If you started a GLP-1 medication and, somewhere around month three, the shower drain went from "normal" to alarming — please read this carefully.

I am Dr. Sarah Williams. I am an OB-GYN, not a dermatologist. The reason that distinction matters — and the reason I am publishing this on the open internet rather than only telling my patients in my office — is that women on GLP-1 medications are getting bad advice about their hair, and they are paying for it both in dollars and in follicles they may not get back.

Most of you reading this have already been to your dermatologist or your primary care physician. Most of you have been told it is "telogen effluvium." Most of you have been told to "wait it out." Many of you have been handed a bottle of biotin, sold a $79 hair vitamin, or pointed at a $200 shampoo. And most of you, six to nine months later, are still shedding.

You have not failed. The advice was wrong. And the reason it was wrong has nothing to do with your hair.

It has to do with your gut.

Why an OB-GYN is the one writing this letter

I have been in practice for over six years at Williams Women's Health Group. The bulk of my patients are women navigating PCOS, perimenopause, fertility — and increasingly over the past three years, the side effects of GLP-1 medications.

By the time a woman describes the shedding to me, she has usually already been to a dermatologist. Often two of them. She has spent four to nine months trying to fix it with biotin, with hair vitamins, with shampoo, with prayer. She has stopped washing her hair with her fingertips because she does not want to see how much comes off.

I see this side effect earlier than dermatology does, because my patients on GLP-1 medications come through my door for the medication's other effects — fertility windows, hormone shifts, the way appetite suppression interacts with the cycle. Hair comes up in passing, during an annual exam. By then they have been shedding for months.

What I have learned, sitting across from those women week after week, is that the standard model of post-shock hair shedding does not describe what is happening to women on GLP-1. The standard treatment cannot, mechanically, work.

Let me show you why.

The mechanism, in plain language

GLP-1 medications work by suppressing appetite. That is the entire intended mechanism. You eat less. You lose weight. The medication is doing what it was prescribed to do.

But when appetite drops, two things happen at the same time — and one of them, almost no one is talking about.

First, protein intake drops. Hair is almost entirely keratin, which is protein. When the body is short on protein, it triages. Organs and skin get protected first. Hair is on the "non-essential" list. Shedding follows. This part, dermatology does understand.

Second — and this is the part nobody is treating — the bacteria living in your large intestine begin to starve.

The bacteria in your gut are not optional. They are the apparatus by which your body absorbs nutrients from food. They feed on dietary fiber. When you eat less, you take in less fiber. When you take in less fiber, the bacteria that need it shrink in number — measurably, within weeks.

Studies of patients three to six months into GLP-1 therapy show microbiomes that look meaningfully different from baseline. Specific strains drop. Diversity drops. The capacity of the gut to extract nutrients from food drops with them.

And here is what almost no one explains to women starting a GLP-1: the bacteria that are starving are the same bacteria your body uses to absorb biotin, iron, zinc, B-vitamins, and the protein your hair follicles need.

That is the analogy I use in my office, several times a week. It is not metaphorical. It is what is mechanically happening inside your body.

And the implication is clear. You cannot fix your hair until you fix the absorption pathway first. Whatever vitamin you put into a body whose gut bacteria are depleted is a vitamin that does not reach where it is supposed to go.

Why biotin specifically can't reach your follicles

A note on biotin, which is the most common thing women on GLP-1 are handed.

Biotin is absorbed in the small intestine and, importantly, the large intestine — by the same bacteria we just talked about. When those bacteria are depleted, biotin passes through largely unused.

What it does do, in many women, is contribute to cystic jawline acne. This is the side effect my patients tell me about most often after a few months of high-dose biotin. They came for hair. They ended up with acne. The hair did not improve.

If you have noticed jawline breakouts since you started a hair vitamin: that is your body telling you the dose is too high to be useful, and the absorption window is too closed for it to reach your hair anyway.

"Wait it out" is the most expensive mistake

I want to be specific here. Most of you have been given this advice by someone you trust. You need to understand why it does not apply to you.

Telogen effluvium can resolve on its own. That is the textbook. The trigger goes away, the follicles cycle back, the hair regrows.

On a GLP-1, the trigger does not go away. It continues for as long as you are on the medication. Your gut bacteria stay depleted. Your absorption stays broken. Your follicles stay starved. Shedding does not stop on its own — because the cause is still active.

And every month that passes during active shedding, more follicles enter a deeper dormancy. The window in which they wake back up easily begins to close.

I am going to be more direct than I usually am, because the cost of "waiting" is higher than what most women are told. For Black women, particularly, the cost compounds. The Black Women's Health Study has documented an elevated genetic risk for central centrifugal cicatricial alopecia — CCCA — in which prolonged dormancy can transition into permanent follicle scarring. Once scarring happens, no supplement, no medication, no shampoo brings the follicle back.

The average time from first symptom to CCCA diagnosis in Black women is over five years. You do not have five years. You have a window. Inside the window, this is reversible.

The protocol I now recommend in my practice

The protocol is short. It is not a five-step morning routine. It is one decision, made early.

You give your gut bacteria back what they have been deprived of, and you reseed the strains that have collapsed. That is the entire mechanism.

In practical terms, what works:

• Two prebiotic fibers, at clinically relevant doses

  Xylooligosaccharides (XOS) at 800 mg per day, and resistant dextrin at 500 mg per day. These are food for the bacteria you still have. They restore microbial absorption capacity in low-fiber diets.

• Four probiotic strains, reseeded daily

  Lactobacillus acidophilus, L. rhamnosus, L. reuteri, and L. fermentum — totaling 10 billion CFU per day. These are the strains most commonly depleted in low-intake patients. You replace what GLP-1 has thinned out.

• No biotin

  I cannot say this strongly enough. Adding biotin to a GLP-1 patient is paying twice for absorption that is not happening — once in dollars, once in jawline acne.

• A 60- to 90-day window of consistent dosing

  Microbiomes do not rebuild in two weeks. Two months is the floor. Three months is more reliable. If you abandon the protocol at week four because you do not see a difference yet, you have not been given enough time for the mechanism to work.

If you do this, in my experience and in the experience of the colleagues I trade notes with, the shedding noticeably reduces inside the first six weeks. Visible regrowth at the part and hairline begins around month three to four.

The formula I recommend — and the disclosure I owe you

About a year into recommending this protocol on paper to my patients, I was approached by the team at Herflow about formulating a single supplement that delivered the prebiotic-and-probiotic loadout I had been writing down on prescription pads. I went into that conversation skeptical. I came out of it convinced.

They were already producing a formula that matched, almost ingredient-for-ingredient, the protocol I had been building from clinical literature. The two prebiotic fibers at the right doses. The four probiotic strains at 10 billion CFU. Two capsules per day. No biotin. No "horse pill" sizing.

I asked them to put my name on it. I am paid a small consulting fee for that. You should know that. It is the disclosure I owe you, and the reason I am being explicit about it here is that I would rather you trust the rest of what I am saying because I have been honest about this part.

What also matters: a 90-day money-back guarantee in which you may use the entire bottle and still receive a full refund — including shipping — by emailing the company. No bottle return required. No phone calls. No retention scripts. One-click cancel on the subscription. These are not common in this category. They are part of why I felt comfortable putting my name on it.

See the formula I recommend 90-day money-back guarantee · 2 capsules a day · no biotin

Where you are in the recovery window

The reason timing matters this much is that follicle dormancy is not a single state. It is a slow gradient toward permanence. Every month inside the window, more of the gradient is recoverable. Every month past the window, less of it is.

Month 3 to 4 of your medication. Act now. The cost of acting is small. The cost of waiting another nine months is, in some cases, follicles you do not get back.

Month 6 to 9. Still well inside the window. Most patients in this range see their first regrowth by month four to five of consistent protocol.

Past month twelve. This works. It is harder. Start anyway. The follicles that have not yet scarred can still wake up. The ones that have, will not.

A note on what this letter is, and isn't

This is education. It is not medical advice for your specific case. I have not examined you. I do not know your labs.

Before you change anything, talk to your prescribing physician. Get your iron, ferritin, and thyroid checked if you have not already. Do not stop your GLP-1. It is the medication you need. The hair side effect is solvable without abandoning what the medication has done for the rest of your health.

If you do not have access to a clinician who is taking you seriously about this, the Herflow team has a customer support line that can answer questions about the formula. They are not allowed to give medical advice. But they can answer the structural questions about the protocol that I would answer if you were sitting in my office.

Questions I get most often

These are the questions women send my office before deciding whether this protocol fits them. I am answering them the way I would in person.

I have alopecia. Will this help me?

It depends on the type. "Alopecia" is a category, not a diagnosis. The protocol I am writing about addresses the gut-absorption mechanism that drives shedding on GLP-1 medications and other low-intake states. If your shedding came on after starting a GLP-1, after major dietary changes, or after a period of caloric restriction, it is exactly what was designed for that.

If you have been diagnosed with alopecia areata (autoimmune patchy loss), scarring alopecia / CCCA, or androgenetic alopecia (DHT-driven thinning), those have different root mechanisms and need different protocols. This is not a treatment for those conditions. Your dermatologist is the right point of contact.

That said, if you have an alopecia diagnosis and you are also on a GLP-1, the GLP-1 portion of your shedding may be on top of your underlying condition. Restoring absorption may stabilize that layer while your dermatologist works on the rest.

Is it safe to take long-term, and can I take it while still on my GLP-1?

Yes to both. The active ingredients are food-derived prebiotic fibers and well-studied probiotic strains used in clinical research at the same daily doses. There is no clinical reason to limit duration.

You should stay on your GLP-1. The protocol was designed to be taken alongside the medication — it addresses the absorption side, not the medication itself. Most of my patients use it through the recovery window — three to nine months — and then either continue at maintenance or discontinue. Always check with your prescribing physician if you have a specific health condition or are taking other medications.

One last thing

Your hair is not vanity. I am an OB-GYN. I see women every day for whom their hair is the way they recognize themselves in the mirror. It is the way their daughter and their granddaughter recognize them. It is — for women in our community in particular — a part of identity that no one else gets to define the importance of.

You did not start a GLP-1 to lose your hair. You started it for your blood sugar, your weight, your mobility, your fertility, your mental-health bandwidth — for the version of yourself you wanted to keep being.

You can have both. The medication that is helping your body, and the support your body needs to keep growing the hair that has always been yours.

The version of yourself who looks in the mirror in nine months is not deciding today between "this works" and "this doesn't." She is deciding between "I started" and "I waited." That is the only decision in front of you.

Don't wait this out. There is a window. We are still inside it. Go.

See the formula 90-day money-back guarantee