Are there cold medicines that are ok to take when you are on coumadin (warfarin)?

Yes. Yes, for example any variance of mucinex, (guaifenesin) just make sure if there is Acetaminophen in combo total dose of Acetaminophen in 24 hrs is no more than 2 g.
Yes... ...But they are also pretty useless most of the time. If you are taking coumadin, (warfarin) your underlying condition may make you more susceptible to infections, so check with your doctor if you need anything more than a "cold" med.