Beyond minoxidil and finasteride: what the evidence says about laser, PRP, microneedling, and supplements

Minoxidil and finasteride are the two treatments for pattern hair loss (androgenetic alopecia) that carry U.S. Food and Drug Administration drug approval. Everything else on the shelf and in the clinic sits in a different category: devices cleared for marketing, drugs used off-label, or supplements that the FDA does not review for effectiveness before sale. That does not make the alternatives worthless. It means the evidence behind each one has to be weighed on its own. This piece sorts the common options into what controlled research supports, what rests on thin or mixed data, and what has essentially none.

Low-level laser therapy: real randomized evidence, modest effect

Laser caps, combs, and helmets shine red light (typically around 650 nanometers) on the scalp. They are the most heavily studied non-drug device. A systematic review and meta-analysis of sham-controlled randomized trials found a significant increase in hair density with laser therapy versus a fake device, with a standardized mean difference of 1.32 (95% confidence interval 0.99 to 1.64) (Lasers in Medical Science, Liu et al., 2019). The effect held across comb and helmet designs and in both sexes. Dozens of these devices have moved through the FDA’s 510(k) clearance pathway since a hand-held unit was first cleared in 2007 (Lasers in Medical Science / Dodd et al., 2018). A clearance for marketing is a lower bar than a drug approval, and reviewers have cautioned that marketed claims may outrun the data. The fair reading: laser therapy has genuine controlled evidence, the average benefit is modest, and it is best thought of as an add-on rather than a replacement for approved drugs.

PRP injections: many trials, but shaky pooled quality

Platelet-rich plasma (PRP) involves drawing your blood, spinning it to concentrate platelets, and injecting it into the scalp. It has been tested in a surprising number of randomized trials. A 2024 systematic review pooling 13 RCTs in 609 patients found PRP raised hair density by a mean of 27.55 hairs per square centimeter versus placebo (95% CI 14.04 to 41.06) (An Bras Dermatol, 2024). The catch sits in the fine print: heterogeneity was extreme (I-squared near 96%), and the authors graded the overall certainty as low because trials varied widely in how PRP was prepared, activated, and dosed. Reviews also note that PRP raised hair count versus baseline in some trials, but not consistently versus placebo. PRP is plausible and generally safe, yet there is still no agreed protocol and no high-certainty proof of size of benefit.

Microneedling: strongest as a minoxidil partner

Microneedling rolls or stamps tiny needles into the scalp, and the evidence is clearest when it is paired with minoxidil rather than used alone. A systematic review and meta-analysis of 12 RCTs in 631 patients found microneedling plus minoxidil significantly outperformed minoxidil alone for hair count (standardized mean difference 1.32, 95% CI 0.73 to 1.92) (systematic review, 2024). A representative randomized trial reported markedly higher hair density with the combination than with 5% minoxidil alone (Journal of Cosmetic Dermatology, 2024). Side effects were limited to transient itching and redness. The consistent signal across trials makes microneedling one of the better-supported adjuncts, though the benefit is tied to the drug it is combined with.

Ketoconazole shampoo: promising adjunct, thin trial base

Ketoconazole is an antifungal shampoo used for dandruff, and interest in it for hair loss comes from lab work suggesting it lowers scalp dihydrotestosterone. A systematic review pulled together only seven articles (two animal, five human, 318 people total) and found reports of increased hair shaft diameter, while concluding that randomized trials are needed to confirm any real effect (Dermatologic Therapy, Fields et al., 2020). An older controlled comparison suggested ketoconazole shampoo shifted the anagen-to-telogen ratio in a direction similar to finasteride, but the human evidence base remains small. Treat it as a low-risk possible add-on, not a proven treatment.

Saw palmetto: mostly small combination-product studies

Saw palmetto is a plant extract marketed as a natural DHT blocker. A systematic review identified five RCTs and two cohort studies reporting positive signals, including a roughly 27% improvement in total hair count in some studies, while concluding that robust high-quality data are lacking (Skin Appendage Disorders / Evron et al., 2020). Most of those studies tested saw palmetto inside multi-ingredient formulas, so it is hard to credit the herb specifically. Its 5-alpha-reductase inhibition is real but weaker than finasteride. The summary is uncertainty, not proof.

Biotin: only if you are deficient

Biotin is the supplement most disconnected from its evidence. Overt biotin deficiency can cause hair loss, and correcting a true deficiency reverses it. But in people who are not deficient, and clinically meaningful deficiency is uncommon on a balanced diet, there is no controlled evidence that biotin improves hair growth (Journal of Clinical and Aesthetic Dermatology, 2024). The highest-quality study found no difference from placebo. Dermatology journals have also flagged a safety issue unrelated to hair: biotin can distort common lab tests, including thyroid and troponin assays (Journal of the American Academy of Dermatology, biotin interference reports). Popularity here runs far ahead of the data.

Collagen and marine-protein supplements: brand studies, not disease trials

Collagen by itself has no controlled evidence for pattern hair loss. Marine-protein blends such as the AminoMar complex in Viviscal have small industry-funded RCTs; a 90-day double-blind study in 30 women with thinning hair reported significantly more terminal hairs than placebo (Journal of Clinical and Aesthetic Dermatology, Ablon, 2015). Multi-ingredient products like Nutrafol have a couple of company-sponsored RCTs in women with self-perceived thinning. These are small, often funded by the makers, and typically enroll people with mild thinning rather than diagnosed androgenetic alopecia. The results are not nothing, but they are far weaker than the drug and device evidence.

Rosemary oil: one comparison, no placebo arm

The viral claim traces to a single trial that randomized 100 men to rosemary oil or minoxidil 2% for six months (Panahi et al., Skinmed, 2015). Both groups showed a significant hair-count increase at six months, with no significant difference between them, and scalp itching was reported more with minoxidil. The design has a large hole: there was no placebo group. So the study shows rosemary was not clearly worse than a low dose of minoxidil, not that it beats doing nothing. That is a much smaller claim than social media suggests.

The bottom line on evidence tiers

Grouped by strength of controlled evidence: laser therapy, microneedling-plus-minoxidil, and PRP have real randomized data, though effects are modest and, for PRP, of low certainty. Ketoconazole, saw palmetto, and marine-protein supplements sit on small or combination-product studies. Biotin (absent deficiency), collagen alone, and rosemary-as-a-cure have little to no controlled support for the strong claims made about them.

This article is evidence reporting, not medical advice. Individual causes of hair loss differ, and anyone weighing these options should talk with a licensed dermatologist or clinician before starting or stopping any treatment.

Common questions

Which hair-loss options besides minoxidil and finasteride have the best evidence?

Low-level laser therapy, microneedling combined with minoxidil, and PRP injections have the most randomized trial data. Laser therapy and microneedling-plus-minoxidil show consistent modest benefits in meta-analyses. PRP raises hair density in pooled trials but the evidence is graded low quality because study methods vary so much.

Does biotin help hair growth?

Only if you have a genuine biotin deficiency, which is uncommon in people eating a normal diet. In people who are not deficient, controlled studies show no benefit over placebo for hair growth. Biotin can also interfere with common lab tests, including thyroid and cardiac assays, so it is worth telling your doctor if you take it.

Is the rosemary oil hair growth study reliable?

It is one 2015 trial of 100 men that compared rosemary oil to minoxidil 2% with no placebo group. Both groups improved similarly at six months. Without a placebo arm, it cannot show rosemary beats doing nothing. It only suggests rosemary was not clearly worse than a low dose of minoxidil in that single study.

Does saw palmetto work like finasteride for hair loss?

Saw palmetto does inhibit the enzyme that makes DHT, but more weakly than finasteride, and most studies tested it inside multi-ingredient supplements. A systematic review found some positive signals but concluded high-quality data are lacking, so any effect is uncertain.

Are laser caps and combs FDA approved for hair loss?

They are FDA cleared, not FDA approved. Clearance through the 510(k) pathway lets a device be marketed but is a lower bar than the drug approval minoxidil and finasteride hold. Sham-controlled trials do show a modest hair-density benefit, so laser devices have real evidence, best viewed as an add-on.