Assuming you are using a clinically proven treatment, shedding is a sign that the treatment is working. This is not true if you are using a treatment that you just heard about on the internet, or in an infommercial. The only clinically proven treatments on the market are Propecia, Rogaine, Lasercomb, Tricomin, Revivogen, Nizoral, Folligen, and Crinagen. The rest fall into a gray area of "unknown".

Legitimate treatments will cause a change in the hair cycle which results in affected hairs being ejected to make room for new hairs. Thus you may see a temporary wave of increased loss. It's only an apparent increase in actual loss, however, as this falling hair had stopped its growth cycle many weeks earlier and was just waiting to drop out.

Increased fallout of this sort should normalize within a few weeks. If it continues over a prolonged period of time (a few months) it may be that the treatment is contraindicated. Note that some do not notice any increased shedding with various treatments. Increased shedding is most often a positive sign, but its absence is not a negative sign.

Note also that hair fallout is not perfectly uniform throughout the year, so sometimes increased or decreased shedding is simply coincidental with normal hair cycles. Also bear in mind that it is perfectly normal to lose over 100 hairs every day, even if you are not dealing with hair loss. The problem with pattern loss is primarily one of having insufficient regrowth. You can read more about shedding in our article: Shedding, the Four Letter Word of Hair Loss Treatment.