Original articleSafety of low-dose oral minoxidil for hair loss: A multicenter study of 1404 patients
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.
References (28)
- et al.
Dose-response study of topical minoxidil in male pattern baldness
J Am Acad Dermatol
(1986) - et al.
Safety and efficacy of topical minoxidil in the management of androgenetic alopecia
J Am Acad Dermatol
(1987) - et al.
Effectiveness and safety of low-dose oral minoxidil in male androgenetic alopecia
J Am Acad Dermatol
(2019) - et al.
Very-low-dose oral minoxidil in male androgenetic alopecia: a study with quantitative trichoscopic documentation
J Am Acad Dermatol
(2020) - et al.
Efficacy and safety of very-low-dose oral minoxidil 1.25 mg in male androgenetic alopecia
J Am Acad Dermatol
(2020) - et al.
Minoxidil 1 mg oral versus minoxidil 5% topical solution for the treatment of female-pattern hair loss: a randomized clinical trial
J Am Acad Dermatol
(2020) - et al.
Oral minoxidil treatment for hair loss: a review of efficacy and safety
J Am Acad Dermatol
(2021) Treatment of monilethrix with oral minoxidil
JAAD Case Rep
(2016)- et al.
Characterization and management of hypertrichosis induced by low-dose oral minoxidil in the treatment of hair loss
J Am Acad Dermatol
(2021) 26 - Central sympathetic agents and direct vasodilators
Minoxidil
Loniten (Minoxidil Tablets USP) [package insert]
Minoxidil
South Med J
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2023, Journal of the American Academy of DermatologyCitation Excerpt :Side effects include dizziness and postural hypotension (Table II).17-19,21,23,24-27,32-35,38,39,42,46,48,50-52 Hypertrichosis is most common, especially at 5 mg daily, but generally mild and may be less concerning in transmasculine patients, depending on desired gender expression.18,21,23,51 Patients should be warned about temporary increased hair shedding lasting 3-6 weeks.18,19
Medical and procedural treatment of androgenetic alopecia – Where are we?
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Funding sources: None.
IRB approval status: Approved.
Reprints not available from the authors.