In my experience, PRP and PRF have the potential to make a significant difference in changing the APPEARANCE of scars, even those which are a result of suboptimal healing. However, it sounds like you are having issues with scar tissue that are not entirely from its appearance. The itching and pain may or may not improve with PRP treatment, depending on what is the root cause of the issue. Also, what do you mean when you say "It also tightens them."? Clarification on what exactly you mean here could make it easier to provide an explanation. Lastly, it's difficult to make a determination purely based on your description. Most "labiaplasty procedures" refer to the removal of unwanted tissue of the labia minora. If your surgery included anything else, it would affect my recommendations. Also, what were the results of the infection? Did you undergo repeat surgery or other procedure for an abscess, etc.? Was the infection local or did it spread? What tissue was infected? These are just a few questions that need to be answered before a thoughtful response can be provided. The pain and/or itchiness may represent a different medical issue that needs to be addressed entirely. I would suggest first scheduling an appointment with another physician who is intimately familiar with labiaplasty procedures.
Antidepressants, generally speaking, are not a known contraindication for PRP/PRF treatments. The most common medications physicians ask patients to stop taking immediately before and after PRP/PRF procedures are typically those that affect inflammatory processes. For example, NSAIDs (non-steroidal anti-inflammatory drugs) are a common one. However, you should let the physician you expect to perform the procedure be aware of any medications you are currently taking. That physician will review your medication list to ensure your procedure is done safely.
1. For injections, I would recommend considering a second generation platelet concentrate, such as platelet rich fibrin (PRF) - specifically, liquid PRF. Some studies have shown a higher increase in growth factor release in PRF versus PRP for a longer time period. PRF is very similar to PRP, there are just some small, but important, modifications to the processing procedure. 2. When you say "laxity", are you actually looking for a lifting effect without surgery? If you are, depending on the area of the face, doing a thread lift may offer better results. It also depends on what specifically you are trying to address. Ultimately, PRP injections with PRP microneedling is going to offer better results than either procedure alone. Also, rather than doing them months apart, you may want to consider doing a set of monthly treatments for 3 or 4 months.