I was on Ketek for 10 months. Within 4 hours of taking my first dose I had a herx but it really did not do much for me at all symptom wise. I got a sore throat that day and had the sore throat the entire time I was on it. I had my liver enzymes tested every 2 weeks and they did go up slightly but not enough to discontinue the medication.
When I went to see Dr. H in NY they immediately took me off the ketek I think mostly because I hadn't had any improvement with it. From what I read it is suppose to be very good for Lyme but most doctors are afraid of it.
I did have to sign a waiver before taking it outlining all the potential problems it could cause. My doctor had told me at the time if I was going to have a reaction I would have it quickly within the first few doses. At the time I was so sick I was willing to try anything.
Hope this imformation helps.