But the watchdog ruled that the label of the beer – officially Britain’s strongest at 18.2% abv – didn’t place undue emphasis on its alcoholic strength.
It also rejected complaints that the phrase “intergalactic fantasy” on the label was an allusion to illegal drugs.
Brewdog was found in breach of the Portman code of practice on marketing because of wording on the label which stated: “Everything in moderation, including moderation itself. What logically follows is that you must, from time [to time] have excess. This beer is for those times.”
Complaints were received from Alcohol Focus Scotland and a member of the public.
Portman said Brewdog had failed to respond to the complaints.
Chief executive David Poley said: “It’s obviously unwise for any company to urge consumers to drink to excess.
“We won’t allow any irresponsible marketing whether it’s for a big brand or a niche product.
“That’s why we’re taking action to restrict future sales of its beer.”