What OTC and prescriptions drugs should a nursing mom avoid?

Honestly, any medication that you take really should be consulted with a doctor or a pharmacist first. The list keeps on changing, and new improved meds are constantly introduced and or improved, that it's virtually impossible to list all of the OTC as well as prescription drugs that should be avoided. If you have a cold for example, I'd just go to the pharmacist, and ask for them to recommend something for you. One general rule however that generally speaking remains true, is the longer acting the drug is, the more risky it's going to be.

I hate to leave you with such a non answer, but it's really what I had to do every-time I picked up something for my wife while she was breastfeeding.
If she had a sinus headache, I'd go out and ask, and same thing true with just about everything in that category.

Hope that this is of some help to you!
Jeff K