New York's main contract, West Texas Intermediate for May delivery, tumbled 33 cents to USD 98.57 a barrel and Brent crude dipped 18 cents to USD 106.27.
The dollar surged on Wednesday after Janet Yellen said a rate rise could come "around six months" after the Fed's stimulus programme ends. Economists took that to mean an increase in borrowing costs in the first half of 2015, against previous forecasts of a hike in the latter part of the year.
"US dollar strength was the main weight on the West Texas benchmark as markets extended the reaction to (the) Fed announcement," ANZ bank said, according to Dow Jones Newswires.
Traders are also closely monitoring events in Eastern Europe after Russia absorbed the Crimean peninsula following a controversial referendum slammed as illegal by the West.
Russia provides about a quarter of Europe's natural gas supplies, with about 80 per cent of those exports travelling through pipelines in Ukraine, analysts say.
Traders fear that an escalation of the crisis would disrupt those supplies.
