I have a history of asthma and have a corticosteroid inhaler. if i'm sick, should i refrain from taking it since it's an immunosuppressant?

You should increase!: If your asthma gets worse, or if you have a viral cold, which causes asthma to get worse, you need to increase the use of your inhaled steroid. There is some debate whether you should double or quadruple (increase fourfold) the dose. There is increased hyperreactivity (twitchiness) of the airways that requires the increase. Inhaled steroids usually do not reduce immunity, .

Absolutely not!: The amount of medication absorbed into your body with inhaled steroids is minimal and does not cause immunosuppression. And if your illness has any effect on your asthma, such as a bad cold, respiratory tract infection, etc, then you should even think about increasing the dose during the illness. Excellent question, but stay on the medication!