Exact mechanism of hair growth stimulation remains unknown. The Vasodilating action of Minoxidil in increasing local blood supply does not pay a role.
Recent studies suggest that Minoxidil may have 2 actions :
Opens and stimulate a ATP dependent-potassium channels in human hair follicles
Upregulates the vascular endothelial growth factor (VEGF) and prostaglandin endoperoxide synthase-I, which are involved in hair growth
Dosage
Applied once to twice daily
5% topical minoxidil is better than 2%
Efficacy
Minoxidil causes reversible hair growth when used for 4 weeks. Price’s 1999 study over 96 weeks in men showed the followings :
An increase in hair weight for those treated with minoxidil. The controlled group without using minoxidil continued to lose hair
Once treatment is stopped hair weight will be lost to the extent as if they had never been treated at all
A "saturation effect" with minoxidil - strength higher than 5% unlikely to have any addition effect
In Men
45% more hair growth
Earlier hair growth
Increase in hair diameter
In Women
A significant increase in terminal hair counts in the 5% group
Patients in the 5% group rated better in results
Critical Rescue Hair Size - Dr. Van Neste showed that over a 2 year period :
Finasteride could not return vellus hair to terminal hair
Effect is only possible for thick hair > 0.04mm diameter
Uses & Recommendations
May take up to 4 months to see any effect
May have a temporary increased shedding of hair about 3 to 5 weeks after the start of treatment. The hair shed is part of the natural cycle and is normal
Ideally used for a year before assessing efficacy
Minoxidil has no effect on the underlying hormonal cause in androgenetic alopecia.
Once the drug is stopped, hair loss will resume. It's positive effects are at best temporary and long-term results are somewhat disappointing
The American Hair Loss Association does not recommend minoxidil as the first line for men with AGA. Used when patient is not responding favorably to finasteride, or would prefer combined therapy
Side Effects
Minoxidil topical solution is safe. Absorption through skin is low
1 in 20 users will develop skin irritation, a higher incidence with the 5% solution rather than the 2%
Increase of facial hair is mainly seen in women. This effect lessens or even disappears after a year of continued use. It is reversible and goes away 1 to 6 months after the drug is discontinued
Warnings
Do not start minoxidil if you have no intention to use continuously!
