Original article
Safety of low-dose oral minoxidil for hair loss: A multicenter study of 1404 patients

https://doi.org/10.1016/j.jaad.2021.02.054Get rights and content

Background

The major concern regarding the use of low-dose oral minoxidil (LDOM) for the treatment of hair loss is the potential risk of systemic adverse effects.

Objective

To describe the safety of LDOM for the treatment of hair loss in a large cohort of patients.

Methods

Retrospective multicenter study of patients treated with LDOM for at least 3 months for any type of alopecia.

Results

A total of 1404 patients (943 women [67.2%] and 461 men [32.8%]) with a mean age of 43 years (range 8-86) were included. The dose of LDOM was titrated in 1065 patients, allowing the analysis of 2469 different cases. The most frequent adverse effect was hypertrichosis (15.1%), which led to treatment withdrawal in 14 patients (0.5%). Systemic adverse effects included lightheadedness (1.7%), fluid retention (1.3%), tachycardia (0.9%), headache (0.4%), periorbital edema (0.3%), and insomnia (0.2%), leading to drug discontinuation in 29 patients (1.2%). No life-threatening adverse effects were observed.

Limitations

Retrospective design and lack of a control group.

Conclusion

LDOM has a good safety profile as a treatment for hair loss. Systemic adverse effects were infrequent and only 1.7% of patients discontinued treatment owing to adverse effects.

Introduction

Minoxidil is a potent arteriolar vasodilator that was approved by the US Food and Drug Administration for the treatment of severe refractory hypertension in 1979.1,2 For patients aged >12 years, the dosage range is usually between 10-40 mg/day, with a maximum recommended dose of 100 mg.2,3 Minoxidil has a duration of action of approximately 24 hours despite having a plasma half-life of 4.2 hours,2,3 suggesting extravascular accumulation.4 Minoxidil sulfate, the biologically active metabolite of minoxidil, lowers blood pressure by opening sarcolemmal adenosine triphosphate-sensitive potassium channels in vascular smooth muscle cells.5

Oral minoxidil has dose-dependent predictable side effects at doses of 10-40 mg, including postural hypotension, fluid retention, tachycardia, pericarditis, and nausea.2 However, the most common adverse effect is hypertrichosis, which occurs in approximately 80% of patients.2 Based on this serendipitous adverse effect, topical minoxidil was developed in 1987 for male and female pattern hair loss.6,7 The precise mechanism through which minoxidil promotes hair growth is unclear. Minoxidil shortens the telogen phase of the hair growth cycle, thus causing premature transition to anagen.1 It also prolongs anagen, resulting in increased hair length and diameter. The initial hair growth-promoting effects of minoxidil occur after approximately 2 months, with maximal effects observed at 4 months.1

Low-dose oral minoxidil (LDOM) (0.25-5 mg/day) has been used off label to treat various forms of alopecia.8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 The use of LDOM for the treatment of hair loss has significantly increased in the last few years for several reasons: (1) many patients find oral administration more convenient than the topical application of a lotion or foam; (2) topical application is operator-dependent, ie, some parts of the scalp may be missed in those with widespread alopecia; and (3) LDOM circumvents the local side effects associated with topical minoxidil such as irritation and allergic contact dermatitis.22 Nevertheless, the major concern of oral administration is the potential risk of systemic adverse effects. Although published studies of LDOM for hair loss have demonstrated a favorable safety profile,8,9,13,14 the number of patients evaluated in these studies is generally low, and therefore, infrequent adverse effects may not have been detected. The objective of this study was to investigate the safety of LDOM for hair loss in a large cohort of patients.

Section snippets

Methods

A retrospective, multicenter, and descriptive study including 10 centers from 6 different countries was designed. Patients treated with LDOM for ≥3 months for hair loss of any cause were included. Epidemiological and safety data were collected. In patients who developed adverse effects, the type and time to development of the adverse effect, in addition to the need to withdraw or adjust the dose of LDOM, were also recorded. We analyzed the above parameters for each dose in patients who received

Results

A total of 1404 patients (943 women [67.2%] and 461 men [32.8%]) with a mean age of 43 years (range 8-86) were included. The most common indication for LDOM was androgenetic alopecia (82.4%), followed by telogen effluvium (4.8%), alopecia areata (3.8%), frontal fibrosing alopecia (2.8%), lichen planopilaris (2.5%), and fibrosing alopecia in a pattern distribution (1.8%). LDOM was the only systemic therapy in 20.8% of patients. Three hundred and thirty-nine patients received a fixed dose regimen

Discussion

To our knowledge, this research represents the largest study on the safety of LDOM for the treatment of patients with hair loss disorders. Since the first report of its use in 2 women with monilethrix in 2016,19,21 LDOM has been widely used for various types of alopecia,22 especially male10,16 and female pattern hair loss.13,14

LDOM was found to be well-tolerated in 2 recent systematic reviews investigating its effectiveness and safety in patients with hair loss.15,16 The most frequent adverse

Conflicts of interest

None disclosed.

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Funding sources: None.

IRB approval status: Approved.

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