How old must a child be to use an inhaler?

Depends....: A child only needs to be old enough to be able to follow the command of "take a deep breath". For children, the almost mandatory use of an aerochamber and mask will help also help in improving the effects of an inhaler.

Any age: While obviously you would not want to use an asthma inhaler outside of a doctor's direction, modern inhalers are quite good and safe. There are simple devices called spacers which are prescribed by doctor that enable the inhaler to be used even on an infant (with a mask). Studies have shown inhalers to be as effective as nebulizers and have the advantage of being much faster.

Depends....: Although inhalers can be used in young children when administered by an adult, it still requires the ability to follow directions such as instructions to take a deep breath. Aerochambers and masks are often prescribed in young children to improve medication delivery. Alternatively a nebulizer may used to ensure adequate medication dosing.

Need deep inhalation: If they can follow the instruction and take the deep breathe to send the medicine down all the way, then they will have the benefits of the medicine, otherwise it won't be helpful. They have to hold the lips around the mouth piece good enough to inhale the medicine. If they can't, then treatment with nebulizer can give the medication continuously to the airways.