Getty ImagesGuinness pub purchases in the run up to Christmas have been limited by its maker Digeo following “unusual demand” over the past three weeks.
The firm is understood to be operating at 100% production capacity, but still has limited orders in the UK.
The drink is growing in popularity among women and young people, and recent rugby internationals have put pressure on supply.
Diageo has been ramping up its marketing efforts and working with influencers over the past few years to try to raise the profile of Guinness.
The BBC understands Diageo is allocating supplies on a weekly basis to ensure it has enough stock to meet demand over Christmas.
A Diageo spokesman said: “Over the past month we have seen exceptional consumer demand for Guinness in the UK.
“We have maximized supply and are actively working with our customers to manage distribution to the trade as much as possible.”
Gains sales have been bucking market trends recently, according to data from food and beverage industry research firm CGA.
While overall beer consumption fell slightly between July and October, the volume of Guinness consumed from kegs was more than a fifth.
Diageo is pouring money into its St James’s Gate brewery in Dublin, and is also building a new brewery in County Kildare.
It is focusing its marketing efforts on efforts to increase the appeal of Guinness with alliances with Scottish singer Lewis Capaldi and actor Jason Momoa.