The owner of Boots has warned it could close stores after what it described as the retailer's "most difficult quarter" in its history.
Walgreens Boost Alliance said it store closures were an inevitable part of a "significant restructuring". Like-for-like sales in the UK were down 2.3% but Boots in the UK stressed that is maintained its market share.
It said: "We currently do not have a major programme envisaged, but as you'd expect, we always review underperforming stores and seek out opportunities for consolidation."
Chief executive Stefano Pessina said: "We are going to be more aggressive in our response to these rapidly shifting trends."
Among the measures announced, Boots said it will be "optimising its store footprint", as well as increasing its annual cost savings from $1 billion to $1.5bn.