I took it and am glad I did. I was on it for around 9 months and the middle months were particularly tough. I can't say it affected my running though...I didn't notice anything unusual and got some decent training in. The side effects (dryness, nosebleeds, etc.) suck but they are worth it in my opinion.
I am 45 yo now and took Accutane in my early 20s. I think it was when it first came out, so there wasn't much info on the side effects. The ONLY side effects I had were extremely dry skin and lips. Lotion and Karmex (lots of Karmex) did the trick for me. I also had a few nose bleeds. I was in heavy training at a D1 school and noticed no soreness or fatigue (beyond the usual amounts anyway from 80 mile weeks and intervals). And I ran PRs while on the medication. It worked wonders and is one of the best things I did, and I never had acne after the course of the treatment. I also see nobody mentioned the number 1 side effect of Accutane - I got laid A LOT. And frankly, I remember the hot chicks more fondly than those PRs !
I took it for 5 months a number of years ago and wished to hell I had done it years earlier. Only side-effects noticed were mild drying of the skin on the face, was no big deal. My teenage daughter took it a couple of years ago and had no ill effects. I think as long as you are taking it under a dermatologist`s supervision you should be fine, I remember that they checked my liver enzymes before going on it to make sure there wouldn`t be a problem that way.
Well I just finished accutane and it works really good! You shouldn't worry about the side effects. Drink lots and I mean LOTS of liquids so the medicine can come out and won't harm you. I didn't listen to my parents about drinking liquid, so here I am in bed with fatigue. But please drink lots of liquids and nothing should happen.