Alli is not associated with causing hair loss, but that being said, rapid weight loss and diet can trigger hair loss. Hair processing is a factor in itself. There are so many factors that can cause hair loss, it would be difficult to pinpoint it to just one. More important is its onset and pattern, patchy spots or gradual as well as a family history. If this still continues you should check it out with a physician.
There is no problem with increased "hair" vitamin supplementation as they are water soluble.
Sophia De Monte RPh