As such depression
it self is a big factor for low sex drive and the medication used for depression are also causing this problem.
Common medication used for treatment of depression like SSRTI (selective serotonine Reuptake Inhibitors) commonly cause this problem. Now it is important that if depression already have supressed the drive and you are prescribed a drug which further supress this than it is problem.
So if this is happening after starting medication, than consult your doctor to change the medication to something else.
Thanks and take care.