This is no secret. Even the side effect warnings on the box that Nizoral is sold in says that hair shedding is a possible side effect.
However, you have to discriminate between the concept of hair shedding, and hair loss. The addition of many treatments that offer long term improvement in hair counts often times include shedding as a short term side effect. Minoxidil, for example, the hairloss treatment that is the best proven treatment to increase haircount also included hair shedding as a short term side effect.
As for her challenge to 'do a google on Nizoral', I did so and found nothing remarkable to report. Just lots of Nizoral sales websites, and a lot of message board citations stating how Nizoral is a good thing for a hairloss sufferer to include in a regimen. If she has something substantial to say about it, why doesn't 'Sonia' just spit it out and get it on the table rather than make inferences that, frankly, I cannot see any substantiation for.