This antibiotic does seem to have an unasluuly high level of potential side effects. I (we) have to assume your physician has taken this into account when evaluating benefit to risk. I am unaware of the mechanism behind the tendon problem. I can only offer the general advice of taking a high potency probiotic blend, a broad spectrum multivitamin/multimineral, a phyto antioxidant blend (such as PhytoTech Antiox Phyto Complex, and, in this case I would add alpha-lipoic acid, 500 mg twice a day. I also see a recommendation to take supplemental vitamin K, as Levofloxacin may cause a depletion of this vitamin (many antibiotics interfere with the normal production of vitamin K by the microbial population in our gut). I also see caution statements advising against taking extra iron, magnesium and caffeine while on this drug. Continue taking the probiotics, vitamins, antioxidants and alpha-lipoic acid well after you stop the antibiotic.As an afterthought, I might suggest you add coQ10 as well ubiquinol, 100 mg twice a day.Don Goldberg