Hi & Welcome. These medications generally do not appear to harm the kidneys however, dosage of Ultram need to be adjusted on the basis of creatinine clearance. 1. Flexeril (Cyclobenzaprine) is a muscle relaxant used together with rest and physical therapy to treat painful spasm of skeletal muscles. It is extensively inactivated and is excreted from the body. It is not known to increase the creatinine level and does not cause any harmful effects on the kidneys 2. Ultram (Tramadol) is an opioid (narcotic) analgesic (pain reliever) that is used to treat moderate to severe pain. It does not increase the creatinine level does not appear to cause any harmful effects on the kidneys. It is also extensively inactivated before its excretion however, in patients with creatinine clearance of less than 30 mL/min, its dosage needs to be reduced. Since you did not mention about the type of mild laxative to over come Ultram induced constipation, laxatives like Senna or Bisacodyl are generally prescribe to treat such cases. They appear to be safe in presence of existing kidney disease. However, I would recommend certain lifestyle changes to prevent constipation like: 1.Increase your daily physical activity level – Daily walk, stretching, light housework. 2. Eating a high fiber diet by eating much more fruits and vegetables. Also, if you are not able to get enough fiber through your diet, a fiber supplement maybe beneficial. 3. Drink much more water and 4. Do not use laxatives or stool softeners for long periods of time. Hope I could answer your queries. Best regards. A feed back is appreciated.