My youngest son has asthma, which presents as coughing. He started on brown and blue inhalers at 2 and a half, after two bad winters of coughing until he was sick.
In our case, he was a changed child after he started on the inhalers. His colour improved, he put on weight, slept better, ate better.
We currently find he needs the brown throughout the year, with a double dose in the winter months.
As regards the dose, the asthma nurse, who visited from the local NHS trust team, told me that even with good technique, a child only takes in 15% of the actual dose, and the levels are very safe.
Oh, ds's asthma cough is dry, and different from his more chesty cough when he gets a cold, but the inhaler shortens the length of time he takes to recover from a cold.