I have taken Eyebright orally, though not consistently and probably not the best product (I have the Christopher product and I am told that the Shulze formula is better). What I can tell you is that I started using it externally yesterday after getting a good eyecup to use for eyewash solutions. The instructions said use 1 to 5 drops. In typical gung ho style I used 5 drops combined with colloidal silver. It burned like the dickens! And colloidal silver has never burned whatsoever, just the opposite. No doubt the pepper portion and perhaps other ingredients in the eyebright were the source of the burninig. Perhaps I will become more accustomed in time, as was the case with oral cayenne tincture (Uny makes a great one). Or maybe I should work my way up to the 5 drops. But it definitely does burn!