The dollar sank to a three-year low against a basket of currencies and was at risk of a drop to $1.50 versus the euro.
The dollar slid across the board, with the Australian dollar challenging previous highs to a 29-year peak above $1.0900. Both the euro and sterling scaled 17-month highs.
Analysts said more dollar weakness was likely after the Federal Reserve said overnight that it would end its bond-buying programme in June as planned and appeared in no rush to tighten monetary policy further.
The dollar index has slid nearly 4 percent this month, on track for the biggest monthly decline since Sept. 2010 and bringing it closer to a record low of 70.698 hit in March 2008.


The euro hit a 17-month high above $1.48, its rise having gained steam after triggering stop-loss bids around that level and after breaching resistance around $1.4850.
The dollar gained no traction from a news conference by Federal Reserve Chairman Ben Bernanke on Wednesday where he forecast weaker U.S. growth in the first three months of 2011, though he attributed it to transitory factors. It was the first regularly scheduled briefing by a Fed chief in the central bank's 97-year history.
Sterling also hit a 17-month peak near $1.6750. Possible upside targets include the November 2009 high at $1.6879 and then the August 2009 peak of $1.7044. The 200-week moving average at $1.7005 may also serve as resistance.
The Australian dollar scaled a fresh 29-year high near $1.0950 and was last up 0.8 percent at $1.0943.