@Kamta Kesharwani in cmos processes there is usually no current rating set for small devices. There are voltage ratings. so 01v8 transistors can handle voltages on gate / drain / source lower or equal to 1.8V with some tolerance, so i would say never above 2.0V. Of course operating a short channel device at full bias continuously (high Vgs, high vds) will make its lifetime shorter, due to aging effects (threshold shift, hot electron injection and more).