It's no guarantee that your hair will thin or your hair will recede. It is possible though. Lots of people go on accutane and don't experience that side effect. I think it's like 8% of people experience that according to me dermatologist. I think it's alittle higher if you have ever read the negative side effect posting before. Seems like lots of people there had that problem. But yes it could do both or one or none of what you mentioned. That's the risks involved and you need to weigh them all. If accutane means thinning hair is your acne worse or would thinning hair be worse? All up to you.
I was on accutane for a 7th month course started at 40 and ended up at 60 mg a day. I didn't experience hair issues. Until after my course was over then all of a sudden I was loosing a lot of hair in the shower or bath tub, it wasn't ever noticeable even to me though. I just knew what was in my shower drain. Which was a lot. I was really scared but lucky for me it stopped and my hair is thickening back out again 8 months later. Although I did have side effects all the regular ones like really dry skin and chapped lips beyond belief but iomhad bad ones to. Like swollen joints in my ankles and knees if I used them. Like climbing in and out of a boat trailer would bother my knees to the point I wouldn't be able to do much for a week after that. I also had lower back issues all the time where my back would just ache for no reason, this medication really does a number on people where you can tell 80 years old some days. I mean bare in mind accutane is a form of chemotherapy which can cause hair loss in some patients. So it makes perfects sense that hair might thin or fall out. If you notice anything stop taking the medication ASAP