A man has been arrested and charged after he allegedly spiked a female colleague's drink while they were at work in Sydney's south east.

On "a number of occasions" at work in Kensington, the 26-year-old started to feel ill and believed she had been drugged, she told police.

She suspected her 33-year-old male colleague of putting drugs into her drink, and reported him at Maroubra Police Station on Wednesday.

Officers launched an investigation.

In their inquiries, police obtained closed circuit television (CCTV) footage that allegedly showed the man pouring a liquid into the woman's drink.

He was arrested at his home in Maroubra at 11am on Thursday and charged with tampering with evidence and using poison to injure or cause distress or pain.

Police refused the man bail and he faced court on Friday, where bail was granted.

He will appear in court again on May 24.