Topical Latanoprost For Hair Loss: Results, Doses, & Side Effect Concerns

In this ultimate guide, we’ll explore the evidence on latanoprost, dive into the mechanisms and clinical data regarding hair growth, and identify who might be a good candidate for this experimental intervention. We’ll also specify which formulations, dilutions, and usage frequencies are reaping the best results in terms of both efficacy and safety.

Finally, we’ll uncover critical caveats with its use – including lesser-discussed (but significant) safety risks – and where to get latanoprost (should you choose to incorporate it into your regrowth regimen).

Latanoprost: Key Takeaways

• Drug. Latanoprost is a drug that changes the activity of substances called prostaglandins. It was originally used to treat glaucoma, but after patients began reporting thicker eyelash hairs following its use, it has since been repurposed as a topical and tested on hair loss sufferers.
• Clinical data. Two clinical studies testing topical latanoprost for androgenic alopecia suggest that 0.1 mL x 0.1% latanoprost and 1-2 mL x 0.005% latanoprost improve hair counts, with visual improvements occurring in 30-50% of people over 6-8 months. While both formulations equate to ~0.1 mg of latanoprost exposure daily, preliminary data suggest that lower concentrations (i.e., 0.005%) are much more tolerable for patients, at least in terms of scalp irritation. For alopecia areata of the eyelashes, 3 clinical studies suggest that 0.005% latanoprost has no effect. For alopecia areata of the scalp, one clinical study suggests that 0.005% latanoprost may improve hair growth in ~25% of patients, but that treatments such as 0.05% betamethasone diproprionate reap superior efficacy.
• Safety. Clinical data on topical latanoprost indicate a strong safety profile when used at 1-2 mL x 0.005% to 0.01% daily. At higher concentrations and lower volumes (i.e., 0.1 mL x 0.1% latanoprost), one study found that 50% of patients reported symptoms of scalp irritation – suggesting that these formulations may evoke skin sensitivities in a relatively large number of people. Finally, none of the clinical studies on topical latanoprost for hair growth ran longer than 6-8 month. This is a problem, because long-term safety data are not yet established despite well-defined long-term risks, like pigmentation changes to the skin, eyes, and hair. Long-term clinical studies on latanoprost for glaucoma show that up to 10% of patients experience a darkening of their irises, with the effect beginning after one year of treatment. For these reasons, we have significant reservations about the long-term viability of latanoprost when used on the scalp – particularly for people who have lighter colors of skin / hair and who would prefer to not experience any hypopigmentation.
• Best practices. While topical latanoprost is a popular treatment amongst dermatologists and certain online hair loss circles, we have significant reservations about its long-term viability – mainly because of the unknown risks (but high potential) for hypopigmentation in the skin, hair, and (perhaps) eyes – depending on systemic leakage. If you decide to try topical latanoprost, it seems to be most appropriate for those with androgenic alopecia, and at dilutions of 1-2 mL x 0.005% latanoprost daily.

What is latanoprost?

Latanoprost is a drug developed to treat disorders of the eye – specifically, glaucoma. Originally formulated for delivery as eye drops, some users began reporting the elongation and/or regrowth of eyelash hairs.^[1]https://jamanetwork.com/journals/jamaophthalmology/fullarticle/413134 Resultantly, researchers started investigating whether latanoprost – when formulated as a topical – might also enhance hair regrowth in other areas of the body, such as the scalp.

How does latanoprost work?

Latanoprost modulates levels of prostaglandin F2 – a substance our bodies produce that is derived from essential fatty acids (i.e., omega 6 fatty acids). More specifically, latanoprost stimulates the activity of the prostaglandin F2 alpha receptor. This allows for prostaglandin F2 levels to increase in cell sites, and when this occurs in eye tissues, it can reduce (or alleviate) ocular pressure and thereby improve cases of glaucoma.^[2]https://www.ncbi.nlm.nih.gov/books/NBK540978/

How might latanoprost regrow hair?

There’s evidence that the eyelash hair regrowth reported by many latanoprost users isn’t just happenstance. For instance, as prostaglandin F2 activity increases…

1. Microvascular networks tend to widen, thereby improving blood, oxygen, and nutrient transport to hair follicles affected by hair loss.
2. Mitosis (i.e., cellular division and proliferation) increases. When more hair follicle related cells divide, more cells can contribute to hair follicle growth overall. ^[3]https://pubmed.ncbi.nlm.nih.gov/15854125/
3. Prostaglandin D2 activity may simultaneously decrease – because precursor molecules for prostaglandins start shifting toward prostaglandin F2 alpha production and away from prostaglandin D2 production.^[4]https://www.frontiersin.org/articles/10.3389/fphys.2020.594313/full This is relevant because some evidence implicates prostaglandin D2 as a contributor to the balding process, so lowering its activity may help improve hair growth.^[5]https://pubmed.ncbi.nlm.nih.gov/33854354/

Interestingly, many of the above mechanisms (i.e., improved vasodilation and prostaglandin modification) overlap with the suspected mechanisms of the FDA-approved hair loss drug, topical minoxidil. As such, it’s no surprise that in a case series on 300+ patients using eye drops of latanoprost to treat glaucoma, 77% saw hypertrichosis (i.e., additional hair growth) in the areas surrounding the eyes. ^[6]https://www.jaad.org/article/S0190-9622(01)70206-X/fulltext

With all of these cases, it’s also not out-of-the-question that latanoprost might also help regrow some scalp hair if reformulated as a topical.

In fact, this was corroborated by a 2002 study on primates (i.e., stump-tailed macaques) who happen to be one of the only other species to also suffer from pattern hair loss, or androgenic alopecia. Over an 8-month study, monkeys receiving a topical application of 0.5 ml x 0.005% to 0.05% latanoprost daily showed improvements to hair loss and cosmetic degrees of hair regrowth.

The anecdotes on eyelash hair growth in glaucoma patients – and the preliminary evidence of hair regrowth on balding monkeys – certainly provides a strong enough signal to further investigate topical latanoprost as a hair loss treatment in humans.

So, over the last 20 years, what does the clinical evidence on latanoprost show?

Human evidence: topical latanoprost for the treatment of hair loss

While the data are limited (so far), clinical studies on latanoprost for hair loss have been conducted on both androgenic alopecia, telogen effluvium, and alopecia areata.

Clinical study on androgenic alopecia (2011)

In its first-ever randomized, double-blinded, placebo-controlled clinical trial, researchers tested topical latanoprost on 16 men with early-stage androgenic alopecia.

Each participant received two drops of 0.1% latanoprost daily – one drop per receding temple region – equating to 0.1 mL of solution applied daily. In other words, each man applied 0.1 mg of latanoprost per day.^[7]https://pubmed.ncbi.nlm.nih.gov/21875758/

2011 clinical results

Over the course of 24 weeks, daily application of 0.1 mg of latanoprost…

• Improved terminal hair counts and hair density versus placebo
• Improved the ratio of anagen:telogen hairs versus placebo (i.e., growing vs. shedding hairs)
• Did not cause any serious adverse events

The results were reflected statistically through phototrichogram data (i.e. the gold-standard for clinical research on hair loss disorders).

While the data seem encouraging, it’s important to point out three caveats. Across all latanoprost users:

1. 8 of 16 men did report skin irritation-like effects – such as dermatitis. So, the risk of mild side effects were relatively high (i.e., 50%).
2. 50% of men demonstrated what investigators called a “clinical improvement”. In other words, they saw improvements in at least two criteria points on the phototrichogram: increased hair density, increased hair counts, etc.
3. Of the remaining men, 44% demonstrated no response, and 6% demonstrated a “poor” response – meaning things got worse for them versus placebo.

In other words, latanoprost seemed to work well in half of participants, with the other half of participants showing hair loss stabilization or no response at all.

For what it’s worth, this is a common trait among hair loss drugs that target factors like histamine responses and/or prostaglandins – for instance, minoxidil and cetirizine. ^[9]https://perfecthairhealth.com/histamine-and-hair-loss-is-there-a-use-for-antihistamines/ For some, these drugs work wonders. For others, they see no effect. Why?

In our estimation, the dichotomies in responses are likely related to the following:

• The degree of inflammation in the scalp – as studies have shown inflamed scalps respond more poorly to topicals such as minoxidil^[10]https://pubmed.ncbi.nlm.nih.gov/8496421/
• The level of histamine activity surrounding hair follicles – as this problem may contribute to some cases of androgenic alopecia, but not all^[11]https://perfecthairhealth.com/histamine-and-hair-loss-is-there-a-use-for-antihistamines/
• The activation of these compounds – in the case of minoxidil, its sulfation (which can be improved with retinoic acid, microneedling, and/or switching to oral minoxidil)^[12]https://my.perfecthairhealth.com/courses/minoxidil/topical-minoxidil/

Therefore, this initial (albeit, small) clinical study on topical latanoprost suggests that it might have a place in treating some cases of hair loss, but not all.

Clinical study on androgenic alopecia and telogen effluvium (2018)

In 2018, another research group investigated the use of topical latanoprost by itself (and combined with topical minoxidil) in the treatment of men and women with androgenic alopecia or telogen effluvium.^[13]http://www.surgicalcosmetic.org.br/details/618/en-US/latanoprost-and-minoxidil–comparative-double-blind–placebo-controlled-study-for-the-treatment-of-hair-loss

First, the researchers split 123 participants into six groups, with each group testing one of the following:

• G1: Placebo (i.e., nothing)
• G2: 5% minoxidil
• G3: 5% minoxidil + 0.005% latanoprost
• G4: 0.005% latanoprost
• G5: 5% minoxidil + 0.01% latanoprost
• G6: 0.01% latanoprost

Unfortunately, the investigators didn’t specify how much solution each participant applied once daily. Based on the photos of participants featured inside their study, many participants had moderate levels of hair loss and beyond, which would likely require at least 1-2 mL of solution to cover all balding regions. So, we can only make rough estimations as to how much daily exposure of these drugs each participant received.

Note: the absence of daily drug exposure volume is just one of the many flaws in this study. We’ll uncover more issues soon.

2018 clinical results

Over the course of 180-240 days, 25 of the 123 people withdrew from the study for reasons that the investigators state were “not related to the research” – though they don’t specify what those reasons were. Withdrawal rates were mostly equivalent across all six groups, which leaves us with 98 people and 16-18 participants per group for statistical comparisons.

Among those who remained, here are the key findings:

• No side effects were reported, with no significant signs of dermatitis or scalp irritation for any participant across all treatment groups.
• These groups saw statistically significant hair count improvements versus placebo:
  • G2: 5% minoxidil
  • G3: 5% minoxidil + 0.005% latanoprost
  • G4: 0.005% latanoprost
  • G5: 5% minoxidil + 0.01% latanoprost
• These groups did not see hair count improvements versus placebo:
  • G6: 0.01% latanoprost
• The response rates (i.e., the percent of people seeing visually cosmetic regrowth) were:
  • G2: 5% minoxidil – 35%
  • G3: 5% minoxidil + 0.005% latanoprost – 36%
  • G4: 0.005% latanoprost – 19%
  • G5: 5% minoxidil + 0.01% latanoprost – 6%
  • G6: 0.01% latanoprost – 0%

Here are some photos the investigators featured of participants using 5% minoxidil and 0.005% latanoprost – albeit from an extension period that ran up to 240 days:

And here is data regarding anagen hair counts (i.e., the number of “growing” hairs) across all groups and time periods (day 2, day 92, and day 182):

What can we glean from this 2018 study?

First, let’s start off by interpreting a good signal from this study.

Topical formulations of latanoprost that are of higher volume and lower concentration might greatly minimize the risk of side effects.

If we recall from the 2011 study on topical latanoprost, two drops of 0.1% latanoprost totaling 0.1 mL of daily use led to skin irritation-related side effects in 50% of participants. But in this study on 0.005% to 0.01% latanoprost applied daily at 1-2 mL of volume, no adverse events were reported.

It might interest you to know that both of these studies likely exposed participants to the exact same total amount of latanoprost each day. It’s just that the 2011 study used a higher concentration (i.e., 0.1%) but with less volume of topical (i.e., 0.1 mL), whereas the 2018 study used a 10-20x lower concentration (i.e., 0.005% to 0.01%) but with 10-20x more volume (i.e., 1-2 mL).

Yet mathematically, both studies exposed their participants to ~0.1mg of latanoprost daily.

This is important, because it suggests that 0.1mg of latanoprost may become a lot more tolerable for hair loss patients when it is spread out over a larger area. So, if nothing else comes from this study, we’re at least encouraged by this signal.

So what else can we surmise?

1-2 mL daily of 0.005% latanoprost may improve hair counts for a portion of people with androgenic alopecia and/or telogen effluvium… particularly if combined with 5% minoxidil

According to the data presented by the research team, 0.005% latanoprost by itself was effective at improving hair parameters, as was 0.005% latanoprost + 5% minoxidil.

However, we need to keep in mind the response rates here: just 35% to 36% of participants in these groups saw visual regrowth. That’s not a lot, and it gives credence to the belief that while latanoprost might work for some people, it’s probably not appropriate for all hair loss sufferers.

What shouldn’t we glean from this 2018 study?

Looking at all of the data from this study can be confusing. After all, we have 6 different groups statistically measured across one another, with varying methodologies applied for some groups (like extension time periods for those using 0.005% latanoprost + 5% minoxidil), and with poor clarity in writing regarding both results and discussion organizations.

Nonetheless, we’ve read online about some people presuming that this study gives us enough insights to include the following. So, before adopting similar opinions, please read our counterarguments below:

Fallacy #1: this study suggests that 0.01% latanoprost might be less effective than 0.005% latanoprost

It’s not abnormal to make this assumption given the data presented. After all, the groups using 0.005% latanoprost saw a 35% and 36% response rate, whereas the groups using 0.01% latanoprost saw a 6% and 0% response rate.

Moreover, it’s not unusual to see dose-dependent effects in medicine – where some drugs have a strong therapeutic benefit at lower concentrations but can have opposing or toxic effects at higher concentrations. We discuss these relationships in our guide on flutamide.

Nonetheless, there are significant methodological flaws in this study that do not allow us to jump to this conclusion. Here are a few:

• Participant dropout rates were nearly 20%. This increases the likelihood of survivorship bias, whereby those who are left at the end of the study are only there because they actually are seeing an effect… while those who were seeing no benefit quit. This phenomenon artificially enhances “response rates”, and while it can be controlled for statistically using Bayesian modeling, the investigators did not do this.
• There was an unknown number of telogen effluvium participants. Telogen effluvium is a type of hair loss that differs from androgenic alopecia. It’s often caused by stress, micronutrient imbalances, and/or chronic conditions like hypothyroidism. It also self-resolves given enough time away from a stressor, or after the micronutrient imbalance or chronic condition is corrected. This study includes an unknown number of telogen effluvium patients, and no data on how many were in each group. With group sizes of just 16-18 people per treatment, keep in mind that all it would take would be 5-6 people “recovering” from telogen effluvium (which is likely not treatable through the mechanisms suspected from latanoprost) to hit a 35% “response rate”. That’s a huge problem… especially because the investigators don’t specify their method of randomization – which means there could be a disproportionate number of telogen effluvium sufferers in one of these groups – either artificially stuffing down or inflating their response rates.
• Participants were included if they had quit other hair loss treatments only 4+ weeks prior. Multiple studies definitively show that abruptly quitting hair loss topicals, such as minoxidil, results in a telogen effluvium-based shed that can take upwards of 6+ months from which to fully recover back to baseline. That’s the entire duration of this study. As such, any study that includes participants who just quit other treatments or topicals only 4+ weeks ago could be capturing a huge percentage of participants who happen to be entering into a telogen effluvium shed due to quitting those treatments… which would obfuscate any hair count results from introducing a new treatment during the same period.

As such, we need to be incredibly careful about drawing any efficacy or comparison conclusions from this study. It’s entirely possible that 0.005% and 0.01% latanoprost are equally effective… but that the groups receiving higher dilutions of latanoprost had poorer results because of participant sampling. Without better data, we just don’t know.

As an aside, when discussing this study across our own team, we were even apprehensive to mention the positive safety signal – as this 2018 study is so poorly designed that any conclusions whatsoever are potentially problematic and/or at-odds with the real-world experiences of latanoprost users.

Nonetheless, we have to work with the data currently available, and these two studies on topical latanoprost are all that we’ve got (so far) for androgenic alopecia.

So, what about other hair loss disorders, such as alopecia areata?

Clinical studies: topical latanoprost for the treatment of alopecia areata

To date, there have been five publications (to which we could find) assessing topical latanoprost for alopecia areata. Here are their quick summaries and results:

Alopecia areata of the eyelashes and eyebrows

A 2003 case report details the experience of an 11-year old female who experienced alopecia areata of the eyelashes after recovering from a viral illness. After multiple failed treatments, doctors eventually tested topical latanoprost – at an unknown dilution – which was applied daily for a period of six months. During that time, photographic assessments show a near full recovery of all lost eyelashes.^[14]https://pubmed.ncbi.nlm.nih.gov/12724722/

A 2009 clinical study tested 0.005% latanoprost – at an unknown volume – on a total of 26 men and women with alopecia areata of the eyebrows and eyelashes. Participants applied latanoprost to just one side of the face, with the other side acting as an intra-patient “control”. After four months, researchers saw partial hair recovery in just one patient, and concluded that topical latanoprost was no more effective than applying nothing at all. Aside from a transient headache fro one patient, no adverse events were reported.^[15]https://pubmed.ncbi.nlm.nih.gov/19620039/

Interestingly, these results were mirrored by prior clinical studies done on similar dilutions of topical latanoprost for eyelash-related alopecia areata from 2005 and 2008.^[16]https://pubmed.ncbi.nlm.nih.gov/16310083/^[17]http://www.iranjd.ir/article_98048_64fda5d6552e3e9d714cc2162d5686a4.pdf As such, it appears that the data (so far) suggest topical latanoprost does not improve this specific hair loss disorder for the overwhelming majority of people trying it.

Alopecia areata of the scalp

Finally, a 2021 randomized clinical study tested daily applications of 0.005% latanoprost versus 0.05% betamethasone diproprionate (an autoimmune-related medication) for the treatment of scalp-related alopecia areata in 50 patients.^[18]https://ijdvl.com/a-randomized-comparative-study-of-the-efficacy-of-topical-latanoprost-versus-topical-betamethasone-diproprionate-lotion-in-the-treatment-of-localized-alopecia-areata/

Unfortunately, the researchers did not specify the amount (in mL) of topical applied daily. As such, we cannot estimate daily exposure volumes.

Over a 16-week period, 24% of patients using 0.005% latanoprost saw improvements, whereas 56% of patients using 0.05% betamethasone diproprionate saw improvements. In fact, patients in the 0.05% betamethasone diproprionate group also tended to see a faster recovery and a more dramatic reduction of alopecia areata lesions.

Therefore, the researchers concluded that 0.05% betamethasone diproprionate was superior to 0.005% latanoprost in the treatment of scalp alopecia areata.

Topical latanoprost for hair loss: summaries of the clinical studies

From what we can glean across all clinical studies on topical latanoprost for hair loss:

• Androgenic alopecia / pattern hair loss: When applied daily at a total exposure volume of 0.1 mg, topical latanoprost seems to improve 30-50% of androgenic alopecia cases over a six-month period. Concentrations of 1-2 mL x 0.005% latanoprost are preferred, particularly when combined with 5% minoxidil. Moreover, 1-2 mL x 0.005%-0.01% latanoprost seems to be a safer formulation than 0.1 mL x 0.1% latanoprost – even though both formulations equate to a 0.1 mg daily exposure volume.
• Alopecia areata of the eyelashes: Currently, the totality of evidence suggests that 0.005% latanoprost at undisclosed daily usage volumes does not work, minus one or two case reports.
• Alopecia areata of the scalp: One clinical study shows that 0.005% latanoprost improves alopecia areata of the scalp in ~25% of participants, but that its response rate is just half that of 0.05% betamethasone diproprionate (another autoimmune treatment), and that patients using 0.05% betamethasone diproprionate respond more quickly versus 0.005% latanoprost.

What about safety?

It’s easy to look at these studies and note that dilutions of 1-2 mL daily of 0.005% to 0.01% were well-tolerated for nearly all participants, with only a handful of minor, transient adverse events reported across all patient cohorts testing this formulation. As such, it’s easy to presume that topical latanoprost must be safe.

We have significant reservations with that conclusion.

After all, these topical latanoprost studies for hair growth ran – at most – 8 months. While no serious adverse events were reported during these short timeframes, there is a well-known phenomenon that occurs from long-term latanoprost use, and one that does not typically show up until after one full year of treatment: pigment changes.

In glaucoma patients, pigment changes of the iris begin to occur after one year of daily latanoprost use, and they worsen over time – affecting up to 10% of glaucoma patients.^[19]https://www.ncbi.nlm.nih.gov/books/NBK540978/ Other studies suggest an incidence as high as 70%, depending on the eye color & duration of use.^[20]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1771317/

This is because regular latanoprost use increases melanin activity (i.e., the activity of cells that produce pigmentation in our skin, eyes, etc.). The effects, over time, can be quite dramatic. Just see the results from this patient, who was treated for glaucoma in their right eye with latanoprost (picture A) but not in their left eye (picture B). It’s as if we are looking at two different eyes. ^[21]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1771317/

As such, a critical question remains: does latanoprost applied topically produce the same effects in the skin, hair, and (potentially) through the eyes via systemic absorption?

Unfortunately, we have no way of knowing… because the clinical studies have not yet been conducted. Moreover, none of the studies on topical latanoprost for hair loss ran even remotely long enough to measure if this effect would also apply to the scalp.

In cases of treatments producing serious, cosmetically-unwanted adverse events – like a darkening of scalp skin – we tend to err on the side of caution and say that without more data, most people should be seriously cautious about long-term use of topical latanoprost. Perhaps better data will demonstrate this is not a concern, but until we have that data, we don’t feel comfortable recommending topical latanoprost as a guinea pig experiment to members here… even despite its popularity online as an adjuvant hair loss treatment.

For more contraindications and side effects from latanoprost, please visit this resource.^[22]https://www.ncbi.nlm.nih.gov/books/NBK540978/

Latanoprost: best and worst candidates

You are likely a candidate for latanoprost if:

• You have androgenic alopecia
• You are planning to use latanoprost alongside better-studied treatments (and not as a standalone treatment)
• You are not concerned about the unknown risks of pigmentation changes that tend to start presenting after 1+ years of latanoprost use

You are likely not a candidate for latanoprost if:

• You don’t have androgenic alopecia
• You are concerned about the unknown risks of pigmentation changes that tend to start presenting after 1+ years of latanoprost use

Summary

Latanoprost has some limited clinical data supporting its use for androgenic alopecia, but with response rates of 30-50%, it’s unlikely that this treatment is right for most hair loss sufferers. For these reasons, we recommend people use other prostaglandin analogues instead – such as minoxidil – and only resort to latanoprost if they’re using it as an add-on to their regimen and if they’re comfortable with the unknowns about its long-term safety profile.

For alopecia areata of the eyelashes, latanoprost is unlikely to help. For alopecia areata of the scalp, one small study found that topical latanoprost may help up to 25% of people. However, that same study also found that 0.05% betamethasone diproprionate was twice as effective at producing a response rate versus latanoprost, and that it also worked faster than latanoprost.