Minoxidil Shedding – What to Expect & When it Stops

Article Summary

Starting minoxidil and seeing more hair fall out? You’re not alone. This article breaks down the phenomenon known as the “dread shed”—a temporary spike in hair loss that can happen when beginning treatment. We explore why this shedding occurs, what it means for your hair cycle, and whether it’s actually a sign that minoxidil is working. We also look at recent research to tell us how long shedding typically lasts and why it may predict better results in the long run. If you’re panicking at the first signs of hair fall, this piece is for you.

Full Article

Minoxidil is a medication that began as a treatment for hypertension (high blood pressure). However, after observing excess hair growth during the testing stages of the drug, minoxidil was repurposed as a treatment for hair loss. Topical minoxidil soon received FDA approval for the treatment of both male and female pattern hair loss, while oral minoxidil is also used as an off-label treatment for hair loss.^[1]Suchonwanit, P., Thammarucha, S., & Leerunyakul, K. (2019). Minoxidil and its use in hair disorders: a review. Drug design, development and therapy. 2777-2786. Available at: … Continue reading

So, if minoxidil is a treatment for hair loss, why does it cause an increase in hair loss when you start using it? Yes, you did read that right – minoxidil can actually cause an increase in hair loss as part of what is often called the ‘dread shed.’ This phenomenon was demonstrated in a retrospective study of 435 patients with androgenic alopecia (AGA) who were prescribed low-dose oral minoxidil [≤5 mg per day] by the same clinic. Self-reported adverse events were recorded for each of the users and, of the 435 patients, 32% experienced increased hair shedding.^[2]Sanabria, B., de Nardo Vanzela, T., Miot, H. A., & Ramos, P. M. (2021). Adverse effects of low-dose oral minoxidil for androgenetic alopecia in 435 patients. Journal of the American Academy of … Continue reading

This is evidently cause for concern – if you have just started minoxidil treatment to prevent hair loss, a sudden increase in hair loss is possibly the last thing you would hope and expect to experience. So what is it about minoxidil that causes this to happen, how long does it usually last, and is it actually a good thing? In this article, we will explore the hair cycle and minoxidil in detail to provide answers to each of these questions.

The Hair Cycle

To understand why minoxidil can increase hair shedding, let’s first take a refresher on the hair cycle. Our hair is constantly going through a cycle of growing (anagen), regression and transition (catagen), resting (telogen), and shedding (exogen), which it repeats continuously. 

Healthy hairs grow for anywhere between 2 and 8 years, and there is a correlation between the length and strength of a hair and the time spent in anagen. Catagen is the transition from anagen to telogen, a period of approximately 2 weeks during which the follicle regresses from the hair shaft and disconnects it from the blood supply, preventing any further growth. Telogen follows and lasts for 2-3 months, with a new hair shaft beginning to develop at the base of the follicle underneath the now resting hair shaft. Exogen then represents the transition from telogen to anagen, with the growing hair shaft pushing out the old hair shaft.^[3]Natarelli, N., Gahoonia, N., & Sivamani, R. K. (2023). Integrative and mechanistic approach to the hair growth cycle and hair loss. Journal of clinical medicine. 12(3). 893. Available at: … Continue reading 

In the healthy scalp, the percentage of hairs in each of the hair cycle stages is thought to remain fairly consistent. At any one time, evidence suggests that approximately 9% of the hairs on a healthy scalp are in the telogen phase (although there are some suggestions that this figure may actually be too high).^[4]Natarelli, N., Gahoonia, N., & Sivamani, R. K. (2023). Integrative and mechanistic approach to the hair growth cycle and hair loss. Journal of clinical medicine. 12(3). 893. Available at: … Continue reading These hairs exist in a largely asynchronous fashion, with hair follicles progressing through the hair cycle according to their own unique pattern. Hair follicles undergo between 10 and 30 full cycles, and it is normal for up to 150 hairs to fall out per day without there being an underlying hair loss problem, as the hairs are constantly being replaced.^[5]Bergfeld, W. (2009). Diffuse hair loss: its triggers and management. Cleve Clin J Med. 76(6). 361-370. Available at: https://doi.org/10.3949/ccjm.76a.08080 This keeps hair fall relatively consistent, preventing periods of significant hair shedding.

What Happens to the Hair Cycle during AGA?

AGA, the hair loss condition for which topical minoxidil is an approved treatment, is caused by damage to the hair follicle that contributes to its miniaturization. This is when individual strands of hair become smaller and smaller over time, eventually becoming vellus hairs that are shorter, thinner, and more white, which makes them difficult to see. We have a previous article that explores AGA-induced hair loss in great detail, but let’s summarize the key characteristics below:

• Perifollicular fibrosis – collagen deposition in the spaces around the hair follicles restricts the room within which hair shafts are able to grow, acting as a physical barrier to hair growth.
• Increased telogen:anagen ratio – healthy scalps typically have 1 telogen hair for every 12 anagen hairs (1:12 telogen:anagen), but people with AGA may exhibit ratios that are as high as 1:4 or even 2:5. The telogen phase also lengthens, with hairs spending longer in a state of non-growth.
• Shortened anagen phase – as previously mentioned, the length of an anagen phase directly corresponds to the length of the eventual hair shaft, and people with AGA typically exhibit anagen phases that become shorter with every hair cycle.

Although the exact mechanisms underlying AGA are yet to be fully understood, it is evident that AGA is a progressive and cumulative process that occurs due to harmful factors damaging the hair follicle and shortening the anagen phase.

How Minoxidil Works

Minoxidil is also yet to be fully understood, but several mechanisms have been suggested that could explain how it reduces hair loss:

• Vasodilation – Minoxidil started out as a treatment for hypertension, so its function as a vasodilator is well documented. Studies have shown that minoxidil increases blood flow by opening potassium channels, reducing high blood pressure. However, an unintended benefit of this function is increased blood flow to the hair follicles, providing them with nutrients and oxygen that help to prolong the anagen phase.^[7]Messenger, A. G., & Rundegren, J. (2004). Minoxidil: mechanisms of action on hair growth. British journal of dermatology. 150(2). 186-194. Available at: … Continue reading
• Prostaglandin mediation – Minoxidil has been shown to increase the production of prostaglandin E2 (PGE2) in cultured human dermal papilla fibroblasts, the specialized cells that sit at the base of the hair follicle. It is thought that PGE2 may protect hair follicles from damage.^[8]Michelet, J. F., Commo, S., Billoni, N., Mahé, Y. F., & Bernard, B. A. (1997). Activation of cytoprotective prostaglandin synthase-1 by minoxidil as a possible explanation for its hair … Continue reading
• Growth factor mediation – Studies have shown that minoxidil has the potential to upregulate the expression of several growth factors that support hair growth, including vascular endothelial growth factor in human dermal papilla cells.^[9]Lachgar, Charveron, Gall, & Bonafe. (1998). Minoxidil upregulates the expression of vascular endothelial growth factor in human hair dermal papilla cells. British Journal of Dermatology. 138(3). … Continue reading

It is likely that minoxidil reduces hair loss through a combination of several mechanisms, including those noted above and perhaps others that are yet to be discovered.

How Might Minoxidil Cause the Dread Shed?

So, we know the basics of the hair cycle, some of the mechanisms that contribute to pattern hair loss, and some of the mechanisms by which minoxidil may reduce hair loss. But what does all this have to do with the ‘dread shed ’? Fortunately, observing the effects of minoxidil is more straightforward than trying to understand how it works, and there is one key effect which is believed to contribute to the increase in shedding: shortening of the telogen phase.

As we previously discussed, a key characteristic of AGA is lengthening of the telogen phase, which causes an abnormal amount of scalp hair to be in a state of arrested growth at the same time. It is widely believed that minoxidil directly addresses this issue by both shortening the telogen phase and accelerating the telogen to anagen transition. In one study,  application of topical minoxidil to rats caused a dramatic shortening of the telogen phase, falling from 20 days to just 1-2 days.^[10]Mori, O., & Uno, H. (1990). The effect of topical minoxidil on hair follicular cycles of rats. The Journal of dermatology. 17(5). 276-281. Available at: … Continue reading In a separate study that was also conducted in rats, topical minoxidil caused a significant switch from the telogen to anagen phase as quickly as 10 days after beginning treatment (Figure 2).^[11]Shatalebi, M. A., & Rafiei, Y. (2014). Preparation and evaluation of minoxidil foamable emu oil emulsion. Research in pharmaceutical sciences. 9(2). 123-133. Available at: … Continue reading

We could only find one clinical study that has investigated the telogen-anagen shift in humans at an early stage after beginning minoxidil use. They conducted a 24-week trial in which men with AGA either applied topical minoxidil [5%] or topical cetirizine for the first 16 weeks, then stopped use for 8 weeks. Although the results were not statistically significant, they showed that minoxidil caused an increase in the percentage of anagen hair and a decrease in the percentage of telogen hair, supporting the idea that minoxidil rapidly induces shortening of the telogen phase.^[13]Mostafa, D. H., Samadi, A., Niknam, S., Nasrollahi, S. A., Guishard, A., & Firooz, A. (2021). Efficacy of cetirizine 1% versus minoxidil 5% topical solution in the treatment of male alopecia: a … Continue reading

In accelerating the telogen to anagen transition, minoxidil also causes “hair follicle synchronization” or synchronization of the hair cycle. As we highlighted earlier, healthy scalps are somewhat ‘protected’ from significant hair shedding events due to the asynchronous nature of the hairs and their individual hair cycles. However, due to the increased density of telogen follicles in the AGA-affected scalp, minoxidil causes a greater-than-normal percentage of hairs to enter anagen at the same time. This syncing of the hair cycles then results in more hairs being pushed out at the same time.

So, to summarize the process that is believed to be the key factor behind the dread shed:

• In AGA, a greater number of hair follicles are in telogen
• Minoxidil treatment accelerates the transition of these hair follicles from telogen to anagen and causes many follicular units to become synchronized
• The transition leads to initiation of the shedding phase (exogen)
• Increased hair shedding occurs

Is The ‘Dread Shed’ Real?

Until very recently, evidence of minoxidil-induced hair shedding was either anecdotal or provided by studies of minoxidil in which increased hair shedding was noted as an adverse event. However, a newly published study sought to investigate the shedding phase in detail.

In this 2025 study, 49 patients with AGA used topical minoxidil [2% or 5%] for 24 weeks. Total hair shedding was quantified daily by the participants, who self-assessed their hair fall after combing, after washing, and on the pillow after sleeping. This was then averaged every 4 weeks and compared to the level of hair shedding prior to starting treatment. They found that the participants who used 5% minoxidil exhibited increased hair shedding (relative to pre-treatment) for 4-8 weeks, while the participants who used 2% minoxidil exhibited increased shedding for 8-12 weeks (Figure 2).^[14]Bi, L., Kan, H., Wang, J., Ding, Y., Huang, Y., Wang, C., Du, Y., Lu, C., Zhao, M., Sun, W. & Su, T. (2025). Whether the transient hair shedding phase exist after minoxidil treatment and does it … Continue reading 

This study provides definitive evidence that minoxidil does cause an initial shedding phase. However, importantly, hair shedding eventually fell below baseline levels in both groups, indicating that the initial shedding phase is temporary and that minoxidil did begin to reduce hair loss.

Is Initial Hair Loss Actually a Good Sign?

The same authors investigating the minoxidil shedding phase also sought to determine whether the amount of shedding had any association with treatment efficacy. They compared peak relative hair shedding (within the first 12 weeks) to changes in AGA severity using the Basic and Specific classification (BASP), which is a universal hair loss classification system that is used to assess the distribution and severity of hair loss in men and women of all races. They also compared peak relative hair shedding to several trichoscopy measurements, including hair density, hair diameter, and terminal hair proportion.^[16]Bi, L., Kan, H., Wang, J., Ding, Y., Huang, Y., Wang, C., Du, Y., Lu, C., Zhao, M., Sun, W. & Su, T. (2025). Whether the transient hair shedding phase exist after minoxidil treatment and does it … Continue reading

Interestingly, in the 5% minoxidil group, a significant association was found between the amount of initial hair shedding and hair density, hair diameter, and the proportion of terminal hairs. In other words, people who lost more hair in the ‘dread shed’ actually experienced greater outcomes from minoxidil treatment. Furthermore, participants who initially shed the most hair in both the 2% and 5% minoxidil groups demonstrated the greatest improvements in AGA severity by week 24.^[17]Bi, L., Kan, H., Wang, J., Ding, Y., Huang, Y., Wang, C., Du, Y., Lu, C., Zhao, M., Sun, W. & Su, T. (2025). Whether the transient hair shedding phase exist after minoxidil treatment and does it … Continue reading 

These results are very interesting – not only does the initial shedding phase indicate that the minoxidil is working, but more shedding may even predict better treatment outcomes! So, if you’ve just started treatment, don’t fear the shed!

Final Thoughts

Minoxidil is an FDA-approved treatment for AGA but, in some cases, it can cause increased hair shedding in the early stages of use. Known as the ‘dread shed,’ this phase is believed to be caused by minoxidil shortening the telogen phase of the hair cycle, causing old hairs to fall out. This shedding is even more pronounced due to the increased density of telogen hairs present in the scalps of people with AGA. However, this shedding is only temporary, typically lasting between 4 and 8 weeks. Moreover, people who experience more shedding in this initial phase may actually experience greater overall outcomes from their minoxidil treatment. So, if you have just started minoxidil and are noticing increased shedding, don’t panic – it is most likely a sign that the minoxidil is working.