Took mucinex (guaifenesin) dm xs for a bad cough with yellow mucus. it worked great , but i feel like i'm drunk and spaced out . is this a normal side effect ??

Yes: Yes you can have those symptoms. Reference: drugs.comNervous system side effects of dextromethorphan have included drowsiness and dizziness. Adverse effects, which have occurred at higher doses, include excitation, mental confusion, and opioid like respiratory depression. In some cases of abuse, patients have experienced euphoria, hyperactivity, mania, and auditory and visual hallucinations.