Fumaderm side effects - my worst case senario

[OneBigItch]

Hi,

After battling with Psoriasis for many, many years and after trying Acitretin which seemed to make my skin worse, I have finally been put onto Fumaderm which I am going to start taking on Saturday.

Now I am somewhat of a hypercondriac (slight understatement) and so I'm now worrying that when I start taking the medication I am sure to get PML, which I have read is a fatal brain disorder.

I know how rediculous that sounds but I don't normally get regular illnesses, I get the rare ones. I know PLM is a rare side effect but what are the odds of me actually getting it?

Is this something I should be worrying about because it's playing on my mind to the point of, even with my psoriasis as bad as it is, wondering whether to actually take the medication or not.

I'll be happy for you to tell me to stop being silly.