Is it safe to ride while taking mucinex (guaifenesin)? I've been getting over a chest cold, most of the worst symptoms are gone (like the sinus headache and tiredness).  However, I tend to have a bit of congestion that hangs around for a couple weeks after the other symptoms clear up.

I found that mucinex (guaifenesin) seems to help me with this since it thins the mucous in the lungs.  Is it safe to take this to be more comfortable on longer rides?  Is there anything I should be careful of?
Plain old Mucinex (without the "-D" suffix) is guaifenesin, one of the most innocuous drugs in existence.  Unless you have a peculiar (and rare) reaction to it, it should be about as safe as one can hope for.  In fact, I'd recommend it if you ride in dry or dusty conditions.

Mucinex-D, on the other hand, contains a decongestant that can cause drowsiness and other such symptoms in a substantial minority of patients.  (And I believe it can also be picked up in pro sports drug tests.)  You should take that while riding only after you've established that you don't react to it (and you're not in pro competition).

Also, of course, if you find yourself getting congested on rides that's a likely sign that you need to drink more water.