What is the recommended dosing of minoxidil (2% or 5% solution) for the treatment of hair thinning?

From the Guidelines

For the treatment of hair thinning, the recommended dosing of minoxidil is 1 mL of the 5% solution applied twice daily to the affected areas of the scalp, as it has been shown to be more effective than the 2% solution, particularly in combination with other treatments like PRP 1. The 5% solution is generally considered more effective for both men and women, although women can use either concentration. It's essential to apply the medication to a dry scalp and allow it to dry completely before using styling products or going to bed. Results typically take 4-6 months of consistent use to become noticeable, and continued application is necessary to maintain any hair growth achieved. If treatment is discontinued, any new hair growth will likely be lost within 3-4 months. Minoxidil works by prolonging the growth phase of hair follicles and increasing blood flow to the scalp, which helps deliver nutrients to hair follicles. Some key points to consider when using minoxidil for hair thinning include:

• Applying the solution twice daily for optimal results
• Using the 5% solution for better efficacy, especially when combined with PRP 1
• Allowing the solution to dry completely before styling or sleeping
• Being patient, as results may take several months to become noticeable
• Continuing treatment to maintain any achieved hair growth Common side effects may include scalp irritation, unwanted hair growth in adjacent areas, and initial increased shedding in the first few weeks of treatment, which is actually a sign the medication is working. It's also worth noting that combining minoxidil with other treatments, such as PRP, may lead to even better outcomes, as shown in studies where PRP with topical minoxidil was the most effective treatment modality 1.

From the FDA Drug Label

Minoxidil topical solution 5% is a clear, light amber liquid medication containing 5% minoxidil for use only on the scalp to help regrow hair in men. ...make sure you get the medicine directly to the scalp and apply it twice a day, every day. Results may be seen as early as 2 months with twice daily use. For some men, it may take at least 4 months for results to be seen

The recommended dosing of minoxidil for the treatment of hair thinning is twice a day, every day, with a 5% solution for men. It is essential to apply the medicine directly to the scalp to see results, which may be visible as early as 2 months with consistent use 2.

From the Research

Minoxidil Dosing for Hair Thinning

• The recommended dosing of minoxidil for the treatment of hair thinning is available in 2% or 5% solution, with both being FDA-approved for androgenetic alopecia (AGA) in men and women 3.
• Topical minoxidil (5% foam, 5% solution, and 2% solution) acts through multiple pathways, including as a vasodilator, anti-inflammatory agent, inducer of the Wnt/β-catenin signaling pathway, and antiandrogen 3.
• A five-year study found that 2% minoxidil exhibited peak hair growth in males at year one, with a decline in subsequent years, while the 5% solution and foam were not significantly different in efficacy from the 2% solution 3.

Comparison of Minoxidil Solutions

• The 5% solution and foam were found to be not significantly different in efficacy from the 2% solution in terms of hair regrowth in both frontotemporal and vertex areas 3.
• Oral minoxidil 5 mg/day was found to be significantly more effective than topical 5% and 2% in male AGA, while low-dose 0.5-5 mg/day may also be safe and effective for female pattern hair loss and chronic telogen effluvium 3, 4.

Safety and Efficacy of Oral Minoxidil

• Oral minoxidil has been found to be an effective and well-tolerated treatment alternative for healthy patients having difficulty with topical formulations, with a good safety profile and infrequent systemic adverse effects 5, 6.
• A multicenter study of 1404 patients found that the most frequent adverse effect of low-dose oral minoxidil was hypertrichosis (15.1%), while systemic adverse effects were infrequent and only 1.7% of patients discontinued treatment owing to adverse effects 6.