A report says healthcare at Edinburgh Prison is good in general but limited staff numbers have been leading to delays for prisoners accessing some services.
Chief Inspector of Prisons for Scotland David Strang said NHS Lothian should carry out a review, with emphasis on mental health and addiction provisions, "as a matter of urgency".
It is one of 69 recommendations in a report which describes the jail as generally well-run and highlights 18 areas of good practice.
The inspector said: "Prisoners requiring addictions and mental health interventions can experience delays.
"There are concerns regarding the high levels of staff turnover especially among the mental health and addictions nurses. NHS Lothian recognises these issues and is attempting to improve matters."
One woman prisoner who had been referred to an addictions nurse in June had still not been assessed in September, he said.
HMP Edinburgh, in the city's Saughton, houses male and female prisoners, long-term, short-term and sexual offenders, and people still awaiting trial. It holds 907 prisoners, exceeding its 870 design capacity.
Alex McMahon, director of strategic planning, performance reporting and information at NHS Lothian, said: "We note the recommendations and have already addressed a number of these as part of an ongoing action plan."