Could Saw Palmetto decrease the effectiveness of Finasteride?

There  are no published studies showing that saw palmetto has any effect. Finasteride, however, is very effective for male pattern hair loss. If one was interested in improving the results, I would add PRP. Find a hair loss expertPRPHAIRMD.COM 

No, there is no medical evidence that Saw Palmetto affects hair loss or growth. 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 that work well with Finasteride. Hair transplant is an alternative. See an expert. Best, Dr. Emer

Saw palmetto has been well tested as a treatment for benign prostatic hypertrophy and there is sufficient evidence of its use as a prostate treatment. The Mayo Clinic gives saw palmetto an "A" rating for prostate issues, which means there is "strong scientific evidence for this use."The two approved uses for finasteride are to treat enlarged prostates and hair loss. The assumption is if saw palmetto works as a prostate treatment it should also work as a hair loss treatment, but this has not been proven sufficiently and the Mayo Clinic gives saw palmetto a "C" rating as a hair loss treatment, stating there is "unclear scientific evidence for this use." There is no evidence that saw palmetto decreases the effectiveness of finasteride.

I have not heard of any studies directly related to the combination use of finasteride and saw palmetto. However there are many people who do opt for the usage of saw palmetto instead of the finasteride.

Although we don't know exactly how saw palmetto (a.k.a. Serenoa Repens) works, it is assumed to either inhibit DHT, similar to finasteride, or to block alpha-adrenergic receptors, like tamsulosin. Both of these types of medications are used to treat benign prostatic hypertrophy but finasteride also helps male pattern hair loss.  There are small studies to support saw palmetto in hair loss and while there should not be any problem taking them both, I typically recommend patients use something like minoxidil, LLLT, or PRP in order to encourage hair growth by a different mechanism while using finasteride.Here are 2 nice articles on the action of Saw Palmetto:  1. Pharmacological effects of saw palmetto extract in the lower urinary tract Acta Pharmacol Sin. 2009 Mar; 30(3): 271–281. 2. Rossi A, et.al. Comparitive effectivenss of finasteride vs. serenoa repens in male androgenetic alopecia: a two-year study. Int J Immunopathol Pharmacol. 2012 Oct-Dec;25(4):1167-73.

Congratulations on doing something to prevent your hair loss.   Doing nothing is definitely not going to work.  Well done also on choosing a non-surgical method, as hair transplants have their place, but generally as a last resort treatment option.  There are now available better treatments than Finasteride and Saw Palmetto or Minoxidil available.  I would recommend seeing a hair regrowth specialist as the next step in your battle against hair loss noting that the treatment you choose should both Stop your hair loss and stimulate hair regrowth together to be most effective.

This is a very ineffective medication in the treatment of balding and prostate problems. I don't believe that there is not interaction with finasteride