Mr Anxiety (your name says it all!),
Plequenil can have a myriad of side effects (as does just about
any drug on the market for
anything.)!!
Although not a common side effect, yes, hair loss (also bleaching of the hair) is listed in the pharmaceutical literature as a possible side effect.

The hair loss should be reversible upon discontinuing the drug.
Definitely speak to you doctor about this.
zuzu xxx