Propecia vs PRP for 50 year old: concerned about the side effects.

The research performed and the anecdotal evidence would suggest that thickness of hair and density can improve with PRP injections.  The number of sessions as well as the quality of PRP obtained will vary considerably physician to physician.

Very few individuals have a dramatic response to Propecia or Rogaine.  Both help to slow down hair loss.  You can think of these agents as anti-aging medicine for your hair.  Hair loss will occur over time no matter what you do.  However, there are many ways you can slow down the hair loss process.  
All hair follicles cycle.  Hairs grow, rest, fallout, and regrow.  Collectively, this is one cycle.  Then, hair follicles repeat the cycle again and again.  In androgenic alopecia, the growth phase shortens and the resting phase lengthens.  This speeds up the rate for each cycle.  When the critical number of cycles is reached, the hair follicles no longer return to the growing phase and nothing we have today will induce the follicles to grow again.  Thus, your goal is to keep the hair follicles growing as long as possible by increasing the duration of the growing phase.  You cannot let them rest.  To achieve this, you should use as many products and treatments as you can to keep the follicles in the growing phase.  These include Propecia, Rogaine, Wnt-Act (a Wnt up regulator), Nizoral shampoo, high quality PRP at least every 8 to 12 months, saw palmetto, and anything else can think of.  Hair cycle shampoo can also help to increase the duration of the growing phase.  
You must think of treating you hair loss as anti-aging medicine for your hair.  If you keep the hair follicles in the growing phase, the will last longer and you will have the enjoyment of hair longer.  
One final note is that the best single product for growing hair that I have seen is topical finasteride that I to in Italy.  It also has minoxidil in it.  Hands down it's the best and it does not have side effects that I know of.  

Prp is effective, but I have a very specific protocol, every 3-4 weeks for 6 months with prp therapy.  I also add in progesterone to speed the healing process.  After that the injections are tailored down.  You should also be on viviscal and other growth promoting ingredients. Best, Dr. Emer

In my opinion, I would advise you not to discontinue the minoxidil. It will lead to a hair shed. Finasteride has been shown to decrease the incidence of prostate cancer approximately 25%. However,when prostate cancer is found, it is in a more advanced stage. You should get a  PSA before treatment and then follow once a year. In addition you should see a urologist once a year. The combination of finasteride and PRP is synergistic. Consider trying the combination and discontinuing the finasteride, should you develop any side effects. Find a PRP expert. Ask to see photos.
PRPHAIRMD.COM 

PRP or Platelet Rich Plasma, has minimal to no known side effects and helps maintain the hair you already have and strengthens thinning hair. You will have to have the procedure done 3 to 4 times a month,to a month and a half apart and then follow up treatments every 4 to 6 months indefinitely. It can be a bit expensive but it is effective. Finasteride is probably less expensive, is definitely effective for men with hair loss, but it’s side effects are increasingly becoming problematic. I have had a few men who have come to me for erectile dysfunction that started soon after they started using propecia and continued long after they stopped using it.