How common is hair loss/thinning on accutane? can something as low as 10mg or 20mg cause a significant deal of hair loss?

Hair loss: Apparently hair loss is a known side effect of isotretinoin. See http://www.dermnetnz.org/treatments/isotretinoin.html for more details. Tell prescribing physician about side effects & concerns. You'll need to decide which is more problematic for you. In theory, hair loss should be temporary and resolve after finishing your isotretinoin regimen. Don't forget there're other causes of hair loss.