I took Mucinex Fast-Max Day Severe Cold yesterday and then took a 5mg Oxycodone tablet 2 hrs later. about an hour and 1/2 after taking the oxyxodone, My legs collapsed while I was in the bathroom getting ready for bed. I was conscious but legs were really rubbery. I had a mastectomy on Sept 20th. i have not been taking the oxycodone every day but the coughing is making me sore.