Hopefully sharing my experience w/ Vitamin B5 will help others. 

I have taken low dose accutane for years. I wanted to take less of it so I started taking 6 grams of Vitamin B5 daily in the Summer of 2017. At first I thought it was helping my hair to grow thicker. I usually have sort of sparse temples and they seemed to thicken up. It was also great for my skin. My skin was less oily and more even in tone. In September 2018 the brand of accutane I was taking was discontinued. I was upset because some other brands have caused hair loss for me in the past. Reluctantly I started another brand. In October 2018 my hair started falling out rapidly. I would brush my hair and huge amounts would be in the brush. Every time I touched my hair it would fall out. In November 2018 I decided to take a break from accutane altogether. My hair continued to fall out, but I just assumed I had to wait it out. My hair continued to fall out and at the beginning of 2019 it was bad enough that I decided to just shave my head and start wearing wigs. I also lost most of my body hair including my eyelashes and eyebrows. I went to my derm and had a scalp biopsy which showed I had telogen effluvium. However, she thought it was too severe to be caused by the super low dose of accutane I was taking. So about 4 wks ago I decided to restart the low dose accutane and stop the Vitamin B5. Up until this point I thought there was no way it could have been the B5 because I had taken it for over a year without any hair loss. Within a week of stopping the B5 my hair started to grow back. It's now 4 wks since I stopped and my eyelashes and eyebrows are back, I have about a half inch of new head hair, and my body hair is coming back. My hair is still thin, but it's starting to get thicker.

Below are some photos of my hair journey. The first photo is before the hair loss. The second photo is right before I shaved my head in early 2019. The third photo is after shaving my head (my brows were tinted here, I hardly had any). The last photo is today after 1 month of regrowth.

I am sharing my story so others know that this is a possibility when taking Vitamin B5. It helped my skin so much, but it destroyed my hair. I'm really hoping it will go back to what it was before. If anyone is considering taking Vitamin B5 please think very long and hard about it.