What is the best hair serum for promoting hair growth?

Hair Serums for Hair Growth: Evidence-Based Recommendations

There is no high-quality evidence supporting the use of commercially available "hair serums" for promoting hair growth; instead, topical minoxidil (FDA-approved) remains the gold standard topical treatment for androgenetic alopecia, with platelet-rich plasma (PRP) showing promise as an adjunctive therapy.

Why Commercial Hair Serums Lack Strong Evidence

The term "hair serum" typically refers to cosmetic products marketed for hair growth, but these products face critical limitations:

• No FDA requirement for efficacy proof: Hair supplements and cosmetic serums are regulated as foods or cosmetics rather than drugs, meaning manufacturers do not need to demonstrate efficacy or safety before marketing 1

• Limited clinical trial data: Most commercial hair serum ingredients have only in vitro evidence, animal studies, or no clinical trials at all 1

• Proprietary blends obscure evaluation: While one study of Kerascalp serum (containing esculin, ximenynic acid, and lauric acid) showed improvements in anagen:telogen ratio and hair density over 90 days, this was an open-label, single-arm study without placebo control, limiting the strength of conclusions 2

• Another serum study (REVIVV®) containing phytochemicals like EGCG and saw palmetto showed improvements in a real-world setting with 150 participants, but this was also open-label without placebo control, making it susceptible to bias 3

Evidence-Based Alternatives to Hair Serums

First-Line: Topical Minoxidil

Topical minoxidil is the established, FDA-approved treatment for pattern hair loss and should be considered before experimental serums:

• Combined with PRP shows superior results: Studies demonstrate that topical 5% minoxidil combined with intradermal PRP has higher efficacy than topical 5% minoxidil alone in androgenetic alopecia 4

• PRP monotherapy versus minoxidil: Most studies show PRP monotherapy is more effective than minoxidil monotherapy, though minoxidil is better tolerated due to pain from PRP injections 4

• Screen for underlying causes first: Before starting any treatment, check for thyroid dysfunction, iron deficiency, or other medical conditions that may cause hair loss 5

Second-Line: Platelet-Rich Plasma (PRP)

PRP represents the most robust evidence for a "serum-like" treatment that actually works:

• Significant increase in hair density: Numerous clinical trials show significant increases in hair count per cm² after PRP injections compared to controls 4

• Platelet concentration matters: Higher platelet concentrations produce greater effects on hair density, follicle diameter, and terminal hair density 4

• Application method considerations: Microneedling with PRP was found superior to injection technique for anagen phase, telogen phase, and average hair length 4

• Mechanism of action: PRP increases proliferative activity of hair follicle cells and improves hair morphology, with studies showing increased basal keratinocytes and improved epidermal thickness 4

What About Popular Supplement Ingredients?

Biotin supplementation lacks clinical evidence despite widespread popularity:

• No clinical trials exist: To date, there have been no clinical trials investigating biotin supplementation for treatment of any type of alopecia, nor randomized controlled trials studying its effect on hair quality and quantity 6

• Discrepancy between popularity and evidence: A 2024 systematic review found that the highest quality double-blind, placebo-controlled study showed no difference between biotin and placebo groups for hair growth 7

• Not routinely recommended: Because of lack of clinical evidence, biotin use to improve hair quantity or quality is not routinely recommended 6

Zinc supplementation shows mixed results:

• Lower serum levels in alopecia areata: Most studies identify lower serum zinc levels in patients with alopecia areata compared to controls, with levels inversely associated with disease severity 4

• Supplementation evidence is weak: The only double-blind, placebo-controlled trial of 220 mg oral zinc sulfate twice daily for 3 months showed no improvement in alopecia areata despite increased serum zinc levels 4

• Insufficient evidence for routine use: There is a paucity of evidence surrounding zinc supplementation, highlighting the need for additional double-blinded trials 4

Clinical Algorithm for Hair Growth Treatment

For androgenetic alopecia (pattern hair loss):

1. Rule out underlying causes (thyroid, iron deficiency, medications) 5
2. Start topical 5% minoxidil as first-line therapy
3. Consider adding PRP injections for enhanced efficacy, particularly in poor responders to conventional therapy 4
4. Avoid commercial "hair serums" lacking placebo-controlled trial evidence
5. Do not recommend biotin unless documented biotin deficiency exists 6, 7

For alopecia areata (patchy hair loss):

• Limited patchy disease (<1 year duration): Reassurance alone may be appropriate, as spontaneous remission occurs in up to 80% of cases 4
• Intralesional corticosteroids: Most suitable for limited extent patchy hair loss, with 62% achieving full regrowth in one study using monthly triamcinolone acetonide injections 4
• Contact immunotherapy with DPCP: For extensive disease, though this requires specialized protocols 4

Critical Pitfalls to Avoid

• Do not rely on marketing claims: The vast majority of commercial hair serums have no placebo-controlled evidence supporting their efficacy 1

• Beware of combination products: Studies using multiple ingredients simultaneously (zinc + biotin + steroids) make it impossible to determine which component provides benefit 4

• PRP requires proper technique: Ineffectiveness may result from low platelet concentration, low volume injected, or inadequate treatment frequency 4

• Genetics matter: Individual genetic factors are key contributors to hair loss and response to various treatments 4