The US central bank said it would extend Operation Twist, a bond-buying program designed to lower long-term rates and stimulate growth, but stopped short of launching a more aggressive programme of buying bonds outright, or QE3.
Sterling was off 0.3 percent at $1.5667, retreating from a one-month high of $1.5778 hit on Wednesday. The euro was down 0.1 percent against sterling at 80.76 pence.
British retail sales, due at 0830 GMT, are expected to have bounced back in May after falls in the previous month, with the consensus forecast for a headline rise of 1.2 percent on the month, after a 2.3 percent decline in April.
"I suspect that you'd really need a much stronger number than the market expectation of 1.2 percent month-on-month - which may not be possible given that fears about Europe and the UK economy are weighing on consumer sentiment - to really see sterling sentiment improving," said Valentin Marinov, currency strategist at Citi.
"Needless to say, a disappointment there will likely add to the headwinds for sterling across the board."