Stimulating Hair Growth with Minoxidil

The first FDA-approved medication for the treatment of hair loss was topical minoxidil, also known by the brand name Rogaine. Rogaine is a topical solution that’s applied directly to the scalp. Originally available only with a doctor’s prescription, it’s now available over-the-counter as both Rogaine and generic minoxidil solution, and it comes in concentrations of 5 percent for men and 2 percent for women. Recently, Rogaine developed a new minoxidil formulation in a 5 percent topical foam. This product is less greasy and easier to apply for some people.

How minoxidil works?

Before minoxidil was available topically, it was an oral blood pressure medication. Doctors observed that many people taking oral minoxidil not only had a decrease in blood pressure but began growing body hair as well. It was reasoned that applying minoxidil directly to a bald scalp may cause hair to grow in this area without producing the side effects of the oral medication. Researchers developed a topical formulation, and studies showed modest hair growth on the scalp.

Just how minoxidil works in hair growth is unknown. The drug is a vasodilator (vasodilators cause the blood vessels to dilate, or expand) and may increase the flow of blood to the hair follicle, but how this relates to hair loss is unclear. In addition, minoxidil also increases the duration of the hair follicle growth cycle and improves the quality of the hair by increasing the diameter and length of fine, miniaturized hair.

How effective is minoxidil and on which areas of the scalp?

The original studies on minoxidil were performed on the crown of the head, so there’s a misconception that it only works in this area. Although minoxidil may work best in the crown area, it also works to a lesser degree in other areas as long as there’s some fine (miniaturized) hair (such as at the front of the scalp). However, it doesn’t work if the area is totally bald.

The greatest benefit from minoxidil is visible between six months to two years from the beginning of treatment. After this time, you see a gradual decrease in effectiveness, so you’ll continue to lose hair, but at a slower rate than if you weren’t on the drug.

The effectiveness of minoxidil to treat men with pattern hair loss has been investigated since the mid-1980s and is well established. Even though both 5 percent and 2 percent solutions have been shown to decrease hair loss and increase hair, the 5 percent solution seems to work better.

If you stop using minoxidil, the effects wear off within three months, and the previous pattern of hair loss resumes. When you restart it, you generally don’t regain the hair that was lost, so it’s best not to stop and start the mediation but rather to use it regularly.

Does minoxidil work for women?

Yes, minoxidil works for women with pattern hair loss, but only the 2 percent concentration of minoxidil has been approved for their use. In 1994, a study was conducted in which 256 women with androgenic alopecia used 2 percent minoxidil twice daily for 32 weeks. At the end of the study, the investigators found that 60 percent of the patients in the 2 percent minoxidil group reported new hair growth compared with 40 percent of the patients in the placebo group.

The investigators concluded that minoxidil is an effective treatment for pattern hair loss in women but that it doesn’t work on all patients.

Although the 2 percent minoxidil solution is the only approved dose in women, there’s evidence that the 5 percent solution may be superior. In 2004, a study with 381 female patients with pattern hair loss was conducted comparing 5 percent minoxidil with 2 percent minoxidil. Both strengths were shown to help regrow hair, but the 5 percent topical minoxidil group demonstrated superiority over the 2 percent group.

What are minoxodil’s side effects?

By far the most common side effect of topical minoxidil is local irritation, although the foam formulation is much less irritating than the original version.

Another side effect sometimes seen in women is the development of facial hair. Although this may decrease when the medication is discontinued, at times the hair may need to be removed after treatment with either electrolysis or lasers. To reduce the chances of this problem (although you can’t eliminate it entirely), you should be careful when applying minoxidil and try to avoid the medication dripping down onto the temples and forehead, unless, of course, a hairy forehead is the look you’re going for! (Although the 2 percent solution is standard for women, there’s a significantly greater incidence of this side effect when the 5 percent solution is used.)

Female patients also seem to be more sensitive to the potential systemic side effects of minoxidil in decreasing blood pressure (a condition called hypotension). Rarely women may get lightheaded (a symptom of low blood pressure) from topically applying minoxidil. Women also have an increased risk of developing allergic skin reactions on the scalp.