Growing new lashes and keeping the ones you have are two different goals.
🩺 Written by K.Y.J.A.M. Ho, MD PhD, medical specialist · reviewed by C. Pleiter, medical specialist · updated 23 August 2026 · sources & method
Lashes are hair, and hair grows on a cycle you can support but not force. Genuine lengthening comes from one class of prescription ingredient, prostaglandin analogues. Everything else, nutrition, gentle habits and good removal, mostly protects the lashes you have so fewer break and fall early. Extensions can look dramatic and can also thin your natural lashes if done badly.
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Strong Prescription prostaglandin serums genuinely lengthen lashes Moderate Iron and protein status support hair growth Emerging Biotin helps only in genuine deficiency
Two very different wishes get bundled into wanting better lashes: growing more and longer lashes, and holding on to the ones you already have. They are not the same thing, and most of what is sold as lash boosting is really about the second. That is worth knowing, because for most people the problem is not that lashes stop growing but that they keep breaking and falling out early.
Lashes are hair, and like all hair they grow on a cycle, a growing phase, then rest, then shedding. That cycle is short for lashes, which is why they never grow as long as the hair on your head, and it is why you cannot simply force them to grow faster by wanting it. What you can do is give the follicle good conditions and stop damaging the lashes you have.
The damage is usually mechanical and avoidable. Harsh eye-makeup removers, sleeping in mascara, over-enthusiastic use of a lash curler, and heavy or poorly applied extensions all pull lashes out or snap them at the root. Extensions in particular can look wonderful and, if they are too long or too heavy for your own lash, slowly thin what is underneath. Being gentler often does more than any tube of serum.
There is one thing that genuinely grows lashes, and it is a medicine, not a cosmetic. A prescription ingredient originally developed for glaucoma lengthens, thickens and darkens lashes, with real trial evidence behind it. It also has side effects around the eye, which is exactly why it is prescription-only and a decision for a doctor, not a beauty counter.
Nutrition sits underneath all of this. Low iron stores and crash dieting are linked to hair shedding, and lashes are hair, so if you are losing them suddenly it is worth looking at your general health rather than buying a stronger serum. Biotin, the supplement most associated with hair and nails, only helps if you are actually deficient, which is uncommon. The science below sets out what the studies actually show.
Serums and extensions work on the lash, but a strong lash starts with iron, protein and general health. If you want help getting that base right, the DrHealthy program looks at the whole picture with you. See how the program works.
Prostaglandin analogues genuinely lengthen lashes. The one ingredient with strong evidence for growing lashes is bimatoprost, a prostaglandin analogue. In the pivotal randomized, double-masked, vehicle-controlled trial that led to its approval, bimatoprost 0.03% significantly increased eyelash length, fullness and darkness compared with vehicle (Smith et al., 2012). A longer randomized trial confirmed that responder rates far exceeded vehicle and were maintained over twelve months, and importantly that the effect regresses after the product is stopped (Glaser et al., 2015). This is a medication with a real biological effect, not a cosmetic conditioner.
It has genuine ocular side effects. A pooled safety analysis of six randomized trials found the most common adverse events were conjunctival hyperaemia and eyelid pigmentation, with iris pigmentation rare (Wirta et al., 2015). These are the reasons the ingredient is prescription-only and belongs in the hands of a doctor who can weigh them for the individual, particularly anyone with pre-existing eye conditions.
Lashes follow a short hair-growth cycle. Eyelashes are terminal hairs with their own follicles that cycle through growth, regression and rest, but with a much shorter cycle and shorter shafts than scalp hair (Thibaut et al., 2010; Paus et al., 2016). This biology is why lashes have a natural maximum length and why patience, not force, is what supports them; you are working with a cycle, not overriding it.
Nutrition supports the lashes you have. Hair follicles depend on adequate iron and protein. Low serum ferritin, a marker of iron stores, is associated with hair loss in women (Kantor et al., 2003), and iron deficiency is a recognised, treatable contributor to hair shedding (Trost et al., 2006). Because lashes are hair, sudden or severe lash loss can be a sign of the same underlying issues and is a reason to see a doctor rather than escalate cosmetics.
Biotin is oversold. Reviews of biotin for hair and nails find that the cases of benefit essentially all involve an underlying deficiency or specific pathology, with insufficient evidence to support supplementation in people who are not deficient (Patel et al., 2017). For most people it is an expensive placebo.
Extensions carry real risks. Eyelash extensions and their adhesives have been documented to cause keratoconjunctivitis, allergic and contact reactions and ocular-surface damage (Amano et al., 2012), and the traction of heavy extensions can damage the natural lash over time. Done well and conservatively they are fine; done aggressively they can cost you the lashes they were meant to enhance.
Finding the cause before the fix. The practical order is to work out whether you have a growth problem or a breakage problem, and whether your general health is supporting hair at all, before spending on serums or extensions. Thyroid disease and iron deficiency both show up in hair.
What this does and does not promise. Nothing here is a guaranteed result, and prescription lash treatments and any medical cause of lash loss are handled by a doctor. This is educational information about how lashes work and what the evidence supports.
Putting this into practice. Most of the win is being gentler with the lashes you have. Remove eye make-up softly rather than rubbing, never sleep in mascara, go easy with the curler, and choose lighter, well-applied extensions if you use them at all. Support the follicle from the inside with enough protein, and if you shed suddenly, have your iron (ferritin) and thyroid checked by a doctor rather than reaching for a stronger serum. If you want genuine lengthening, that is a prescription prostaglandin serum and a conversation with a doctor because of the eye-related side effects. Skip the biotin unless you are actually deficient.
Treatment and foundation together. Lash products act on the follicle you have, but a follicle short of iron or protein, or under metabolic stress, is a weaker starting point. Addressing the foundation supports hair generally, lashes included, and sudden loss is a signal to have iron and thyroid checked by a doctor rather than to escalate cosmetics.
This is general medical information, not a diagnosis or a treatment. For advice about your own situation, and before changing anything about your medication, always talk to your own doctor.
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