This observation led to its topical formulation, which has become the first-line treatment of male and female pattern hair loss.
Mechanism of action
Minoxidil prolongs the anagen phase of the hair follicle and transforms the miniaturised follicles into terminal hair follicles.
The precise mechanism of action is still unclear; some hypotheses include enhanced vasodilatation and proliferative, anti-androgenic and anti-inflammatory effects.
Several meta-analysis studies have confirmed the high quality of evidence for the use of minoxidil to treat androgenetic alopecia -AGA– in both sexes.
In one study, dermatologists evaluated the effectiveness of minoxidil 5% solution in 984 men with male-pattern hair loss.
After one year, they reported that hair loss areas of the scalp had become smaller in 62% of the patients, unchanged in 35.1% and more significant in 2.9%.
Regarding minoxidil effectiveness in stimulating hair regrowth, the investigators found it very effective in 15.9% of patients, effective in 47.8%, moderately effective in 20.6% and ineffective in 15.7%
In men, the recommended dosage for minoxidil is 1 mL twice daily for the 5 % solution.
The dosage for minoxidil 5 % foam is half a capful twice daily.
For women, the recommended dosage is 1 mL of 2 % minoxidil solution twice daily or half a capful of the 5 % foam formulation once a day.
Both formulations should be applied on dry scalp and left in place for at least four hours.
Massage is not needed. It is advisable to apply it two hours before bed to allow adequate time for drying and avoid it spreading on the face during sleep.
Some patients notice a transitory increase in hair shedding at the beginning of treatment. However, this is just a sign of minoxidil efficacy. It indicates that telogen follicles are re-entering the anagen phase. It usually lasts for a few weeks.
Patients should be treated for at least six months before assessed by a hair restoration physician and treatment should be prolonged indefinitely to maintain efficacy.
The most common adverse effects of minoxidil include scalp dryness, contact dermatitis and facial hypertrichosis.
Minoxidil solution containing propylene glycol can cause skin irritation or allergy. Patients may switch to the foam formulation in case of skin irritation as it does not contain propylene glycol.
Hypertrichosis is reported more frequently in women than in men. Still, it is unclear whether this occurs because it is genuinely more common or just more noticeable. It usually resolves 1–3 months after drug discontinuation.
Minoxidil is not advised for women who are pregnant. Since minoxidil is excreted into breast milk in very low concentrations and no adverse effects have been reported in infants, the American Academy of Pediatrics considers minoxidil compatible with lactation.
Minoxidil discontinuation will cause acute hair shedding after 3–4 months.
To date, topical minoxidil is the mainstay treatment for androgenetic alopecia.
If you are looking into hair restoration solutions, contact us. Dr Bonaros can assess your case, perform a reliable diagnosis and provide you with a realistic and comprehensive treatment plan. He will also monitor the effectiveness of the medical therapy clinically and suggest additional medical and surgical options to augment the benefits of minoxidil.
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