Yeah, I just use a liquid laundry detergent for sensitive skin, Amolin or something... I use liquid detergents for all our laundry except hubby's work clothes because I once used a brand that left big white powdery streaks all over my black clothes, the liquid stuff dissolves so much easier and can still be used for soaking etc, so I haven't looked back.
There are plenty in your local supermarket so you can compare brands as far as cost, environmentally-conscious etc and make your own decision, and if bubs has a reaction to one just switch brands and you should be right!

My mum washed all DD's newborn stuff before she was born (we got lots of hand-me-downs from friends) in just Napisan, so there's another option if you don't want to be buying two or three different laundry things just for bubs.