Sarah Papachristophorou admitted supplying substances to the victim, 77, and stealing up to Â£1,000 from him.
The 47-year-old, who worked as a nurse for more than 20 years, was sacked from her job at Birmingham's Queen Elizabeth Hospital following the allegations.
She was caught when the victim's relatives set up a secret camera.
CCTV showing her taking cash was played at her Birmingham Crown Court sentencing.
The former health worker had also pleaded guilty to supplying the man, who was a family friend, with zopiclone, tramadol and diazepam.
She had taken the class C drugs from her work, which the sentencing judge described as "a gross breach of ethics".
Papachristophorou's barrister Daniel Church asked for a suspended jail term, adding the former nurse, of Four Oaks, Sutton Coldfield, had shown genuine remorse.
But Judge Philip Parker QC said the aggravating features of the case were "odious and despicable" and jailed the married mother of two for 12 months.
A spokesman for the University Hospitals Birmingham NHS Foundation Trust said Papachristophorou no longer worked for the organisation, having been dismissed on 10 May.

Nicholas Briggs, 28, went missing from HMP Leyhill in South Gloucestershire last Thursday.
He is serving an 18-month sentence for domestic assault and was arrested by Gwent Police on Sunday night.
A second inmate, Anthony McCormick, 52, who absconded at the same time, and who was handed a life sentence in 1998 after being convicted of rape, handed himself into police on Friday.

Schools and offices in northern cities are expected to close on Friday afternoon as the storm nears.
The typhoon was 450 km (280 miles) southeast of Yilan county on Friday morning, Taiwan's weather bureau said.
In 2009, Taiwan was hit by Typhoon Morakot, which left hundreds dead in floods and mudslides.
Typhoon Soulik, which was earlier classed as a "super typhoon", weakened overnight and has been downgraded to a medium-force typhoon.
However, it still had wind speeds of around 173 km/hour (100 mph) on Friday morning.
It is expected to hit north and northeast Taiwan on Friday, before moving onto mainland China's eastern provinces on Saturday.
Hundreds of soldiers are on stand-by for emergency response operations and 102 military camps have been prepared as emergency shelters, the Central Emergency Operations Center said.
In a statement, the centre also warned that some areas of Taiwan were prone to landslides.
"The central region of Taiwan has experienced two earthquakes with magnitude six or above on 27 March and 2 June, [and] loose soil after seismic activities are potential disaster areas under heavy rainfall," it said.
It advised that fishing boats return to the shore before the typhoon hit, and asked members of the public to avoid mountain and coastal areas.
More than 2,000 tourists were evacuated from Taiwan's Green Island, near the city of Taitung, on Thursday as a precaution.
Some flights to Taiwan have been disrupted, with both Cathay Pacific and China Airlines announcing cancellations or planned cancellations.
Typhoon Soulik is expected to arrive in mainland China's eastern provinces of Fujian and Zhejiang on Saturday.
Local authorities have been asked to implement emergency response plans, China's state-run news agency Xinhua reported.
Typhoons are common during the summer in parts of East Asia, where the warm moist air and low pressure conditions enable tropical cyclones to form.
An NHS hospital nurse who supplied a man with prescription drugs taken from her workplace has been jailed for what a judge called "despicable" crimes.
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A second inmate who absconded from an open prison has been arrested.
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Taiwan is braced for the arrival of Typhoon Soulik, a tropical hurricane expected to bring strong winds and torrential rain to the island.