Can saw palmetto really help combat female hair thinning? If so what are the side effects if I don't continue use?

There is no medical evidence that saw palmetto improves hair growth or stops hair loss. I suggest seeing a hair loss expert to evaluate and go over your condition and provide you information about your best treatment options. There are great non-invasive options like PRP/progesterone and/or hair transplantation. See an expert. Best, Dr. Emer

Saw
palmetto is an OTC medication with properties reported to mildly block
DHT.  There is no evidence that saw
palmetto will help a typical female patterned hair loss.  It can help women who suffer from male
patterned baldness due to excess testosterone in their bodies.

There is no evidence that Saw palmetto will benefit female androgenetic alopecia. I have not been convinced patients achieve benefit who have used it. I do not use it in my practice.