PRP for hair loss: what Harvard Health says about the evidence

Scalp injections made from a patient’s own blood may offer some benefit for hereditary hair thinning, according to Harvard Health. However, its overview of platelet-rich plasma, known as PRP, does not establish the procedure as a cure or show that it works across different causes of hair loss.

The article, published on 11 May 2020, remains useful for understanding the treatment’s rationale and limitations. Its age matters: this is an examination of an archived clinical explanation, not news of a fresh trial, regulatory approval or updated recommendation for UK patients.

What happened

Writing for Harvard Health, dermatologists Dr Neera Nathan and Dr Maryanne Makredes Senna assessed where PRP might fit into hair loss care. Their account describes a possible additional treatment for androgenetic alopecia — hereditary pattern hair loss — rather than a replacement for established options.

The authors reported that evidence suggested PRP might work best alongside topical minoxidil, a medicine applied to the scalp, or oral finasteride, which reduces the effects of a hormone involved in male pattern baldness. This does not mean that either medicine, or the combination, is suitable for every patient.

Pattern hair loss can affect men and women, although its appearance often differs. Men commonly notice recession at the front and thinning over the top of the head; women may first see a widening parting. Our guide to male pattern baldness, treatment and when to seek help explains the usual signs in men.

Importantly, the Harvard article does not supply an overall success rate, a dependable estimate of how much hair someone might regain, or a way to predict who will respond. Readers cannot use it to calculate their personal chances of a worthwhile improvement.

Nor is this a report of one experiment with a defined group of participants and a single treatment protocol. It is an expert overview drawing on published evidence. That distinction matters when assessing claims that Harvard has proved a particular clinic’s PRP package works.

The background

PRP begins with a blood sample, usually taken from the arm. A centrifuge, a machine that spins samples rapidly, separates the blood into different components. The clinician collects a platelet-enriched portion of the plasma, the liquid part of blood, for injection into areas of scalp thinning.

Platelets are small blood components best known for helping blood clot. They also release growth factors, proteins involved in signalling between cells during tissue repair. Harvard Health describes platelet concentrations in PRP as generally around five times those in ordinary blood, although preparation methods differ.

The proposed hair-growth mechanism involves dermal papilla cells, a specialised group of cells at the base of a hair follicle. Follicles are the structures in the skin that produce hair. Researchers believe platelet-derived signals may influence these cells, but a plausible biological explanation does not by itself establish a reliable clinical benefit.

PRP is not a hair transplant: no follicles are moved from one part of the scalp to another. It is also distinct from microneedling, which makes tiny punctures in the skin. Although PRP and microneedling can appear together in cosmetic treatments, they are separate procedures, and evidence for one should not automatically be assigned to the other.

Why the diagnosis changes the decision

Hair shedding is a symptom with several possible causes. Telogen effluvium is increased shedding after more hairs than usual enter the resting stage of their growth cycle. Illness, childbirth, substantial physiological stress and some medicines can trigger it. Assessing the trigger may therefore be more useful than immediately choosing a procedure.

Medication history can be particularly relevant when shedding starts after a treatment change. Our explanation of isotretinoin-associated hair loss covers one example. A suspected connection should be discussed with the prescriber rather than used as a reason to stop prescribed medicine without advice.

Alopecia areata is different again: the immune system attacks hair follicles, often causing patches of hair loss. Scarring alopecias involve inflammation that can permanently damage follicles. The Harvard authors found insufficient evidence to draw conclusions about PRP’s effectiveness for these conditions or telogen effluvium; findings in pattern thinning cannot simply be transferred to them.