Hello, Cipro and drugs in that class (fluoroquinolones) clearly can cause damage to tendons and muscles. If fact, that class of drugs recently got this warning from the FDA The US Food and Drug Administration (FDA) has stated that the serious adverse effects associated with fluoroquinolones generally outweigh the benefits for patients with uncomplicated acute sinusitis, acute bronchitis, and urinary tract infections who have other treatment options [1]. For patients with these infections, fluoroquinolones should be reserved for those who have no alternative treatment options. This announcement was based on an FDA safety review showing that systemic fluoroquinolone use is associated with disabling and potentially permanent serious side effects, including those involving the tendons, muscles, joints, nerves, and central nervous system. He may need this drug to treat pseudomonas but you needs to let his doctors know immediately that he is having this side effect. Regards