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Minoxidil is an oral medication that was initially approved by the FDA in the 1970s to treat severe and treatment-resistant hypertension (high blood pressure). Doses used for the treatment of hypertension range between 10mg and 40mg daily. At this dose, patients who were taking minoxidil for blood pressure control were noted to have “hypertrichosis” (increased hair growth on face and body) as a side effect. Minoxidil works to increase hair growth by causing a shortening of the telogen (resting) phase and lengthening of the anagen (growth) phase of the hair cycle, which increases the hair follicle diameter and length.

Topical versions of minoxidil (brand name: Rogaine) have been used for decades to help slow genetic thinning, but daily compliance with the application is often a barrier to continued use. Over the past 5 years, low doses of oral minoxidil have been used “off-label” to help patients with androgenetic alopecia who prefer daily oral administration over topical application. Recently there has been a significant increase in the interest for the oral formulation due to a NY Times article on oral minoxidil titled, “An Old Medicine Grows New Hair for Pennies a Day…”

The oral form may be more effective, but this has not yet been documented in controlled studies. For patients already taking topical minoxidil (Rogaine), adding the oral formulation (rather than switch from topical to oral) will give the best results.

The main reasons to consider oral minoxidil are:

  1. It is probably more effective than topical – when either formulation is used alone
  2. When both forms of topical medication irritate the scalp and cannot be tolerated i.e., the solution and the foam
  3. When it is too inconvenient or messy to use the topical version. This is particularly important for women who wash their hair infrequently.

Early studies have shown that oral minoxidil can be an effective treatment for male and female patients with androgenetic alopecia. Minoxidil doses used for hair loss are lower than those used previously to treat hypertension. Most patients will tolerate the medication without major side effects.

For genetic thinning in women, doses ranging between 0.25mg and 1.25 mg seem to be the most effective and safe. In addition, combination with 25mg spironolactone may increase the effectiveness and limit side effects by reducing fluid retention that can be seen with minoxidil. In men, genetic thinning is often treated with 2.5mg or 5mg of oral minoxidil daily. Spironolactone is contraindicated in men. Women who are pregnant, or are planning to get pregnant, should not take spironolactone.

The most common side effect experienced with low-dose oral minoxidil is hypertrichosis (excess hair around the face and/or body). This hypertrichosis is often mild and manageable in most patients, especially in men. Other less common side effects include low blood pressure (that can result in dizziness), fluid retention (that would cause ankle swelling or weight gain), and EKG changes (that might be experienced as palpitations i.e., irregular heartbeats). A rare complication, almost exclusively seen at the higher doses used to control blood pressure, is fluid accumulation around the heart (pericardial effusion).

Shedding may be noted during the first few months after starting therapy. It can even happen if someone is already on the topical form. It is important not to discontinue the medication for this reason. The benefits of minoxidil will stop if the medication is discontinued. Over the two to six months following stopping, the hair loss pattern will return to the state that it would have been reached if the medication had never been used. Because of this, patients that consider using minoxidil for hair loss should expect to be on the medication long-term.

Finally, minoxidil either in its topical or oral form, is not a substitute for finasteride (Propecia) which is far more effective in the treatment of hair loss. Some patients may choose one or the other due to their different side effect, but the two drugs are synergistic and will give the best result when used together.


New York Times: Health 8/18/2022 “An Old Medicine Grows New Hair for Pennies a Day, Doctors Say”

Updated: 2022-09-19 | Published: 2021-05-24