Both of these medications have been around for decades, with both widely used to treat male pattern baldness, or androgenetic alopecia.
But do either of them really work? If so, which of them is the most effective option for stopping hair loss and regrowing hair?
We’ve also talked about how you can use minoxidil and finasteride, either individually or as a combination treatment, to stop hair loss and grow a fuller, thicker head of hair.
Minoxidil and finasteride are two of the most popular hair loss treatments on the market. Both treatments are backed up by scientific research, although there are several major differences between the two drugs.
The biggest difference between minoxidil and finasteride is the dosage form each medication takes.
Minoxidil is a topical medication that’s available as a liquid solution or foam. It’s formulated for use directly on your scalp and works by promoting hair growth locally.
Finasteride, on the other hand, comes in tablet form. Instead of working locally to promote hair growth on your scalp, it has a more systemic effect throughout your body.
Minoxidil is a vasodilator that’s available as an over-the-counter medication. Researchers think that minoxidil works by widening the blood vessels inside your scalp and increasing the rate of blood flow to your hair follicles.
It also helps to stimulate hair growth by lengthening the anagen, or growth, phase of the hair growth cycle.
Technically, minoxidil doesn’t stop hair loss. Instead, it actively promotes the growth of hair by causing hairs in a resting state (known as the telogen phase) to shed and replacing them with new hairs in the growing (or anagen) phase.
Because minoxidil interrupts your hair growth cycle, it may cause you to shed slightly more hairs during the first few months of use.
This is a normal side effect that will pass with time. As the telogen hairs are replaced with new anagen hairs, your hair may start to take on a thicker, denser appearance.
Our guide to the hair growing process explains this multi-phase cycle in more detail, as well as how treatments like minoxidil can fit into the process.
If you’ve searched online for information about treating hair loss, you may have read that male pattern baldness -- the most common form of hair loss in men -- occurs due to the effects of an androgen hormone called dihydrotestosterone, or DHT.
Over time, if you’re genetically predisposed to hair loss, DHT can miniaturize your hair follicles and stop them from growing new hairs. This process often starts by affecting your hairline and vertex scalp, or crown.
You can learn more about DHT and its effects on your hair in our guide to DHT and male hair loss.
Minoxidil doesn’t appear to have any effect on your DHT levels, meaning it won’t “shield” your hair from the effects of DHT.
However, for many men, it can promote hair growth and make areas of your scalp with thinning hair look thicker, fuller and less affected by hair loss.
Finasteride belongs to a class of medications called 5-alpha-reductase inhibitors. As a hair loss treatment, it works by blocking the effects of the 5-alpha-reductase, which is responsible for the conversion of testosterone into DHT within your body.
As we mentioned above, DHT is the primary hormone that’s responsible for miniaturizing your hair follicles and causing male pattern baldness.
By stopping testosterone from converting into DHT, finasteride reduces your DHT levels and stops this hormone from binding to your hair follicles and causing damage.
While minoxidil works more like a growth agent for your hair, you can think of finasteride as a shield that protects the hair follicles in your scalp from being exposed to the effects of DHT in the first place.
Finasteride is best known for its ability to prevent male pattern baldness from worsening and protect your existing hair.
Because it takes quite a lot of time for DHT to damage your hair follicles, finasteride can even cause mild regrowth in patches of hair that are starting to thin.
Put simply, yes. Both minoxidil and finasteride have been scientifically proven to help either stop hair loss and, for some men, promote hair growth.
Finasteride has been proven to work in numerous studies. In a study published in the Journal of the American Academy of Dermatology in 1998, researchers looked at the effects of finasteride on more than 1,500 men with male pattern hair loss.
They found that finasteride improved hair growth on the scalp, with an average increase of more than 15% after two years of treatment.
Numerous other studies have also found that finasteride helps to stop hair loss in most men and stimulate hair growth for many.
In a five-year study of finasteride published in the European Journal of Dermatology, men given finasteride saw improvements in scalp hair growth and reduced progression of hair loss.
An even longer 10-year study conducted in Japan found that daily use of finasteride prevented male pattern baldness from worsening in more than 99 men and caused improvements in hair growth in more than 91 percent of study participants.
In short, for most men, finasteride is effective at preventing hair loss and stimulating the growth of new hair.
There are also several reputable studies showing that topical minoxidil is effective at preventing hair loss and promoting hair growth.
In a 12-month study carried out in Germany, researchers found that 97.1 percent of balding men who used minoxidil saw an improvement in hair growth or no worsening of their hair loss.
Of the men that participated in the study, 84.3 percent rated minoxidil as either “very effective,” “effective” or “moderately effective” as a hair loss treatment.
A review of minoxidil published in the journal Drug Design, Development and Therapy analyzed several studies of minoxidil and concluded that it offers “remarkable benefits” to people affected by hair disorders.
In short, like finasteride, minoxidil is backed up by real, reputable scientific studies that show it’s effective.
Minoxidil and finasteride come in very different dosage forms. To get the best results from either medication (or both medications together), it’s important to use it at the recommended dosage.
A normal dosage of minoxidil is 1ml of liquid solution applied directly to the scalp two times per day, typically morning and night. Our guide to applying minoxidil explains how you should use this medication for optimal results.
A normal dosage of finasteride for male pattern baldness is 1mg per day, either with or without food.
Minoxidil and finasteride are both well-studied, well-tolerated medications that are safe for most people.
However, like other medications, minoxidil and finasteride both have potential side effects that may affect you if you use these medications to treat hair loss.
Common side effects of minoxidil include itching, dryness, scaling, flaking, burning and irritation that can affect your scalp.
These side effects may occur after you start using minoxidil. If they are persistent, it’s important to talk to your healthcare provider for more information.
Because minoxidil affects your hair’s growth cycle, you may notice more hair loss than usual in the first few months of treatment. As we’ve explained in our full guide to minoxidil side effects, this is a temporary issue that usually disappears over the course of several months.
Although uncommon, finasteride can cause sexual side effects, as well as side effects that may affect your mood.
For example, a small percentage of men who use finasteride develop sexual issues such as a reduced level of sexual desire, decreased ejaculatory volume, testicular pain or discomfort and erectile dysfunction (ED). Finasteride may also contribute to depression.
Although side effects like a decreased libido and ED can sound alarming, it’s important to keep in mind that they’re not very common.
For example, according to data from the FDA, even when finasteride is used at a 5mg dosage (five times the recommended dosage for hair loss), the rate of men who experience long-term erectile dysfunction is no different from that of a non-therapeutic placebo.
Our guide to the side effects of finasteride explains these issues and their prevalence amongst finasteride users in more detail.
Studies show that minoxidil and finasteride are safe to take together. In fact, many studies have looked specifically at the effects of minoxidil and finasteride as a combination treatment for hair loss in men.
Interestingly, some of these studies have found that finasteride and minoxidil are more effective when used together than they are separately.
A 2015 study published in the Indian Dermatology Online Journal found that regular use of both finasteride and minoxidil together helped to maintain a good hair density level.
Interestingly, this study used a topical version of finasteride, rather than the more common oral finasteride tablets.
A larger study published in the journal Dermatologic Therapy looked at the effects of finasteride and minoxidil used at the same time to treat male pattern baldness.
After 12 months of treatment, 94.1 percent of the men who used finasteride and minoxidil at the same time showed improvements, compared to 80.5 percent and 59 percent of the men treated with finasteride or minoxidil alone, respectively.
Finasteride and minoxidil work through different mechanisms -- minoxidil as a topical vasodilator and finasteride as a 5-alpha-reductase inhibitor that targets DHT.
Since they work in different parts of the body, there’s no risk in taking them together. In fact, as the studies above show, you’ll likely experience better results by using finasteride and minoxidil together than by only taking one medication to treat hair loss.
You should always check for potential drug interactions before you start any hair loss treatment, including medications like minoxidil and finasteride.
If you use any other medications, it’s important to talk to your healthcare provider to check that it’s safe to continue using these medications while you use minoxidil and/or finasteride to treat hair loss.