Hi Nicole, I’ve never heard of this reaction to mullein. I’m going to ask my colleague Benna about it and see if she has any ideas. For now, stop using it of course. Can you let me know what your intention was with using it? If you provide a bit of information about which herbal actions/benefits you were looking to get from it, I will be able to help you find alternative herbs to use. Let me know! 🙂