Tylenol is fine to take while being on Coumadin. There is some new evidence that large amounts of Tylenol taken on a daily basis may have a small effect on Coumadin. Some cough and cold preparations can also effect Coumadin levels. Herbs and vitamins can also play a role in Coumadin therapy. A dose of vitamin E above 400IU does have an effect on thinning the blood.
Many herbs also can increase the chance of bleeding.
Again, consult with a doctor or pharmacist before taking any new herbs or vitamins. Contrary to popular belief, herbs can be dangerous and should be treated as seriously as prescription medications. There are hundreds of prescription medications that can effect your coumadin levels. Antibiotics are one group of medicines that often will increase the thinness of blood. Since many people see multiple doctors, it is very important to let every physician a patient sees know that they are taking Coumadin.