency admissions in hospitals by reducing chances of asthma attacks, and abort an asthma attack.

Only way to prevent long term complications of asthma, and allow patient to lead normal life with normal activities.

are mainstay of treatment as they reduce inflammation, remove inflammatory cells from around the airways, reduce mucus secretion into the constricted airways and decrease swelling in walls of airways. 

Used over a period of time, it decreases hyper reactive ness of the airways and thus have important role in long term prevention of asthma , and preserving normal anatomy and function of airways of lungs.

Used orally for prolonged period of time, steroids can produce several side effects like dependency, drug induced diabetes, drug induced high blood pressure, decreased immunity of body, weakening of bones etc.

However different types of inhalation steroids have been developed for local action in airways which are safe and free from side effects.  

More over, inhalation steroids are not absorbed in to the body system. 

These inhalation steroids have important role in treatment, prevention of asthma; and for preserving anatomy and function of airways. 

Asthma attacks usually give you warning signs before they start. This gives you time to "short circuit" the attack, but you must take immediate action. 

Go into action as soon as any of the following warning signs appear: tightness in your chest, coughing, wheezing, dyspnea (difficulty breathing), or shortness of breath. 

Take the mouthpiece and cap off. Fit the metal stem of the inhaler into the hole in the mouthpiece. Shake the inhaler 5 times.

Purse your lips and breathe out completely. Put the mouthpiece in your mouth, forming a seal with your lips and teeth.  (Make sure the inhaler is upside down.)

With your head tilted back slightly, take a slow, deep breath and press the inhaler down once. Keep breathing in until your lungs feel as if they are full of air. (Press the inhaler only one time. One press equals one dose.)

Remove the mouthpiece from your mouth. Hold your breath for 5 seconds. (Silently count one 100, two 100, three 100, four 100, five 100.) Purse your lips and breathe out slowly.

If your doctor has prescribed a second dose, wait 2 minutes before taking the second dose.

It takes a few minutes for the medication to completely open your airways. 

In the meantime, it's important that you try to relax, because fear and anxiety add to the shortness of breath. 

Do your pursed lip breathing until you no longer feel breathless. (Don't gasp for air! That only makes it worse.) 

Sit in a chair with your eyes closed, doing your pursed lip breathing for a minute or so. 

Now tighten the muscles in your forehead (frown as if you're furious!), hold it for 3 seconds, and relax those muscles. 

Next tighten the muscles in your lower face (clench your jaw in determination), hold it for 3 seconds, and relax. 

Now you're ready to tighten-relax your arms and hands, then your buttocks, then your legs and feet. 

After that, let your entire body go limp and feel how relaxed your muscles are.

Sit in a chair with your eyes closed, doing your pursed lip breathing for a minute or so. 

Now imagine the most peaceful scene you can think of--perhaps a calm lake, mountaintop at sunset, floating clouds, or whatever especially appeals to you. 

Visualize the scene, with you in it, in as much detail as possible. 

Repeat to yourself how relaxing it is to be in that place and how easily you can breathe there.

For example, you might tell yourself, "The air is so sweet and fresh here. Every time I breathe, the air cleanses my lungs and I can breathe more easily."

Asthma attacks sometimes trigger a coughing spell. This is actually good, because it brings up mucus and helps clear your airways.

But you need to be sure the coughing is effective. 

To do this, keep your feet on the floor and lean forward slightly. Breathe in deeply and hold it for 2 or 3 seconds. Cough to loosen the mucus. Cough again to bring the mucus up, spitting it into a tissue. (Don't swallow mucus because this can cause nausea.)