The woman in her 40s was pushed over and kicked before her bag was stolen at Bladon Estate by two young men and two girls.
The incident happened at around 8.10pm last night (Wednesday January 20).
The woman was walking her dog behind the flats when the attack happened.
Her black rucksack, containing prescription drugs, her purse and a hairbrush, was pulled from her and taken by the gang.
A spokesperson for the police said: “We are appealing for any information on this callous attack.
“We are also concerned should anyone locate the medication that we are contacted straight away. The medication, codeine and pregabalin, could be dangerous if swallowed by anyone it is not prescribed to.”
Anyone with information is asked to call 101, quoting incident Incident 97 of 21 January or email [email protected] using the incident number as the reference.
People can also report anonymously anonymously through Crimestoppers on 0800 555 111 or online at crimestoppers-uk.org