Does Biotin Actually Grow Lashes? What the Science Says

Biotin is on the label of nearly every lash serum on the market. It's also in supplements, hair vitamins, and "growth gummies" sold to anyone trying to get longer hair, stronger nails, or fuller lashes. But does it actually work? The science is much weaker than the marketing suggests.

What Biotin Is

Biotin (also called Vitamin B7 or Vitamin H) is a water-soluble B vitamin. Your body uses it to convert food into energy and to support keratin production — the protein that makes up your hair, skin, and nails.

The logic of the marketing is simple: lashes are made of keratin, biotin helps build keratin, therefore biotin grows lashes. The problem is that this logic skips a critical question: does your body actually need more biotin?

The Studies on Biotin and Hair Growth

Most peer-reviewed research on biotin and hair growth points to one consistent finding: biotin works only when you're deficient.

A 2017 review published in Skin Appendage Disorders looked at 18 studies on biotin supplementation. The reviewers concluded that all positive results came from people with documented biotin deficiency or specific underlying conditions (like brittle nail syndrome). For people with normal biotin levels — which is the vast majority of adults in developed countries — supplementation produced no measurable improvement in hair growth.

Biotin deficiency is rare. Your body needs only about 30 micrograms per day, and biotin is present in eggs, nuts, seeds, salmon, sweet potatoes, and many other common foods. Unless you have a genetic condition, severe malnutrition, or take certain medications that block biotin absorption, you're not deficient.

Why Lash Serums Still Use It

If biotin doesn't help most people grow lashes, why is it in every formula?

It's cheap. Biotin costs almost nothing to add. Brands can list it prominently as an "active ingredient" without raising production costs.

It's recognized. Consumers have heard of biotin for years. Including it makes a serum feel familiar and legitimate, even if it's not doing much.

It supports the marketing story. "Contains biotin for hair growth" sounds compelling on a product page even when the underlying biology doesn't support that claim for the average customer.

It's safe. Biotin doesn't cause harm in normal amounts. So even if it's not effective, it's not a liability. That makes it an easy ingredient to include for marketing purposes.

Topical Biotin vs Oral Biotin

There's another wrinkle: oral biotin (in pills) and topical biotin (in serums) work differently — and the topical version has even less evidence.

Most biotin research is on oral supplementation. The studies that exist on topical biotin applied directly to skin or hair show minimal absorption. Biotin is a relatively large molecule, and the skin barrier doesn't let much of it through to where it would need to act on follicles.

A lash serum with biotin listed in the ingredients is delivering an even smaller amount of an ingredient that already had questionable evidence in oral form. The math gets less and less convincing the closer you look.

What Actually Works for Lash Growth

If not biotin, then what? The ingredients with stronger peer-reviewed evidence for topical lash growth fall into three categories:

Peptides. Specific peptides like myristoyl pentapeptide-17 and biotinoyl tripeptide-1 (different from plain biotin — this is biotin attached to a peptide carrier) have published research showing they can stimulate keratinocyte production and extend the growth phase of the lash cycle. More on peptide research here.

Growth factors. EGF (Epidermal Growth Factor) has decades of research in wound healing and is increasingly studied for hair follicle effects. PDRN (Polydeoxyribonucleotide) has strong Korean dermatology research backing it for cellular regeneration.

Prostaglandin analogs. The most clinically-proven option (FDA-approved for Latisse), but with documented side effects like eye irritation and potential iris darkening.

Notice biotin doesn't appear in this list. That's not because it's ignored — it's because the evidence isn't there.

How to Read a Lash Serum Label

Next time you're checking ingredients on a lash serum, ask yourself:

Is biotin in the top 5 ingredients? If yes, the brand is leaning heavily on a weak-evidence ingredient. Look at what else is in the formula.

Are there real peptides higher in the list? Names ending in "-peptide" (especially copper tripeptide, palmitoyl pentapeptide, biotinoyl tripeptide) signal real bioactive content.

Are there growth factors or PDRN? These have stronger research backing than biotin alone.

Is biotin the headline ingredient? If marketing copy puts biotin front and center, the brand may be hoping you don't look closer at what else is (or isn't) in the formula.

The Bottom Line

Biotin isn't bad. It's just not the lash growth solution it's marketed as. For most people, taking biotin supplements or applying biotin-based serums won't make a noticeable difference because their biotin levels are already sufficient.

If you want lash growth that's backed by stronger science, look for serums built around peptides, growth factors, or PDRN. Biotin can be a small supporting ingredient, but it shouldn't be the main reason you choose a product.

Frequently Asked Questions

Does taking biotin grow eyelashes?
Only if you're biotin-deficient. For people with normal biotin levels (the vast majority of adults), studies show biotin supplementation produces no measurable improvement in hair, nail, or lash growth. A balanced diet typically provides all the biotin you need.

How much biotin do I need per day?
The recommended daily intake is about 30 micrograms for adults. Most people get more than enough through normal eating — eggs, nuts, seeds, salmon, and sweet potatoes are all good sources.

Are biotin lash serums a scam?
Not exactly a scam — biotin is safe and inexpensive — but the evidence that topical biotin grows lashes is weak. If a serum's main "active ingredient" is biotin, you're likely paying for marketing more than for proven biology.

What's the difference between biotin and biotinoyl tripeptide-1?
They're different ingredients. Biotin is plain Vitamin B7. Biotinoyl tripeptide-1 is biotin attached to a small peptide chain — the peptide portion is the active part for hair growth, and it has stronger research support than biotin alone.

What grows lashes better than biotin?
Peptides (especially multi-peptide complexes), growth factors like EGF, and PDRN all have stronger peer-reviewed evidence for lash and hair growth than biotin. Prostaglandin analogs (like the active in Latisse) work fastest but carry side effect risks.