Rebecca Horton, who worked as a dispenser, stole painkillers and sleeping tablets from the Millview Medical Centre in Heckington for two years before she attracted suspicion.
Horton, 31, of Freeston Road, Heckington, admitted six charges of theft by an employee and a further charge of false accounting.
She was given an eight month jail sentence suspended for 18 months with 20 rehabilitation activity requirement days.
Andrew Scott, prosecuting, said the thefts came to light in August 2019 when discrepancies were discovered in the dispensary’s stock of the sleeping tablet Zoplicone.
“Susan Lampkin, the senior dispenser, found five boxes of Zoplicone in an unlocked cupboard. They should have been stored in a locked drawer.
“She thought the defendant had placed the drugs in the cupboard by mistake. The following day she noticed that the boxes had not been scanned into the records and when she checked the cupboard they were not there. The boxes had been taken without any record made.
“Checks were carried out and huge discrepancies were found between the number of boxes of Zoplicone that had been scanned into the records and the number that had been ordered.”
NHS England carried out an investigation which revealed drugs that were ordered were not always scanned in.
They also found that on a number of occasions Zoplicone was falsely recorded on patients’ records as being dispensed to them, but then deleted.
Lincolnshire Police were called in and their investigations led to the discovery that stocks of the painkillers Oramorph, a liquid form of morphine, and Fentanyl patches were also missing.
Mr Scott: said “Between August 2017 and August 2019 a total of 5,250 Zoplicone tablets were unaccounted for.”
A further 168 bottles of Oramorph and 60 packs of Fentanyl patches were also unaccounted for.
The total value of the drugs stolen was £1,852.
The investigations led the dispensary to be down-graded by the Care Quality Commission to “requiring improvement”.
Horton denied any responsibility for the missing drugs when she was initially interviewed by police but later confessed, the court heard.
Mr Scott said: “She stated that all the drugs were for herself and she said she had not supplied them to anybody else.
“She said she had fractured her knee and it took the doctors six months to diagnose the problem. Throughout that time she was in severe pain and said she used the drugs to self medicate.”
Judge Catarina Sjolin Knight told her: “These are serious drugs.
“A high degree of trust was placed in you and you breached that trust.
“There was some sophistication in the way you took the drugs.”
Mark Watson, in mitigation, said that Horton was not a pharmacist and was effectively counter staff, sometimes working on her own.
He said she initially started taking the Zoplicone as she had difficulty sleeping. Later when she suffered her knee injury she took the painkillers and became increasingly addicted to the drugs.
Mr Watson told the court that Horton lost her job and has since retrained to work in a different sector.