Prostaglandin D2: Miracle Hair Loss Discovery… Or Just Another Sign Of Inflammation?

Read time: 10 minutes

Prostaglandin D2 Hits Headlines As A Baldness Breakthrough

In 2012, the dermatology departments of University of Pennsylvania and Johns Hopkins University generated a lot of buzz around a potential “miracle cure” for baldness.

The big discovery? A relationship between prostaglandin D2 (a fatty acid derivative) and male pattern baldness.

The researchers demonstrated, for the first time in humans, that a lipid derivative called prostaglandin D2 was elevated in balding areas – but not in hair-bearing areas – of men with hair loss. More importantly, they also discovered that prostaglandin D2 inhibits hair lengthening. The more prostaglandin D2 present, the shorter a hair grows.

The team suggested that by maybe inhibiting prostaglandin D2 in the scalp, hair loss might be stopped. And that got a lot of hair loss sufferers (and pharmaceutical companies) excited.

Prostaglandin-D2 inhibitors were already in trials as a treatment for asthma. It wouldn’t be hard to develop a topical for men’s scalp using the same technology.

The media went wild, claiming the “cure” for baldness was just around the corner. These researchers began talks with pharmaceutical companies to begin human trials. One article claimed the “cure” for baldness might reach shelves in 2 years. Then came another scientific overview, and even more excitement around the possibility that by inhibiting prostaglandin D2, we might grow back our hair.

Years Later… Is Prostaglandin D2 Still A Hair Loss Miracle?

Today, the buzz around prostaglandin D2 has faded. We haven’t heard much from the human prostaglandin D2 trials. And some of prostaglandin D2’s original hair loss research pioneers have even shifted focus.

So what happened? Does prostaglandin D2 really hold the cure for baldness?

Maybe… Maybe not.

This article uncovers what prostaglandins are, why scientists thought prostaglandin D2 held so much promise for hair recovery, and why prostaglandin D2 might not be the miracle hair loss cure after all.

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Important Note: this article was last updated in 2017. Since then, new research has come out clarifying (and contradicting) the role of prostaglandins in androgenic alopecia. As such, this article no longer reflects my exact viewpoints on the subject. We recently published a manuscript about inflammation, prostaglandins and fibrosis – you can read that here.

What Are Prostaglandins?

Prostaglandins are a group of lipids that our bodies generate at sites of injury, like damaged or infected tissues. They are a part of the body’s inflammatory response – meaning that prostaglandins over-express at sites of inflammation.

Prostaglandins have a variety of roles in the “promotion and resolution of inflammation” – like blood flow regulation, blood clot formation, cytokine expression, and even hormone regulation. Their presence changes the way that cells behave – sort of similar to a hormone.

The Bad News About Prostaglandins

In normal amounts, prostaglandins are fine (and even essential). But chronically elevated prostaglandin levels are a bad thing. Prolonged prostaglandin over-expression is associated with more allergies, autoimmune disease, arteriosclerosis, and now even hair loss.

There are many prostaglandin groups – all labeled by their molecular form – but the one that made hair loss headlines was prostaglandin D2 (PGD2).

What Is Prostaglandin D2?

PGD2 is a type of prostaglandin made in our central nervous system and in our skin tissue. On top of hair loss, PGD2 is also the same prostaglandin implicated in asthma. So if you’re also suffering from asthma, you might find the following information relevant.

How Do Our Bodies Make Prostaglandin D2?

Prostaglandin D2 is actually made from another prostaglandin called prostaglandin H2 (I know, the names aren’t that original).

When prostaglandin H2 (PGH2) comes into contact with an enzyme called prostaglandin D2 synthase, it gets converted into prostaglandin D2 (PGD2).

Not All Prostaglandin D2 Hurts Our Hair… Only The Kind That Binds To GPR44

In order for PGD2 to influence cell behavior, it has to bind to a cell’s receptor. There are a few different receptors to which PGD2 can bind, but the PGD2 receptor that’s implicated in hair loss is called GPR44.

When PGD2 binds to the receptor GPR44, hair loss soon follows. This is the one-two combination that hair loss sufferers (and preventers) want to avoid.

Summary So Far: How Prostaglandin D2 Triggers Hair Loss

Prostaglandin D2 is elevated in the bald areas of men with androgenic alopecia. This discovery reinforces previous research showing that in mice, PGD2 increases just before the regression phase of the hair cycle (in other words, prostaglandin D2 increases before hair loss occurs).

Interestingly, researchers also showed that by increasing PGD2 in mice, they can induce hair follicle miniaturization, sebaceous gland hyperplasia, and eventually alopecia. They can use PGD2 to “turn on” pattern hair loss.

So to summarize the the prostaglandin D2-hair loss connection:

  1. PGH2 gets converted into PGD2 by the enzyme prostaglandin D2 synthase
  2. Then that PGD2 binds to the receptor GPR44
  3. For unknown reasons, this triggers hair loss (or more specifically, hair length shortening).

Prostaglandin D2 Hair Loss Flow Chart

So how can we go about inhibiting PGD2 to protect us against pattern hair loss?

How To Decrease PGD2 (With Drugs)

Two Ways To Stop PGD2: Enzyme Inhibitors & Receptor Antagonists

In order to stop PGD2 from influencing a cell’s function, we need to either…

  1. stop PGD2 from ever forming, or…
  2. stop PGD2 from binding to a cell

Scientists are developing drugs to do this by…

  1. blocking the enzyme that converts PGH2 into PGD2 – prostaglandin D2 synthase. Or…
  2. blocking PGD2’s “anti-hair” receptor – GPR44.

Wait… Blocking Enzymes And Receptors Sounds Kind Of Similar To Other Hair Loss Drugs

And it should!

Blocking a substance’s enzyme and receptor is also how hair loss scientists approached reducing another hair loss “culprit”… DHT.

Before PGD2 came along, dihydrotestosterone (DHT) was considered the “cause” of hair loss. The argument was as follows:

In our scalps, testosterone gets converted into DHT by the enzyme 5-alpha reductase. DHT then binds to a cell’s androgen receptor, and for unknown reasons, the hair becomes sensitive to DHT and the follicles eventually shrink, leading to hair loss.

The solution for DHT? Block the 5-alpha reductase enzyme or the androgen receptor to decrease the amount of DHT in our scalps and maybe regrow some hair.

So came the creation of Propecia – a 5-alpha reductase enzyme inhibitor – and Spironolactone – an androgen receptor antagonist (blocker).

Here’s a side-by-side of how PGD2 and DHT form.

Prostaglandin D2 DHT Hair Loss Similar

Back To PGD2: The Good News For Pharmaceutical Companies

Like DHT inhibitors, a few known prostaglandin D2 inhibitors already exist. Here are a few:

  • Setipiprant (a GPR44 receptor antagonist)
  • Ramatroban (a GPR44 receptor antagonist)
  • Ricinoleic Acid (a prostaglandin D2 synthase enzyme inhibitor). The name sounds scary, but it’s actually just a fatty acid found in castor oil.

So are these PGD2 inhibitors helping us regrow any hair?

Are Prostaglandin D2 (PGD2) Inhibitors Regrowing Any Hair?

PGD2 Clinical Trials… No News Yet

Unfortunately, we haven’t heard word about clinical trial results, nor about the original PGD2 trials from a few years back. This makes me assume that the trials aren’t producing significant signs of hair regrowth.

But there are also non-trial participants – hair loss researchers and forum members who compounded their own PGD2 inhibitors. These experimenters have already begun testing PGD2-inhibiting substances and logging their progress on private hair loss forums. The most common PGD2 inhibitor of choice: Setipripant.

So what are their results?

PGD2 Hair Loss Forum Testers… Not Much (If Any) Regrowth

Some testers are reporting an arrest in hair loss. But unfortunately, none are showing significant signs of regrowth… even after a full year of testing.

But it’s not all bad news.

The Silver Lining: PGD2 Inhibitors + PGE2 Promoters Might Regrow Hair

Some researchers have combined PGD2 receptor blockers with PGE2 promoting substances, and with much better success.

Just check out the regrowth results from Swiss Temples. His “prostaglandin protocol” seems like a bit over-the-top – especially with the safety concerns of some of the substances. But it’s reaping results.

These anecdotes suggest that a PGD2 inhibitor + PGE2 promoter is probably better for hair regrowth, especially versus a PGD2 blocker alone. But based on radio silence from the PGD2 trials and the lacking results from others’ anecdotes – it seems like a PGD2 blocker alone isn’t going to regrow much hair.

Why Aren’t PGD2 Inhibitors Regrowing Much Hair?

While research is still ongoing, it might have to do with that question researchers never answered…

How exactly does prostaglandin D2 cause hair loss?

Maybe the answer is that prostaglandin D2 induces something else… calcification.

Prostaglandin D2 Doesn’t Just Trigger Hair Loss… It Also Triggers Calcification

Calcification is the build-up of calcium deposits in tissues where it doesn’t belong (for example, our soft tissues or our arteries). And studies show that PGD2 is a calcification inducer – meaning that PGD2 triggers calcification.

The bottom line: wherever PGD2 over-expresses, calcification may soon follow.

Calcification Is A Chronic Progressive Condition

The causes of calcification are complex, multifaceted, and not fully understood. But the important takeaway is this:

Calcification is chronic and progressive. If you take away whatever triggers calcification (for example, PGD2), you might stop more calcification from accumulating, but you likely won’t remove the calcification already present.

Scalp Calcification Precedes Hair Loss

The connection between calcification and hair loss was made over 70 years ago when researchers observed in those who were bald, the blood vessels supporting those dormant follicles had become completely calcified.

In fact, calcification precedes hair loss. Calcium buildup in our blood vessels restrict blood flow to our hair follicles, which reduces oxygen and nutrient flow to the follicles. This causes the hair to slowly shrink, until it disappears entirely.
Prostaglandin D2 Calcification Hair Loss

Due To Calcification, PGD2 Inhibitors May Only Stop Hair Loss, But Not Regrow Much Hair

Remember: researchers haven’t yet uncovered exactly how PGD2 causes hair loss. Based on the evidence, my guess is this:

PGD2 induces calcification. That calcification then restricts blood flow to our follicles, until the follicle shrinks and the hair disappears.

If this is true, then it makes perfect sense why a PGD2 inhibitor may only stop future hair loss. If we block PGD2, we prevent future calcification… But we never get rid of the calcification that’s already there.

Why We Should Still Try To Reduce PGD2

It’s still in our best interest to decrease PGD2 expression. Doing so may protect us from hair loss and reduce the symptoms of allergies (and even asthma).

So, is there any way we can go about doing this naturally? Without drugs that haven’t completed the rigor of human trials?


How To Reduce PGD2 (Naturally)

Change Your Diet

PGD2 is derived from arachidonic acid, which is an omega 6 fatty acid.

Omega 6 fatty acids are found predominantly in cooking oils (think: canola, olive, safflower, sunflower, and corn), but are also prevalent in many processed foods. They’re considered to activate many pro-inflammatory pathways in the human body.

Going Back To Asthma: Linking Together PGD2, Arachidonic Acid, and Diet

As you ingest higher levels of arachidonic acid, you might also increase the expression of pro-inflammatory messengers in the body – like PGD2. This can lead to a variety of chronic ailments, one of which is asthma.

Conversely, omega 3 fatty acids seem to bolster an anti-inflammatory effect. These fatty acids are found in quality seafood – like wild salmon, scallops, and oysters.

A balance of omega 6 and omega 3 fatty acids help to optimize proper inflammatory responses. Unfortunately, in the case of most first-world diets, people over-consume omega 6 fatty acids and under-consume omega 3 fatty acids.

This was recently evidenced in a large-scale study on children’s diets from 2010. Researchers found that children who ate 3+ burgers a week were at a higher risk for asthma, whereas children who ate more fish and fruits were at a much lower risk.

What’s important to note isn’t that these children were eating burgers… It’s that these children were eating a higher ratio of omega 6 to omega 3 fatty acids (~15:1), and thereby more likely to over-express PGD2 and other inflammatory biomarkers (the indicator being their asthma symptoms). The end-result of prolonged PGD2 expression: breathing problems. The children eating a more balanced ratio omega 6:3 ratio (~4:1) likely expressed less PGD2, and were thereby protected from asthma.

Eat Less Omega 6, Eat More Omega 3

So, if you’re worried you might be over-expressing PGD2, you may want to consume more polyunsaturated omega 3 fatty acids, and consume fewer polyunsaturated omega 6 fatty acids. Doing so might benefit other inflammatory conditions in your body, and even your hair health.

And if you wanted to take this a step further, you can even make efforts increase PGE2.

The One-Two Punch: Decrease PGD2, Increase PGE2 – All Naturally

Remember that the best prostaglandin-related regrowth results so far have been achieved by decreasing PGD2 and increasing PGE2.

We already know that a diet that restricts omega 6 fatty acids may decrease PGD2 expression. But did you also know we can increase PGE2 expression naturally too?

Here to increase PGE2 expression:

Get into the sun as often as possible.

UVB radiation has been shown to upregulate PGE2 expression. All you need to do is start getting into the sun during peak hours of UVB exposure. In doing so, you’ll increase vitamin D and PGE2 expression – which may help tremendously in preventing hair loss (and even regrowing some hair).

Summary Of The Prostaglandin D2-Hair Loss Connection

In 2012, researchers discovered that increases prostaglandin D2 (PGD2) expression reduces hair lengthening. The researchers hypothesized that a PGD2 inhibitor might halt hair loss and even regrow hair.

Unfortunately, we haven’t heard much from the PGD2-inhibitor human trials. On top of that, hair loss forum trials with PGD2 blockers did little more than halt hair loss.

However, some hair loss experimenters are documenting regrowth by both blocking PGD2 and increasing PGE2 expression. The net – if we’re going to try a prostaglandin protocol and we want to maximize our chances for hair regrowth, we need to both decrease PGD2 and increase PGE2.

Fortunately, we can decrease PGD2 and increase PGE2 naturally. Restricting omega 6 fatty acid consumption may decrease PGD2 expression throughout our bodies, and getting UVB radiation (from the sun) can increase PGE2.

And there you have it. I’ll update this article as more news comes out. In the meantime, drop a question in the comments section!

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    49 thoughts on “Prostaglandin D2: Miracle Hair Loss Discovery… Or Just Another Sign Of Inflammation?”

    1. Is there any connection between 5AR and PGD2 ? (though PUFAs are anti-metabolic and anti-thyroid while DHT and 5AR steroids are pro-metabolic and pro-thyroid , it’s tough to see a positive correlation between both of them and yet both increase to cause hair loss) I have read some anecdotal reports here and there where some bodybuilders get hair loss from T derived steroids but they cease while taking them with Vit K/D and mag.

    2. Hi Rob!
      If calcification causes hair loss, what’s the correlation between calcification and the always feared DHT? Does one cause the other?

      • Hey Jolly – expect an article on this soon! The short: there’s definitely a correlation between DHT and calcification, but it’s a bit convoluted. DHT alone might be protective against calcification. However, DHT in the presence of increased androgen receptors + an imbalance of calcification regulators appears to trigger calcification. If true, this explains the DHT paradox (why increased DHT grows body hair but decreases scalp hair) and a host of other paradoxes in MPB. I’ll have the article up before the end of the year! (It’s also a chapter from the new book).

    3. Hi, Rob.
      the article seems to give very important insight regarding how diet affects PGD2 levels in scalp with high Omega6-3 ratio.
      Regarding PGE2 expression & general increase in Vitamin D levels its necessary to maximise our sunlight exposure.I read that its best to get maximum close to full body exposure in sun but has been confused weather our scalps should be covered or not. Please advice regarding this.

      • Hey Ankur,

        It’s tough to say with certainty. When it comes to increasing vitamin D levels (and testosterone), full body exposure is monumentally better than just exposing your arms and face. But as for PGE2 – the answer is a little less clear. PGE2 increases in tissues exposed to UVB radiation, so the more surface area exposed, the more PGE2 expressed. But the science on PGE2 and hair regrowth is still under evaluation, and it might just be that we only need PGE2 to increase in scalp tissues (and not necessarily everywhere else) for a pro-hair effect to occur.

        I wouldn’t worry about covering your scalp while out in the sun. And when it comes to general health, consistent full-body sun exposure is one of the best things you can do. But as far as full body UVB exposure increasing PGE2 expression and thereby benefiting our hair MORE than just UVB exposure to our scalps alone – that we don’t yet know.

    4. Hi Rob.

      Question regarding the massage.

      JD moyer recently answered a comment on his blog from a reader who talked about feeling and hearing clicking, crunch, noises when doing the massage.

      I have also noticed this. As I can hear clicking and crunching when doing some of the techniques. Espeically in areas where scalp was hardest.

      JD and the reader stated that this could be the breakdown of calcification ?

      Did you ever experience this ?


      • It’s a great question, and yes – I did experience it (especially in the first few months). I liken the crunching/clicking to two things:

        1) Swollen tissue. This is often the case when someone massages for too long, too hard, and too often. Usually these symptoms subside after a few days of lighter / no massaging.

        2) The breakdown of calcification / fibrosis / fascia.

        It’s tough to tell which case anyone falls into, but it’s commonly reported and I don’t think it’s that problematic (in fact, many people who report these sensations also report regrowth in later months). With that said, not everyone who reports regrowth experiences this cracking and popping. If it’s bothering you, or if you’re shedding more in addition to the popping, I’d ease off for a few days and see if you fall into category #1.

    5. Rob thanks for your answer.

      I felt this feeling in fact when I first began the massages, especially on the vertex where funny enough I felt more thin skin(tight).

      It doesn’t hurt at all, which makes me think that this may not be #1 category.

      This appears more now where my temples are. And guess what, this is where I’ve had recession.

      And I don’t get this clicking really on my sides , which are pilable.


    6. Hey Rob, I’m a 39 African American male, I have one issue and this is as redundant as it can but hell what’s our solution or treatment??? I’m balding/thinking in the Apex area, your research articles have opened my eyes to all these different drugs but I’m very anxious

      • Hey James – thanks for reaching out. I found success reversing hair loss with the diet, lifestyle, and mechanical stimulation exercises highlighted in the book. For a lucky few, reversing hair loss is as simple as correcting a nutrient deficiency. For the overwhelming majority (like myself), it takes complete overhauls in diet, plenty of sleep/sun, and the right mechanical stimulation to reverse any accumulated calcification / fibrotic tissue in order to allow for the hair to begin to regrow.

    7. Hi Rob, this maybe irrelevant but on a slightly different tack, could there be a link to people I know that have particularly strong hair growth and the medication I believe they must all be taking for Diabetes?

      • Hi Mikey,
        Sorry for hijacking the question like this lol but which diabetic medication are you talking about ( I doubt it’s metformin)

      • Hey Mikey – I apologize in my delay getting back to you. I’m curious about this too… I’ve never heard of this connection and was wondering if you could elaborate in regards to the medications and hair growth you’ve observed in these medicated diabetics (is it regrowth on the scalp, increased body hair, good hair maintenance, etc.)? Thanks for commenting.

        • Hi, I am unsure of the medication that all these male friends and acquaintances were taking, they were all type 2 diabetics with an age range of 60 to 75 year, all with noticeably full heads of greyish hair…..regards Mikey

      • Hey Lisa – the evidence suggests that increased PGD2 may be a consequence of increased androgens. So as long as the hair loss is female pattern hair loss (the typical diffuse thinning we see in women – usually closely linked to PCOS or menopause), then yes – the PGD2 and PGE2 relationships should hold true.

    8. I rececenty have vp shunt insertion, noticed a faster baldness happening! Could it be because i dont have uv exposure for the last 3 months, i am mostly indoor under rehab facility. I have been taking seizure medications (depakote 500mg 2X/ day) for the past 8 years. Now I’m taking fish oil, D3 & multivimin supplements too.

      • Hey Erik,

        Interesting… It’s certainly possible that the shunt surgery and your increased rate of hair thinning are connected. Anecdotally – I’ve had two friends who’ve had the surgery, and ironically, each has incredibly thick hair and no recession (even years later). From my understanding, the surgery is life-saving, so it beats keeping your hair by a landslide.

        Another possibility: the increased hair thinning could be connected to the stress of surgery. Many people report hair loss post-surgery – especially surgeries performed on the neck and head. In a lot of cases, the hair loss subsides (and the hair may even grow back) many months after surgery.

    9. I’m a 56 year old female and started losing my hair AT THE ROOTS last year. I went to several doctors, had loads of blood tests done, it showed my Vit D was low in the normal range, as was my iron (low in normal range) and I had antibodies in my thyroid, although my levels were OK. I’ve heard of Hashimoto’s but the endocrinologists I went to said I don’t have it and dismissed my concerns (or didn’t have an answer!) I am SO FRUSTRATED! I have lost 2/3 of my hair volume and each strand is getting thinner!

      I don’t know what to do!

      A dermatologist put me on Spironolactone but said it could take up to 6 months to see any results.

      I’ve heard of the 4 items to add to your diet: Aloe Vera Juice (how much??), Flaxseeds (3 TB/day), biotin (I take in huge doses) and Fish Oil (I already take).

      • Hey Barb – I’m sorry to hear about your experience. With both low-normal iron and vitamin D, I wouldn’t rule out hashimotos just yet. Other ways you can check your thyroid function is by measuring metabolism via resting pulse rate and oral body temperature. If your resting pulse is consistently lower than 60 beats per minute, or your body temperature is consistently lower than 98 degrees Fahrenheit, those signs all point to some form of hypothyroidism.

        Spironolactone takes at least six months for results to show – and the only impressive results I’ve seen from that drug in men took over six years to manifest. Overall, I think spironolactone resolves the symptoms – not the causes – of hair loss. As a result, it’s only mildly effective.

        Adding certain things to your diet might be helpful, but unfortunately, diet is more or less limited to slowing or stopping hair loss and not necessarily reversing it.

        I wrote another article about the causes of hair loss which you can read here:


        It might help you determine your personal causes of hair loss, and how to go about finding an effective treatment.


    10. I am a 73 y.o.woman, going on 43….am told by everyone I look 20 years younger..no one believes me when I tell them my age….good genes….in good health…recently lost 34 lbs, working on 20 more…I am an RN….my only med. prob.is hypothyroid, which I know can cause hair loss and of course post menapausal…I was hypertensive for 20 years and on Beta Blocker…but with the weight loss, my B/P has normalized and am off the BB….have been slowly losing hair on top of my head, but now losing all over…Panic. I have always had a monstrous head of hair…now very fine, limp, thin…I take 2,000 IU D3, 2,000 mcg B12(methylcobalamine) sublingual, Multivitamin/whole food combo…112mcg Synthroid, (TSH, T4 Normal)…and stopped taking FishOil
      And started taking Krill Oil, 500 mg/day….heard it was BETTER than Fish Oil and contained supplemental help for eye health….am I beating a dead horse….??? Is there something else I can do to regain my healthy mane???…Is Krill Oil okay as a substitute for Fish Oil…??? I am really a vain person…inherited…lol..any suggestions??

      • Hey Shirley,

        The causes of hair loss vary for each individual, and there’s certainly more you can try. Have you tested for Small Intestinal Bacterial Overgrowth (SIBO), iron overload / deficiency, or PCOS? For women, those are great places to start. New research is showing month-by-month that these conditions might be behind the etiology of female pattern hair loss.

        With more information, you can begin treating the underlying causes and keep moving from there. It’s a process of trial and error, but for many people, it’s worth the health (and hair) discoveries.


    11. That’s why Indians in Brazil are never bald
      they eat Acai the only food with 1:1 Omega 6 and 3
      plus Flaxseed which is rich in omega 3
      They called in Semente de Linhaca
      So Acai cures baldness blocking PGD2

    12. I’ve just listened to a video by someone called DAVID MCKENNA who claims he has found the secret to regrowing hair – he has a spice & herb formula which he claims reduces PGD2. The web address of his video is – [link redacted]

      Have you heard of him? He sounds very convincing.

      • Hey Bruce,

        I ended up redacting the link to David McKenna’s website because it was an affiliate link for his product. It’s possible this was an accident, and the person who linked you to his material was the one who sent you the affiliate link. But I don’t allow affiliate links in the comments sections of my site, and I wanted to be transparent about why I redacted that portion of your comment.

        The reality is that David McKenna is not a hair loss researcher — he is a marketer. For evidence: in the before-after photos he presents of his readers, the speed at which the hair was “regrown” outpaces the actual speed that hair can regrow. Some of his highlighted case studies — particularly the women — show near-complete hair recoveries in mere weeks, when in reality, a healthy person with zero hair loss would need 6+ months to reach the same hair length.

        Moreover, David McKenna’s claims do not stand up to scientific scrutiny. PGD2 might be implicated in the balding process, but elevated PGD2 is more likely a symptom of inflammation rather than the underlying cause of hair loss. That’s why I wrote this article — to highlight the misconceptions that PGD2 is a hair loss miracle discovery, when in reality, evidence suggests this couldn’t be further from the truth.


    13. Could there be any link in hair loss between the PGD2 and Absolute Eosinophils. I am a 69 female who worked hard in this last year to lose 40 pounds, and now my once very thick hair is very, very thin, dull, lifeless. I can shake my head and shed like a dog. My protein levels where a below normal range. I have RA levels above normal range, and an auto immune/Morphea (which seems to be in remission). But last blood work showed my eosinophils WAY elevated. I do not have asthma, nor allergic reactions, and doctors just drop the conversation there. I have had an acute case of tendonitis in both hands from using weights that were to heavy for me. That seemed to cause a huge inflammation response, which is about when my hair starting falling out; 3-4 months ago.

      • Hey Donna,

        Interestingly, there is a connection between PGD2 receptors and eosinophil trafficking, at least in certain tissues:



        Is your hair loss more autoimmune in nature, or has it been diagnosed as telogen effluvium, classical female pattern hair loss, or both? The reason I ask is because this would implicate different pathologies in its onset.

        If autoimmune, it’s likely more closely related to your morphea / other outstanding health issues. If the latter, it’s more likely a consequence of post-menopausal hormonal shifts (that may exacerbate pre-existing subclinical conditions like hypothyroidism) and/or stress-related, likely the result of a prolonged calorie deficit (as evidenced from your recent weight loss).

        Have things gotten better since you last reached out?


    14. Hi Rob,

      I was on corticosteroid inhalers for several years (20+) and noticed some hair loss as I got older but not significant. Over the past 2 years I weaned myself off of them just because I didn’t want to continue putting these into my lungs/body. I manage well without them but definitely had better control of my asthma when I was taking daily. I have however noticed an big increase in hair loss & recession over this time. From what I understand steroids should increase hair loss but I have recently discovered the PGD2/asthma connection and wondering if my inhaler use had a possible byproduct of reducing PGD2. Could it be possible?

      • Hey Jeff,

        Asthmatics tend to over-express PGD2 in their lung tissues, and as a result, some asthma treatment drugs have been in clinical trials to determine if PGD2-reducing drugs help improve outcomes for asthma sufferers. But I’m not sure any of these drugs have made their way to the public. It’s likely your inhaler worked through a different mechanism of action, and it’s likely that its effects on PGD2 have either yet to be measured, or are negligible. I used to have asthma and used an inhaler for years.

        Which inhaler brand did you use? I can look it up and get more information.


        • Hey Jeff,

          Thanks. It looks like it’s a synthetic corticosteroid which is meant to be anti-inflammatory. That means that PGD2 reduction may be a symptom of its effects, but that it’s likely not the drug’s main mechanism of action.

          My guess is any benefits you saw to your hair was the result of fluticasone’s anti-inflammatory properties, and less so its effects on PGD2.


    15. hi,
      if the root cause of hair loss is calcification . then vitamin k might help since its said to lower calcification. i tink you should take quite large doses. ray peat thinks its one of the main deficiencies in humans (like vitamin d) …im definetly gonna try this out !

      • Hey Moritz — calcification is certainly implicated in AGA, but what makes this more complicated is that there are a variety of different ways a tissue can become calcified. Much of this starts inflammation, but the pathology of that inflammation matters.

        For instance, inflammation induced via diet is one way for calcification to begin. Another way: injury. Another way: chronic tension. So treating the calcification with vitamin K2 may help prevent or stave off its progression. However, unless we go back one step further, we might only be putting that process in a “holding” pattern.


    16. Hi Rob,
      I am balding and i have allergic asthma due to allergies (every time the season changes i have some period of asthma)
      I eat almost everything but the things i eat in very big quantities are milk, sweet biscuits, bread, drinks (like sprite) 🙂
      I changed my lifestyle one month ago into:
      vegetables and fruits, less milk, less bread, less drinks, less sugar
      nofap for blockin DHT
      massage with oil in the scalp
      and today i found out your article about PGD2 so i will include omega3 foods
      Do you think i have hope to regrow hair and cure my asthma?
      Is my path correct?
      Thank you very much for your article

      • Hey Nick,

        Thanks for reaching out.

        Firstly, there’s always hope! We’ve seen impressive hair recoveries even for people in advanced stages of hair loss. But as far as setting individual expectations, there’s too much variance to give you a definitive answer here.

        I think you’re taking the right steps (at least from a health perspective) in modifying your diet/lifestyle to potentially reduce prostaglandin D2 activity. Scalp massages also help a lot of people. Whether or not this is enough, you should know in 8-12 months. If not, you can always begin to add in additional treatments / interventions – more powerful DHT reducers, etc. – until you find a regimen that works for you.


    17. Hi Rob,

      I know many on the Ray Peat forum talk about aspirin being a good inhibitor of the negative prostaglandin, have you read much into the use of aspirin for this?


      • Hey Matt,

        Aspirin inhibits the enzyme cyclooxygenase, which is used to make a variety of prostaglandins. The challenge is that some prostaglandins seem to positively regulate the hair cycle, while others seem to negatively affect hair lengthening and maybe even accelerate hair thinning. So, I’m not sure that widespread prostaglandin inhibition is the best answer. And I’d also be concerned about regular aspirin use in relation to the subsequent potential for long-term toxicity.


    18. Is there a link between Niacin intake and PGD2, and thus hair loss? I am starting to take Niacin daily (500mg orally), but am concerned that it will accelerate hair loss, via its increase in PGD2.

    19. I’m female and have been trying to get to the bottom of my FPHL. It started in 2019. Got itchy around my hairline and then hairline started to thin. Diagnosed by two dermatologists as FPHL with no family history whatsoever. Only thing was that I was using female testosterone cream and not using HRT. Doctors said probably not the cause but who knows. Just recently went through two months of diffuse shedding. Thyroid tested and normal. Around the time of the hair loss, I started to get very itchy skin (especially facial), persistent cough and asthma. Knowing that PGD2 can be linked to asthma and allergies it’s got me thinking. My PGD2 has never been tested. Do you think it’s worthwhile?


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