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Topical Minoxidil

Key Takeaways

Topical minoxidil is the FDA approved form for treating hair loss.

On average about 1.4% of the minoxidil solution is absorbed into the scalp.

Patients will have a varied response to topical minoxidil.

Minoxidil is shown to increase Vascular Endothelial Growth Factor (VEGF) expression by as much as six times in the hair follicle.

Minoxidil can not only help patients with AGA, but also Alopecia Areata, Traction Alopecia and other types of hair loss.

Topical minoxidil can also be used to increase density in eyebrow and facial hairs.

It’s most common side effect seems to be irritant contact dermatitis often caused by other ingredients in the solution.

Minoxidil is deathly toxic to cats and should be kept away from them.

Topical minoxidil used for treating hair loss patients with AGA Alopecia Areata, Traction Alopecia and etc.

What is Minoxidil

Minoxidil is a vasodilator drug developed during the 1970s as a treatment for hypertension. Much like finasteride, doctors noticed hair growth as a side effect of the oral minoxidil medication which lead to topical minoxidil solution (also known as Rogaine) being introduced as a hair loss treatment. It was first introduced as a 2% solution in 1986 and later in a more potent form, a 5% solution in 1993. While oral minoxidil is still available, topical minoxidil is the FDA approved form for treating hair loss which is the focus of this guide.   

Topical minoxidil used for treating hair loss patients with AGA Alopecia Areata, Traction Alopecia and etc.

Mode of Action

After a topical application of minoxidil, on average about 1.4% of the solution is absorbed into the scalp. A higher concentration solution or a higher application frequency will lead to a higher absorption rate. The systemically absorbed minoxidil does not cross the blood – brain barrier and has a half-life (time it takes for the body to excrete 50% of the absorbed dose) of around 3 hours. This leads to 95% of the systemically absorbed minoxidil and its metabolites being excreted via kidneys in about 4 days.

Once minoxidil reaches the hair follicle, it is transformed into minoxidil sulfate utilizing the enzyme sulfotransferase. This enzyme is important because patients whose scalp shows a higher expression of this enzyme tend to respond better to minoxidil. This explains the varied response to minoxidil seen in different patients where it tends to work well for some leading to significant hair growth while ineffective for others. This also explains the finding that serum or tissue concentration of minoxidil does not correlate with hair growth.

The exact mechanism in which minoxidil leads to hair growth is still unknown. That being said, there are several pathways where it helps the follicle regrowth. Minoxidil is shown to increase Vascular Endothelial Growth Factor (VEGF) expression by as much as six times in the hair follicle which leads to an increased blood flow to the follicle.

On the other hand, minoxidil is also known to stimulate prostaglandin E2 production leading to a prolonged anagen phase.

Treatment Protocol

Although topical minoxidil has been approved for the treatment of AGA, it has also been used for treating other hair loss types as well as regrowing eyebrow and facial hairs with some success. The 5% minoxidil solution is prescribed for male pattern hair loss while the 2% solution is often recommended for female hair loss. The solution is applied twice daily on the affected region at a dose of 1mL per session. The downside of minoxidil is that it should be applied for life in order to maintain the results. Discontinuation of minoxidil will lead to a considerable shed within 3 – 4 months, losing the hairs gained from its application in the first place.  

female hair loss is a very common form of shedding in women and can be treated with topical minoxidil.

Expected Results

Minoxidil tends work well for some patients while others may not respond well. Minoxidil responders often experience regrowth within a span of 3 – 6 months which tends to peak at around one year. However, many users tend to see a reduction in its efficacy over the long run. Minoxidil tends to be effective in the short term for most people while longer term studies show a reduction in response rate.

 

Pattern Hair Loss

Minoxidil has been originally approved for treating both male and female pattern hair loss. This study in men shows that the 5% solution resulted in an 18% increase in hair density which was a 45% higher rate of growth than the 2% solution after 48 weeks of application. Similarly, this study in women with pattern hair loss shows while both solution concentrations led to hair growth after 48 weeks, the 5% solution worked better for female pattern hair loss with an 26% increase in hair density. 

Alopecia Areata

Studies done on treatment of Alopecia Areata (AA) with topical monoxidil have suggested that monoxidil has some benefits in treating patients with this autoimmune disease.

As a standalone treatment, topical minoxidil can be used in mild cases of AA with some regrowth. However, for more severe cases of AA, minoxidil must be combined with other treatments. This study shows that a combination therapy of topical minoxidil with corticosteroids lead to a better regrowth rate than minoxidil alone. In another study, a 5% minoxidil solution lead to a higher rate of terminal hair regrowth than lower concentrations. 

Telogen Effluvium

While minoxidil is not recommended for the treatment of acute telogen effluvium, it has shown to be a promising option in combination with other medications for chronic telogen effluvium. Oral minoxidil has been shown to be effective in treating telogen effluvium and while the studies on topical minoxidil are limited, combination therapies with other appropriate medications is potentially helpful.   

Scarring Alopecia

Minoxidil as a combination therapy with other drugs has shown to be effective in the treatment of several types of scarring alopecias. Topical minoxidil in conjunction with oral finasteride or systemic steroids is shown to slow the progression of frontal fibrosing alopecia. Patients suffering from Traction Alopecia (especially in earlier stages) can also see significant regrowth through topical minoxidil as well.  

Anagen Effluvium

Anagen Effluvium is the most common cause of chemotherapy induced alopecia. Topical minoxidil has mixed results when it comes to chemotherapy induced hair loss. While this study showed that topical minoxidil can shorten the period of hairloss in chemotherapy patients, others have failed to show satisfactory results in different settings. Oral minoxidil however, was effective in inducing significant regrowth in this case of permanent chemotherapy induced alopecia following a 2 year treatment.

Body Hair Treatment

Topical minoxidil has been used to increase density in eyebrows and facial hairs. This study shows the effects of topical minoxidil versus placebo on eyebrow growth. A 16 week application of topical minoxidil lead to a significant growth and increase in hair diameter. This comparative study also showed similar improvements.  

Similar results are also seen in the application of 3% solution on facial hair in comparison to placebo in this studyTopical minoxidil shows potential in increasing hair density in eyebrow and facial regions with patients achieving satisfactory results.

Side Effects

Since topical minoxidil has limited systemic absorption, it’s most common side effect seems to be irritant contact dermatitis with the common symptoms of itching and scaling. This side effect is uncommon with its prevalence ranging from 2% – 6%. Given that a typical minoxidil solution contains other possible allergens such as propylene glycol, many patients with this side effect tend to be allergic to the propylene glycol and not the minoxidil itself. These patients can find alternative minoxidil solutions free from propylene glycol. However, in the unlikely case where the irritation still persists, then minoxidil is the irritant and the patient is not a suitable candidate for this treatment. 

Another rather rare side effect of topical minoxidil is excessive hair growth in unwanted areas. This is more common in women than men where the small amounts of absorbed minoxidil leads to facial, arm and leg hair growth. This growth is reversible after the discontinuation of application.

 

Precautions

 

This study showed that the activity of the sulfotransferase enzyme is reduced after a low dose aspirin use. Therefore aspirin use is expected to reduce the response to minoxidil.

Cats do not possess the enzyme to metabolize minoxidil and therefore are deathly allergic to it. There are many case reports of death in house cats caused by exposure to minoxidil (even through skin). Patients who own cats should take extra precaution to keep the solution away from the reach of their cats as well as avoiding contact between their cat and the minoxidil applied skin areas.

Patients who experience skin irritation after application of topical monixidil should switch to a propylene glycol free solution. If the irritation persists, they might be allergic to minoxidil itself in which case treatment must be discontinued.

Review Our Case Studies

To see the results of Minoxidil along with other treatment options, review our case studies and read about other patients success stories. 

You are a good candidate for Topical Minoxidil treatment if:

 

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Are suffering from any of the aforementioned forms of hair loss

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Willing to apply minoxidil twice daily over a life time

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Do not have an allergic reaction to the solution

REFERENCES
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