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Oral Minoxidil for Hair Loss: Your FAQs Answered.

Oral Minoxidil for hair loss: your FAQs answered.



Minoxidil is a widely used and effective hair loss treatment. Typically applied to the scalp as a foam or liquid, some patients find it difficult to use in this form or can be bothered by side effects such as brittle, matted hair texture and scalp irritation.


Less well known but now growing in reputation is low-dose oral minoxidil for the treatment of pattern hair loss in men and women. In this article, we will answer some of the most frequently asked questions about oral minoxidil such as:


  • The history of minoxidil
  • How does minoxidil work?
  • How does minoxidil cause hair regrowth?
  • Why use oral minoxidil instead of topical?
  • What do clinical studies of oral minoxidil show?
  • What is the optimal dose of oral minoxidil?
  • Will it cause shedding like topical minoxidil?
  • How often should I take oral minoxidil?
  • How quickly will I see regrowth with oral minoxidil?
  • What happens if I stop taking oral minoxidil?
  • Who shouldn’t use oral minoxidil?
  • Can I take oral minoxidil with other hair loss treatments such as finasteride?
  • What are the side effects of oral minoxidil?


The history of minoxidil.

As a drug, Minoxidil has an interesting back story. Though it was initially developed as a treatment for ulcers, researchers noted that it powerfully dilated blood vessels and it was repurposed as a treatment for high blood pressure. In a further twist, a 1972 study on patients with high blood pressure observed hypertrichosis (unexpected hair growth) in over half of the patients. After a protracted legal battle between Upjohn, the original developers and Dr Guinter Kahn who had first reported hair growth on patients using minoxidil, the drug was patented to treat male pattern alopecia in 1986.


Eventually, in 1988, the FDA approved Rogaine for male pattern baldness and in 1991 for female androgenetic alopecia, though many doctors had been using it off-label throughout the 1980s, as its effects were so dramatic.


How does minoxidil work?

Because minoxidil is a vasodilator, it widens blood vessels. This very property which led to lower blood pressure also increases blood flow into the scalp. It is this mechanism which is thought to contribute to increased hair growth by flooding the scalp with oxygen and nutrients.


To work, minoxidil needs to be transformed into an active form, called minoxidil sulfate, which is responsible for most of the positive effects of hair growth. This step of bioactivation requires the presence of an enzyme called sulfotransferase, found in hair follicles. We all have different levels of sulfotransferase in the scalp which means that topical minoxidil doesn’t always work in the same way for everyone. Other drugs such as aspirin can inhibit sulfotransferase and stop minoxidil from working effectively.


How does minoxidil cause hair regrowth?

Minoxidil works by speeding up the telogen phase (also known as the resting phase of hair growth). Minoxidil pushes dormant hair follicles to prematurely enter the anagen or growth phase. This increased growth phase can lead to increased hair length as well as follicle diameter. However, a shortened resting phase can also lead to shedding which is known as telogen effluvium. (See our question on shedding below).


Why use oral minoxidil instead of topical?

There are several reasons why topical minoxidil may not be for everyone. Though topical minoxidil is generally safe and well tolerated, skin irritation is a relatively common side effect. Non-medical ingredients such as alcohol and propylene glycol in some topical preparations can lead to dandruff and contact dermatitis. Thankfully, oral minoxidil is thought to be safe even if you have had a skin reaction to topical minoxidil.


Some people do not respond to topical minoxidil because of a lack of the sulfotransferase enzyme in the scalp. However, when taken orally, drugs pass through the liver in a process called first-pass metabolism. In this case, sulfotransferases in the liver convert minoxidil to its active form.


What do clinical studies of oral minoxidil show?

Several studies have examined the effectiveness and safety of oral minoxidil with positive results.


One review of 17 studies, covering over 600 patients found that oral minoxidil was a safe and effective alternative for male and female patients who have not seen results with topical preparations. Though the main studied condition was pattern hair loss, the review also found that oral minoxidil could be effective and safe in other conditions such as chronic telogen effluvium, traction alopecia, loose anagen syndrome, alopecia areata, monilethrix, chemotherapy-induced hair loss and scarring alopecia.


Another recent study compared oral minoxidil (1mg) against topical minoxidil (5%) in female patients aged 18-65 with pattern hair loss. In this study, low-dose oral minoxidil was found to have a comparable effect to the topical solution, with a better shedding profile and a trend towards greater improvement in hair density.


What is the optimal dose of oral minoxidil?

As with any medicine, it is ideal to take the lowest dose possible whilst still achieving a treatment effect. The doses required for effective hair growth are much lower than those used for blood pressure control, which is typically between 10-40mg/day.


For female patients, the ideal dose is between 0.25-1.25mg per day. The largest study reviewing effective doses for the treatment of androgenetic alopecia found that the optimal dose of oral minoxidil in female patients is 1mg/day.


In male patients, lower doses are less effective, however, can be a good starting point to balance side effects with hair regrowth. Studies examining the optimal dosing for androgenetic alopecia in male patients found that doses between 2.5mg and 5mg are the most effective.


How often should I take oral minoxidil?

To treat pattern hair loss or balding, oral minoxidil can be taken once or twice daily. However, because oral minoxidil isn’t yet FDA-approved, no studies on the optimal dosing schedule have been performed. If you miss a dose of oral minoxidil, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.


Will oral minoxidil cause shedding as topical formulations do?

As with topical preparations, oral minoxidil is associated with a period of increased hair shedding that can last 3-6 weeks. This is because of the shortening of the telogen resting phase of the follicle. This causes the shedding of the existing hair as new hair in the growth phase comes through. Though alarming, this period of shedding is temporary, and it is important to be aware of this possible side effect to avoid premature discontinuation of treatment. Eventually, as the growth phase of the follicle is lengthened, an increase in hair length and follicle diameter can be noted. Generally speaking, higher doses of minoxidil are associated with a greater degree of shedding.



How quickly will I see regrowth with oral minoxidil?

It can take up to 4 months after starting topical minoxidil to notice any improvement in the coverage and/or thickness of your hair. However, some people can see an improvement in as little as 8 weeks.


This is because it takes time for your hair to convert from the resting phase to the growth phase of the cycle.


After 4 months, if you’re still noticing hair loss, this may not be down to ongoing shedding but possibly because minoxidil isn’t the right drug for your hair regrowth journey. 



What happens if I stop taking oral minoxidil? Will my hair fall out?

Minoxidil needs to be administered indefinitely to maintain existing hair follicles and sustain any new hair regrowth.


The effects of Minoxidil are only active if the drug is taken continuously. If the medication is discontinued, the effects are removed. Therefore, minoxidil should be considered a long-term therapy.



Who shouldn’t use oral minoxidil?

  • Cardiac patients: If you have a heart condition such as arrhythmia, or angina, had a recent heart attack or stroke or have any disorder related to your blood vessels, minoxidil could exacerbate these conditions.


  • Phaeochromocytoma: Patients with this rare type of endocrine tumor should not take minoxidil as it can cause the tumor to become more active


  • Kidney disease – as minoxidil is normally eliminated from the body via the kidneys, patients with kidney failure or chronic kidney disease should not take minoxidil as they can experience a dangerous build-up of the medication and increased side effects.


  • Patients prone to low blood pressure



Can I take oral minoxidil with other hair loss treatments such as finasteride?

Oral minoxidil is a relatively new addition to the hair loss armamentarium and as a result, there are no studies examining its use in combination with other medicines. However, according to Wilma Bergfeld, MD, a dermatologist from the renowned Cleveland Clinic, oral minoxidil is an inexpensive, safe and efficacious treatment for hair loss alone or in combination with other topical agents


What are the side effects of oral minoxidil?

Side effects of oral minoxidil are generally mild. In more serious cases, the dilation of blood vessels can lead to swelling of the face and extremities, rapid heartbeat/palpitations, or light-headedness. If you experience any of these symptoms on minoxidil, it’s best to withdraw the medication and seek advice from your healthcare provider.


If you drink alcohol or caffeine, stopping these can reduce the symptoms of low blood pressure and palpitations.


Rarely, minoxidil may cause hypertrichosis, with unwanted hair growth in areas away from the scalp such as the cheeks. Although it is exceedingly rare and reversible by discontinuation of the drug. Other less common adverse effects include postural hypotension/dizziness, lower limb swelling, mild blood pressure changes, and ECG changes. No severe adverse cardiopulmonary events have been noted.



Oral minoxidil can be strongly considered a safe and effective alternative for patients with pattern hair loss as well as other conditions causing hair loss. It has an acceptable safety profile and clinical studies have demonstrated that it is comparable to topical minoxidil. Because of easy dosing and bioactivation in the liver, low-dose oral minoxidil could show superior hair regrowth results for patients who have struggled with topical preparations.

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