I'm sure there is a place on here somewhere that tells what medicines and other things to avoid. I have a cold and have wondered if things like tylenol or nyquil will further worsen nerve damage. If someone could point me in the direction of where all this information is listed I would appreciate it.

Normal use of cold medicines is not a problem. Continued use of decongestants, may increase vasoconstriction in some people however.. so avoiding those may help with PN that is vascular in origin. Nyquil has alot of alcohol..so those with alcohol issues should avoid. Many cold products have this listed on the labels.
The AlkaSeltzer cold products obviously are alcohol free.

Avoid certain antibiotics...metronidazole, Cipro, Levaquin, Avelox.
Some others less commonly used. Zyvox, Tindamax.

Avoid macrobid for UTI's.
Avoid statins.

People using, tricyclic antidepressants like amitriptyline etc, SSRI antidepressants or SNRIs should avoid products with DM in them (dextromethorphan).

I found that DM actually helps sometimes with PN pain sometimes... but you can't use it with antidepressants (including amitriptyline etc).

Tylenol is okay in moderation, but people with liver disease need doctor supervision.