Some years ago I was advised , that in order to check the contents of my inhaler I should remove the pressurised phial from the applicator and suspend the phial in a tall glass of water.
If it sinks ,the indications are there is medicine present and if it floats there is probably little or no medicine present ,only propellant . I know you have to shake the inhaler prior to use, which I do ,but it seems to me that it is still running out very quickly.
In particular I am referring to the 'Ventolin' I am prescribed as a reliever for as and when , so it's used often ,depending on circumstances. In the winter time especially it barely lasts a fortnight
I'd like to know what others think about this