The barrel was left in the rear yard of the Old Ship pub in Lee-on-the-Solent, Hants, for collection by the brewery because it was a faulty cask.
It had been there for four days and is thought to be unfit to drink.
Police said the thieves who took the chrome cask on Wednesday night are likely to suffer stomach cramps, vomiting and diarrhoea.
Pc Julia Cobb, of Hampshire Constabulary, said: "This beer had been left out in the elements for four days so by the time it was stolen it would not have been fit to drink.
"The yeast would have started to ferment and it's possible that flies would have collected in the barrel.
"It is possible that whoever stole the beer has already started drinking it and will already be feeling quite ill."
^ Back to top | BBC Sport Home | BBC Homepage | Contact us | Help | ©