I just started accutane. I have really bad constipation I think its unrelated to accutane. Is it okay to use a laxative or fleet enema (sodium bisphosphate) with this drug?

Yes. You can use a laxative once in a while but concentrate on eating healthy with enough fiber and more fruits and vegetables to avoid medications. If chronically constipated you may need doctors advice of how to tackle it with a stool softener which would be safer. .