Anxiety is not a common side-effect of Mucinex, however you said you were taking a supplement that contains (has) similar ingredients perhaps there is something extra in the supplement or perhaps the supplement doesnt actually contain what you think it does There have been several scandals recently where supplements were not as advertised. Talk to your pharmacist (or other medical specialist). When you do - make sure you provide a complete list of everything you are taking prescriptions, OTCs, herbs, or other supplements.

[Anxiety is a common side-effect of COPD in general. If you have trouble breathing one tends to get anxious.]

Mucinex helps by thinning mucus and making it easier to cough up. BUT if after thinning you are still coughing up large amounts, you anxiety is increasing, and/or you have a fever or other side-effects seek immediate medical attention.

i dassaggree there are numerous articles that state that guaifenesin causes hyper,but i always like to get feed back from members who have used it,thanks for the reply

of i take just the guaifenesin i have no problem, but if i accidently get a medication that has a decongestant like pseudoephedrine and phenylephrine i have racing heart & high anxiety.
if your anxiety is bad with it you may want to ask your dr for an alternative medication.
I have found also that the mucinex pills are too strong for me & i feel "weird" if i take that much so i buy a liquid guaifenesin that i can take 1/2 the recommended dosage...the liquid also works faster for me as i just use it 'as needed'.

thanks for the repies