Detectives investigating damage to saline bags at Carlisle's Cumberland Infirmary have been called back in amid fresh concerns.
It was feared more bags of fluids had been tampered with at the hospital.
But bosses have confirmed that, following investigation, the new incident is not being treated as "malicious" at this time.
Police were initially called in to the infirmary on January 4 after a number of saline bags were found to have been tampered with.
An incident room was set up and that investigation continues.
It has now emerged that North Cumbria University Hospitals NHS Trust alerted police again on Wednesday night after clinical staff raised fresh concerns.
A Cumbria Police spokesman said: “Detectives have investigated this report and are not treating this as a malicious incident at this time."
A hospital spokeswoman said they continue to work closely with the police.
She added: "We are pleased that our staff are continuing to be so vigilant.”
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here