No improvement even after the 2nd PRP session. Will it improve with more sessions or shall I stop?

Thank you for your question. You didn’t submit a photo, and state you had your second PRP session with a third one scheduled after a month, but you feel you are still shedding hair at the same rate as before your first treatment. You’re asking if you should go further with PRP treatment. 
In light of this question without a photo and further medical history, I will give you some guidance based on our experience in our practice with situations similar to yours for people who come to us. A little background: I’m a Board-certified cosmetic surgeon and Fellowship-trained oculofacial plastic and reconstructive surgeon. I have been in practice in Manhattan and Long Island for over 20 years. I’m also the founder of TrichoStem™ Hair Regeneration Centers, a system we developed to help people with male and female pattern hair loss using PRP and Acellular matrix. This is a system we developed starting about 7 years ago, and people come to us from around the world, so your situation is pretty familiar to me.
I think it’s important you have a proper consultation with the doctor who recommended this treatment plan. Your doctor’s experience should be able to guide you with your expectations. PRP, or platelet-rich plasma, is derived from your own blood and is a concentration of wound healing and growth factors that can, among other things, stimulate hair growth. The question is, what is the long-term plan? I’ve seen patients who have come to us usually after they’ve had about 4 sessions of PRP separated by a month apart. For me, it means that PRP is being done in a short-term sense to stimulate growth, but to what end can you continue this, and what happens if you stop? These are the questions that always should be asked. 
Every doctor will bring their experience to the table, but I’m hearing a lot from patients coming to us is a lot of doctors don’t have a lot of experience. Some doctors are offering PRP kind of halfheartedly with limited knowledge or understanding about PRP, but learned that PRP helps hair loss so now they’re doing it - same thing applies to doctors who are offering PRP and ACell. One of the things really important for you to understand is to first ask your doctor what exactly is the game plan, and why are you still having hair shedding.
I’ll share with you our experience with a different approach with a procedure called Hair Regeneration, and the company I started TrichoStem™ Hair Regeneration evolved from that. About 7 years ago, we were doing hair transplants with the intention of helping those hair transplants heal better in improving graft survival and improving the wound healing of the donor area. A very fortunate side-effect was thinning hair became thicker, and this became true months after the transplant, which is important.
Over several years was developed a method of using PRP and Acellular matrix in an algorithm to help androgenetic alopecia, or male and female pattern hair loss. Now we have a protocol where we treat at a single point, then we watch our patients every 3 months. Depending on the type of person we’re treating, we’ll do another treatment at 15 months. Now this protocol and prior protocols have resulted in about a 5-year longevity of the benefit of treatment, meaning: stopping progression, inducing the regrowth of hair that’s not currently growing, inducing the shed of thinning hairs so thicker hairs grow in, and overall improvement in the strength and quality of the hair.
This stem cell technology of Acellular matrix recruits your body’s adult stem cells in a wound healing scenario to duplicate the tissue it is being placed for. For example, if it’s placed in skin, it helps heal with skin; it helps muscle heal with muscle as opposed to scar tissue. The mechanism for the hair treatment remains not fully defined, but I suspect there is a lot of subcellular, cellular, and biochemical interactions resulting in a longevity that doesn’t require constant injection, which is a big deal. For patients who come to us from around the world, it’s impractical for them to even consider coming to us every month, so this protocol and system we developed has worked out very well.
I look at every patient as an individual and their relative situation. For males, I look at their age of onset, the rate of progression, and what I suspect is their relative DHT sensitivity. With women I also look at the different variables. Every patient is still an individual, but this has been our treatment that has worked out very well, and we frequently see people who are fatigued with going monthly for PRP treatment.
This doesn’t mean there’s no benefit to PRP. We use PRP in our practice for a lot of things: acne scars, wrinkles, under eye dark circles, and skin texture improvement. We have helped a lot of people using PRP, and I think it is a remarkable technology. PRP is slowly, or reluctantly, recognized by the dermatology community and other specialists. I think you need to ask this question to your doctor.
We follow our patients very closely. We take photos every 3 months, review their results, and explain what is typically anticipated. We don’t expect after one injection that suddenly, everything gets better immediately. There’s a process where the body responds to our treatment that we have been able to document and help people understand the trajectory of what to expect. Close follow-up is extremely important. I have presented to you some new, hopefully useful ideas to help guide you on how to make your decision moving forward, but I can’t emphasize enough the dialogue with your doctor about what’s going on, and what to anticipate moving forward. I hope that was helpful, I wish you the best of luck, and thank you for your question.

Results vary from patient to patient, and treatments may need to be continued intermittently to maintain improvement. The amount of time receiving therapy will depend on, final goals, amount of hair loss, and patient’s response to therapy. Most patients will begin to see results within 3-6 months

I think it would be worthwhile to add Finasteride and/or Minoxidil to your regimen to help decrease shedding.Please discuss with your physician.