Can I use Primatene Mist for Asthma

I am in the FL IPN program with monthly UDS etc. I have Asthma but right now am financially unable to visit a Dr for an inhaler - I usually use a Combivent once a day and have a rescue breather available. I can feel the asthma starting to kick up, and wondered if I could use Primatene Mist until I can get to a Dr...anyone know if it causes false positives on urine drug screens...I sure do not want to mess up anything. Thanx.