More than 34 stores in the Lloyds Pharmacy chain were hit by a two-hour work stoppage as around 220 staff belonging to Mandate went on strike over union recognition.
Mandate said the company had refused to engage with the union. Lloyds employs around 930 staff and Mandate said it represented 220 of the company's 800 retail workers and drivers.
However, Lloyds noted that it already negotiates with an in-house Colleague Representative Council and does not need to engage in further negotiations with unions.
The two-hour strike by some retail staff and drivers hit 34 of Lloyds' 88 stores countrywide, but management insisted all stores would remain open.
Mandate said Lloyds would not negotiate with it, despite a Labour Court recommendation urging engagement.
The union is demanding a pay increase and incremental pay scales, a sick pay scheme, security of hours with no zero-hour contracts, and improved annual leave and public holiday entitlements.
The company argued that it had recently agreed pay rises and a new sick leave scheme with the CRC, with further improvements promised.
It categorically denied union claims that it uses zero-hour contracts and said all part-time employees work an average of 25 hours a week, with six weeks advance notice of their working time.
The union argued that the Lloyds offer was inadequate and that the CRC was effectively controlled by management.
Mandate said that if its demands were not met, it would escalate to a three-hour stoppage next Friday.
Meanwhile, in a statement this afternoon Lloyds Pharmacy said discussions with the employee negotiating body are continuing.
The company said it will bring forward proposals, including specifics on pay scales, to a scheduled upcoming meeting with the employee committee.
Lloyds Pharmacy said real progress had been achieved over recent weeks, with increased pay and sick pay agreements.
The firm said it is committed to maintaining that momentum.