Hi,
Hair loss in a known but not highly common side effect of Evista. If you do a search: "Evista and hair loss" you will find numerous references to this side effect.
This link:
http://www.ehealthme.com/ds/evista/hair+loss
indicates that as of Sep. 15, 2013, 17,635 people were reported to the FDA to have side effects when taking Evista. Among them, 259 people (1.47%) have Hair Loss.
Time on Evista when these people had hair loss:
< 1 month 4.35%
1 - 6 months 4.