I did not chance it and I started taking homeopathic medicine or natural medicines like tea, honey and lemon for colds. Also you can eat garlic too. "They" have said that some meds are okay to take while nursing.
Most meds are ok, but if you can't get an answer on here (in the future) Dr. Hale's book, Medications and Mothers Milk is a great resource, and you can buy it used from Amazon for super cheap, and also google "lact med".
Sinus medications will diminish your supply a bit, 'cause they're drying. If you have lots it's no big worry, but sometimes kids don't like the more concentrated milk (it tastes saltier)... although some do.