Hair loss is a concern for many people, ranging from daily shedding to noticeable thinning, and the psychological stress it causes should not be underestimated. In recent years, PRP (Platelet-Rich Plasma) injection therapy, as an “autologous regenerative” treatment, has gradually entered the field of hair loss management. Below, we discuss from an evidence-based medicine perspective what it really is, how strong the evidence is, and how it is applied clinically.
PRP stands for Platelet-Rich Plasma. It is a plasma component extracted from the patient’s own blood, which, after centrifugation and concentration, can achieve a platelet concentration three to five times that of whole blood. Platelets contain a large number of growth factors, such as platelet-derived growth factor, vascular endothelial growth factor, and epidermal growth factor, which play a key role in tissue repair and regeneration.
The theoretical basis for injecting PRP into the scalp’s balding areas is that high concentrations of growth factors may activate stem cells around hair follicles, promote the transition of follicles from the telogen phase to the anagen phase, and simultaneously improve local microcirculation while inhibiting inflammatory responses. However, it must be clarified that this mechanism is primarily derived from in vitro experiments and animal studies, and the exact pathway of action in humans has not yet been fully confirmed.
Currently, the most commonly studied use of PRP for hair loss is androgenetic alopecia (i.e., seborrheic alopecia), applicable to both men and women. Preliminary studies also involve alopecia areata and telogen effluvium, but the evidence is more limited. Androgenetic alopecia is characterized by progressive miniaturization of hair follicles, and PRP is thought to potentially slow or partially reverse this process.
So, what is the level of evidence for PRP in treating hair loss? In evidence-based medicine, evidence levels are typically ranked from systematic reviews, randomized controlled trials (RCTs), cohort studies, case-control studies, to case series, and so on. The highest quality evidence currently available comes from several systematic reviews and meta-analyses that pooled data from multiple small-sample RCTs.
Overall, these meta-analyses show that compared to placebo injections or no treatment, PRP injections can lead to statistically significant increases in hair density and hair diameter in the balding areas over the short term (usually 3 to 6 months). However, the magnitude of effect is modest, and individual variability is significant. Additionally, most studies have relatively short follow-up periods (mostly 6 months to 1 year), and high-quality evidence on the long-term efficacy and safety of PRP is lacking.
Therefore, the level of evidence is rated as “moderate” or “insufficient.” Some international guidelines for hair loss treatment list PRP as a “second-line or adjunctive therapy to be considered,” and it is not recommended as a first-line option. Main reasons include significant variability in preparation protocols across studies (centrifugation speed, activation methods, injection intervals are not standardized), a lack of standardized controls, and potential publication bias.
At the clinical application level, PRP injection typically follows this process: First, 10 to 20 milliliters of venous blood are drawn from the patient, centrifuged in a specialized tube to separate the PRP, and then injected directly or after activation (e.g., by adding calcium chloride or thrombin) into the balding areas. Injection methods include intradermal injection or microneedling, with sessions repeated every 4 to 6 weeks, and a typical course consisting of 3 to 6 sessions.
In terms of efficacy: Some patients subjectively report reduced hair shedding and thicker hair after 3 to 4 sessions, and objective measurements have shown increases in hair follicle density ranging from 10% to 30%. However, not everyone responds, and patients with advanced hair loss (where the scalp is smooth and lacks follicles) are essentially unresponsive. Additionally, efficacy may be slightly inferior in women with androgenetic alopecia compared to men.
Adverse effects are generally mild. The most common are temporary pain, redness, swelling, bruising, and slight bleeding at the injection site, which typically resolve within 1 to 2 days. In rare cases, infection, scarring, or hematoma may occur, and strict aseptic techniques can reduce the risk. Since PRP is derived from the patient’s own blood, there is no risk of immune rejection or transmission of infectious diseases, which is a major advantage.
It is particularly important to note that PRP treatment for hair loss in China currently falls under off-label use (i.e., it has not yet received regulatory approval from the drug administration for a specific hair loss indication) and is not covered by medical insurance. Costs are relatively high (ranging from several hundred to several thousand yuan per session) and require multiple maintenance sessions. If treatment is discontinued, results may regress to baseline levels, meaning it is more like a long-term intervention measure.
In summary, PRP injection for hair loss is an evidence-based adjunctive approach with a moderate level of evidence. It cannot replace standard medications such as minoxidil or finasteride, nor hair transplant surgery. For patients with early to moderate androgenetic alopecia who are intolerant to or have poor responses to medication, it may be attempted under a physician’s evaluation. Before choosing this treatment, ensure that the facility has the appropriate qualifications and requires the use of compliant medical-grade centrifugation equipment.
(For reference only, not medical advice.)