Health - Codeine and Kidneys

[redriver]

I apologise if this query should have gone in an existing thread, I couldn’t find one I deemed suitable.
SWIM was wondering if Codeine is particularly harmful to their kidneys. This interests them as they only have one and would like to take care of it. Their lifestyle is exactly the same as someone with both kidneys and they haven’t received any medical advice to treat their body differently to someone with two kidneys.
They have done a trial run with 64mg Codeine which was CWE’d from 8mg Codeine 500mg Paracetamol to check for allergies etc and felt mildly content. They thought it might be a good idea to ask before increasing the dose.