<s>[INST] Hi. We have a 4 week old baby boy with a dilated renal pelvis . We give him antibiotics - Trimethoprim - everyday for this. Recently he seems to be suffering from trapped wind a lot and we were going to give him some gripe water but when we looked at the packet it said to avoid using where impaired kidney function exists. Please advise. Thank you [/INST] Hi and welcome to Chat Doctor. I don't see why are you giving him antibiotics if he doesn't have reinfection. But ok. Dilated renal pelvis isn't uncommon and it usually doesn't cause permanent problems. It is questionable does he have impaired renal function because dilated pelvis doesn't mean that his renal function is affected. It should be evaluated by measuring urea and creatinine. If this is normal you can give gripe water. Wish you good health. </s>