The rupee today lost 18 paise to 54.90 in early trade on the Interbank Foreign Exchange due to renewed dollar demand from importers and appreciation of the US currency overseas. Forex dealers said a weak opening in the domestic stock market also put pressure on the local unit.The domestic currency had gained 20 paise, the biggest gain in a week, to close at 54.72 yesterday amid fresh dollar selling by exporters and some banks.