Minoxidil is a non-prescription drug that is used to reverse hair loss. So what happens during frequent minoxidil application? Let’s find out.
Hair Loss Fast Facts
An adult human loses approximately 50-100 hairs each day. Losing more than 125 hairs per day indicates excessive hair loss. An imbalance between the falling of hair and the growth of new hair leads to hair loss, also known as alopecia.
According to a survey conducted by the International Society of Hair Restoration Surgery (ISHRS) in 2014, hair loss affects almost 35 million men and 21 million women in the United States.
According to this survey, men tend to experience greater hair loss with increasing age. Receding hairline, wider hair parting, bald patches, loosen hair, and itchy skin is common manifestations of excessive hair loss.
Androgenetic alopecia or pattern hair loss is a common form of hair loss in males and females. Lifestyle changes, hair transplantation surgeries, and the use of medications are effective treatment options for excessive hair loss in androgenetic alopecia.
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What is Minoxidil?
Minoxidil was initially formulated as an oral drug to treat hypertension owing to its vasodilating properties. During the treatment, the majority of the patients complained of hypertrichosis or excessive hair growth.
Patients also reported growth of new hair in balding areas. The discovery of these novel properties led to the formulation of topical minoxidil for the treatment of androgenetic alopecia for male and female pattern hair loss.
Minoxidil is available in both 2% and 5% solution form as well as manufactured as minoxidil foam. Minoxidil is available in the market under the brand name Rogaine.
Minoxidil demonstrates the vasodilating effects by opening the potassium channels located in the muscular walls of these arteries. The potassium ions leave the cell, resulting in the relaxation of the muscles lining the arteries causing vasodilation.
Vasodilation of arteries improves blood flow and enhances the delivery of oxygen and essential nutrients for the nourishment of hair follicles. Studies also show that the fenestrations in the vessels increase with the application of minoxidil, which further improves the outflow of nutrients to the hair follicles.
The use of minoxidil nourishes the existing hair follicles, promotes new hair growth, and also maintains this growth.
The Active Ingredient of Minoxidil
The active ingredient responsible for the anti-hypertensive and hair growth-promoting effects of minoxidil is minoxidil sulfate. The hair follicles contain an enzyme known as phenol sulfotransferase that is responsible for minoxidil sulfation and the formation of minoxidil sulfate.
Individuals with higher activity of phenol sulfotransferase show better hair growth upon application of topical minoxidil as compared to ones who have lower enzyme activity.
Drugs including aspirin and salicylates are known to suppress the activity of phenol sulfotransferase. Reduced intake of these drugs during minoxidil treatment for hair loss demonstrated better results.
To understand the mechanism of action of minoxidil on hair growth, brief background knowledge of phases of hair growth can be useful. The human hair growth cycle consists of the following four phases:
Anagen – Growing Phase
Anagen or the growing phase is the longest phase of the hair growth cycle lasting for about three to five years. Approximately 90% of the scalp hair is in the anagen phase. The anagen phase of pubic and eyebrows hair is shorter than the scalp hair. In the anagen phase, the cells in hair follicles divide rapidly and give rise to a new hair shaft.
The length of the anagen phase is determined by the genetics of an individual. People with longer hair strands have hair follicles that spend relatively greater time in the anagen phase. After the anagen phase, signals direct the hair follicles to enter the catagen phase.
Catagen – Transition Phase
The catagen phase is a short transition phase that initiates at the end of the anagen phase. The catagen phase indicates the end of the period of active growth of hair.
The catagen phase is approximately two to three weeks long. In this phase of the hair growth cycle, the hair strands detach from the hair follicle, and the blood supply to the hair follicle decreases. The hair follicles shrink and the growth of hair slows however the hair strands remain in place.
Almost 5% of the scalp hair is in the catagen phase of the hair growth cycle. At the end of this phase, the hair enters the telogen phase.
Telogen – Resting Phase
The telogen or resting phase of the hair growth cycle lasts for almost three months. As indicated by its name, the hair in the telogen phase neither grows nor falls out from the hair scalp.
Approximately 10% to 15% of the scalp hair resides in the telogen phase. This phase indicates the release of existing hair and the start of new hair growth from the hair follicles. The telogen phase is followed by the exogen phase which is the final phase of the hair growth cycle.
Exogen – Shedding Phase
The exogen or shedding phase of the hair growth cycle is considered an extension of the telogen phase. After spending three months in the telogen phase, the hair strands fall out from the scalp. This process is further facilitated by the brushing and washing of hair.
Approximately 50 to 100 hair strands are shed during the exogen phase. The hair spends two to five months in the exogen phase while new hair strands grow from the hair follicles during this phase.
Minoxidil improves the growth of pre-existing hair and induces the growth of new hair from the hair follicles. Minoxidil influences two stages of the hair growth cycle – the anagen and the telogen phase.
The nitric oxide moiety of minoxidil sulfate acts as a nitric oxide agonist. This prolongs the anagen phase and stimulates the shedding of hair in the telogen phase. Individuals using minoxidil for hair growth may experience hair loss in the start owing to the effect of minoxidil on the telogen phase.
The shedding of hair is proportional to the potency of topical minoxidil. However, the hair is eventually replaced by newer and thicker hair present in the anagen phase. Minoxidil also shortens the telogen phase, thus reducing hair loss and maintaining the regrowth of hair.
How Long Does Minoxidil Take to Show Results?
We have a more in-depth article here: How Long Does Minoxidil Take To Work?
Topical minoxidil can be applied to the scalp in the form of foam or solution. Though 5% minoxidil solution causes greater hair shedding in the initial phase of hair loss treatment, it causes relatively better hair growth as compared to 2% minoxidil solution.
Minoxidil foam or solution should be applied on a clean and dry scalp in the affected areas. This is followed by gently rubbing the foam or solution onto the scalp and letting the scalp dry before styling the hair.
Minoxidil is converted to minoxidil sulfate by the phenol sulfotransferase enzyme present in the hair follicles. The active metabolite, minoxidil sulfate starts working immediately and promotes hair growth.
The visible effects take about four to six months to appear considering that the medication is used consistently. The increased time duration between the start of minoxidil and the appearance of results is due to two reasons – the hair shedding in the telogen takes around 8 weeks to subside and the hair follicles take time to reenter the anagen phase of the hair growth cycle.
With time the telogen phase shortens and hair shedding reduces along with the growth of thicker hair in the anagen phase. People suffering from androgenetic alopecia usually observe peak hair growth after one year of 2% and 5% minoxidil application.
Lower concentrations of topical minoxidil solution can be applied to maintain the regrowth of hair.
When Do You Need A Prescription for Minoxidil?
As compared to oral minoxidil which requires a prescription before usage, topical minoxidil foam or solution is an over-the-counter medication and can be used without a prescription.
However, one should consult a physician before using topical minoxidil to discuss the interaction of this medication with the existing medical conditions and drug history.
If an individual experiences irritation after the application of topical minoxidil, he or she should consult the doctor and obtain a prescription for oral minoxidil. Minoxidil is widely available online and in pharmacies.
Before and After Results of Minoxidil Application
The efficacy of minoxidil depends on a variety of factors which are summarized as follows:
- People who tend to have greater activity of phenol sulfotransferase observe better results with the use of topical minoxidil as opposed to people who are genetically susceptible to decreased activity of the enzyme.
- The duration of topical minoxidil application determines the effectiveness of the medication. Individuals who apply minoxidil foam or solution consistently for up to a year tend to experience better hair growth and significantly reduced hair loss. This is in contrast to patients who are not consistent with the application of topical minoxidil.
- Existing hair condition at the time of topical minoxidil usage determines the action of minoxidil on hair growth. People with thinner hair and greater bald patches do not get desired results from minoxidil usage as compared to individuals who have denser hair and lesser bald patches.
- The use of topical minoxidil is limited in individuals who are sensitive to this medication. Such people are prescribed oral minoxidil.
What Are The Side Effects of Minoxidil Application?
Use of topical minoxidil may have the following negative effects:
- Skin irritation is one of the most common side effects of topical minoxidil application. This presents as skin rash and burning sensation after applying the solution or foam.
- Acne, excess facial hair growth or hypertrichosis, and swelling of the face are rare side effects of minoxidil use.
- The application of minoxidil also causes excessive hair loss and inflammation of the hair roots in the early phase of the treatment.
Excessive use of minoxidil manifests as dizziness, abnormal pulse, headache, chest pain, visual impairment, swelling, and numbness of hands and feet. Edema caused by minoxidil can also result in excess and rapid weight gain.
If an individual is experiencing these side effects, he or she should consult the physician immediately. The use of minoxidil should be reduced or discontinued depending on the severity of the side effects.
Owing to the negative effects associated with the application of topical minoxidil, this should not be used during pregnancy and breastfeeding. People younger than 18 years of age should also not use minoxidil.
If you are not eligible to use minoxidil or if you’re afraid of its side effects, there are alternatives to minoxidil you can look into.
Is Minoxidil Widely Available?
Minoxidil is available in two forms. Oral minoxidil is used as an anti-hypersensitive drug that is obtained using a prescription. Topical minoxidil is an over-the-counter medication that does not require a prescription, however, consulting a physician before using the drug is significant for allergies, drug interactions, previous medical history, and existing disorders.
Topical minoxidil is available in the form of minoxidil foam as well as 2% and 5% minoxidil solutions. The drug is sold with the brand name Rogaine. This drug is approved by FDA and is available online, can be obtained from retailers, and is commonly found in pharmacies such as CVS Health, Walgreens, Express Scripts, Walmart, and Rite Aid.
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- Liu, Y., Jiang, Ll., Liu, F. et al. Comparison of low-level light therapy and combination therapy of 5% minoxidil in the treatment of female pattern hair loss. Lasers Med Sci 36, 1085-1093 (2021). https://doi.org/10.1007/s10103-020-03157-1
- Panchaprateep, R., Lueangarun, S. Efficacy and Safety of Oral Minoxidil 5 mg Once Daily in the Treatment of Male Patients with Androgenetic Alopecia: An Open-Label and Global Photographic Assessment. Dermatol Ther (Heidelb) 10, 1345-1357 (2020). https://doi.org/10.1007/s13555-020-00448-x