Topical Minoxidil Side Effects: What can I expect?

The Side effects of topical minoxdil:

Minoxidil is FDA approved for the treatment of androgenetic alopecia in both men and women. The drug has been studied for treating hair loss for over 40 years but was formally been FDA approved in 1987.

Minoxidil is a blood pressure medication which remarkably also stimulates hair growth. Minoxidil has about 10 different mechanisms of action on hair and the precise reason in stimulates hair growth is still somewhat of a mystery. Most researchers feel that it is the effect of minoxidil on potassium channels inside hair follicles that is responsible for its mechanism of action.

Common and Uncommon Side effects of Minoxidil

Minoxidil has a number of potential side effects. The most common five side effects are headaches, dizziness, heart palpitations, hair shedding when starting and increased hair growth on the face (particularly for women)

Other side effects are less common and rarely reported but could possibly be increased when using minoxidil. Good studies of these rare side effects have not been done and were not reported in the original clinical trials. These include such issues as swelling in the ankles, ringing in the ears, among other rare side effects.

Minoxidil and Collagen: Are the Anti-fibrotic Effects of Minoxidil Actually a Good Thing?

There is currently a great buzz in the internet world that minoxidil affects collagen and promotes aging. The theory is that by reducing collagen synthesis, facial aging is sped up. To date, there is no good evidence either in the medical literature or in my practice that minoxidil promotes aging. More reserach is certainly needed but it’s not a commonly reported effect in any way whatsoever.

As for affecting collagen synthesis- minoxidil probably does affect collagen synthesis. The problem with the unsubstantiated claims on the internet is that nobody has dared to offer the potential explanation that the minoxidil-induced reduction in collagen synthesis might actually a good thing.

The lay public forgets (or was simply unaware in the first place) that androgenetic alopecia is associated with significant increases in perifollicular fibrosis. That’s right - male and female balding is associated with INCREASED collagen production in the form of ‘fibrosis’ around hair. And this is not a good thing as the infalmmation and scarring around hairs only serves to speed up the miniaturization process and speed up the destruction of the delicate stem cells. It seems, based on 2006 studies by Yoo and colleagues that a growth factor known as TGF beta is responsible for this increase in collagen production. A variety of studies suggest that minoxidil has the potential to REDUCE TGF beta levels and in turn REDUCE the likelihood of further fibrosis.

It’s premature to jump to conclusions that minoxidil promotes facial aging. If it does, it’s rare - likely because not enough minoxidil reaches the facial skin. But minoxidil probably does affect collagen and that’s most likely a really really wonderful thing rather than a bad thing because it suppresses the formation of more and more scar tissue around hairs that ultimately destroy stem cells. Patients worried about the small unproven risk of facial aging should not of course use the product.


Yoo et al. Perifollicualr fibrosis: pathogenic role in androgenetic alopecia. Biol Pharm Bull 2006

Messenger AG et al. Minoxidil: mechanisms of action on hair growth. . Br J Dermatol 2004.

Dr. Jeff Donovan is a Canadian and US board certified dermatologist specializing exclusively in hair loss. To schedule a consultation, please call the Whistler office at 604.283.1887

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