@Nippy , there's been a couple of the Disease Modifying Therapies (DMTs) that have caused hair loss/thinning. Usually, it's a short term side-effect, which recovers well. Use the Forum Search (magnifying glass, top right) and search for Hair Loss to locate previous conversations on this subject..

I have been on plegridy for just over a year and I have noticed definite hair thinning 😔 I'm quite self conscious about it but people tell me that they can't notice it. I take biotin every day to try and help but I haven't noticed that much difference since taking it (but haven't stopped in case it gets worse!).