Asthma is caused by narrowing of the tubes ( bronchi ) which 
carry air into the lungs. There are two ways in which these tubes
can become narrow.
1

 The walls of the tubes contain muscle fibres. When these 
contract the airways narrow and you wheeze, feel breathless 
or cough. This can be set off by cold air, pollen, cigarette smoke,
pets and several other things you may have noticed. Salbutamol 
(Ventolin, Salamol, Aerolin ) relaxes these muscle fibres within a 
few minutes. You notice this as your breathing gets easier 5 or 10 
minutes after you take the inhaler. The effect only lasts for a few
hours and doesn't improve the control of your asthma in the long run.

2

If you are stung by a bee or sprain your ankle you can see skin 
swelling and becoming red. This is called inflammation.In asthmatics
the same process occurs in the lining of the bronchial tubes. Swelling 
of the lining makes the airway narrower. It also makes the muscle in
the wall more 'trigger-happy'. This occurs over a period of  days or 
weeks unlike the sudden changes that I described in (1). You may
experience this as a gradual worsening of your asthma. You may begin 
to have problems at night, feel tight in the mornings or suffer frequent attacks
of wheeziness. These problems may persist even if you are using your 
salbutamol inhaler.
A steroid inhaler such as Beclomethasone (Becotide), Budesonide
(Pulmicort) or Fluticasone (Flixotide) reduces this inflammation.
Unlike the salbutamol which has an instant effect the effects take several 
days to come on. You should then feel your asthma improving and should 
need to use less of the salbutamol. Ultimately it is the steroid inhaler which 
will allow you to be free of symptoms. If  you still have symptoms despite
the steroid inhaler you are not on the right dose
Controlling your asthma
Patient information
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