Medically reviewed by Vicky Davis, FNP
Written by Our Editorial Team
Last updated 6/13/2021
Losing a few hair strands to the shower drain is a fairly accepted part of life.
But when these hairs multiply from just a few strands, to even more worrying clumps in your hairbrush, you may be suffering from hair loss.
While a number of factors may be responsible for women losing their hair, none is as common as female pattern hair loss (FPL), a condition that affects about 40 percent of women by age fifty.
FPL is usually to blame if you notice that your hair part is starting to thin, as is the thickness you’re used to experiencing with your hair.
To help manage this condition in women, the FDA has approved only one medication — minoxidil.
As the only approved topical treatment for managing hair loss in women, minoxidil has earned an impressive reputation for helping regrow hair and control how much is lost to your bedroom floor.
But if you’re considering this hair loss medication, you’ll also want to know what to expect when it comes to its safety for use and side effects.
Despite being the only approved treatment for managing hair loss in women, minoxidil remains a bit of a mystery when it comes to its exact mechanism of action.
What we know for sure is that this medication is able to act as a potent pick-me-up during the hair growth process.
Minoxidil is able to stimulate hair growth. And to achieve this, it plays the very important role of vasodilator.
This means that it is able to promote blood flow around the hair follicles to encourage the supply of oxygen and nutrients, both of which are necessary for improving hair loss.
Minoxidil is also able to shorten the telogen — or resting phase — of hair growth, pushing hairs into a long phase where they are actively growing.
This is known as the anagen stage, and it’s at this phase that the hair growth process begins.
The outcome of this process usually leads to increased hair length and thickness for women.
When you first begin to use minoxidil in its liquid or foam formulation, you can expect to see results after around eight weeks.
By four months (on average), you’ll start seeing the maximal effects of this medication on your hair.
Check out our guide, How Long Before Minoxidil Starts Working for a better idea of when to expect results when using this product.
Minoxidil is available in foam and liquid form, and while the FDA recognizes both formulations for managing hair loss in women, its official stamp of approval is reserved only for minoxidil foam at 2% and 5%, as well as the 2% liquid solution.
If you go ahead with the minoxidil solution at 5%, it’d be considered an off-label use, and at the current time, it’s only approved for use in men — so be cautious and speak to your healthcare provider if you’re considering this option.
That said, when using the solution, it’s important to apply minoxidil directly to the scalp in the areas where you feel that improvements can be made.
This usually requires one milliliter (mL) of the solution applied twice per day to the affected area. Any more than that and you’d just be giving product away.
The same applies to using minoxidil foam. Simply massaging half a capful once a day to the affected part of the scalp should get you results following consistent usage.
To learn more about the dos and don'ts of applying topical minoxidil, see our guide, How to Apply Minoxidil for Hair Growth.
On paper, minoxidil reads like a capable treatment for managing hair loss, but how well is this medication able to get the job done?
Despite a majority of studies being carried out in men, the 2% and 5% minoxidil strengths of topical minoxidil have been found effective in treating hair loss in women.
In a study that was carried out to determine how effective a 2% minoxidil solution was against hair loss in women, hundreds of women with pattern hair loss were examined for 32 weeks while using minoxidil.
At the end of the study, 60 percent of participants reported experiencing new hair growth, with 20 percent of these reports claiming a moderate improvement in growth, and 40 percent of participants noticing a minimal increase.
Another study that pitted the 2% formulation against the 5% strength found that after 48 weeks of treatment using both strengths, women experiencing hair loss were more likely to observe faster hair growth using the 5% strength.
Those that applied 2% minoxidil also experienced hair growth, while both doses were more effective than placebos in improving hair loss in women.
The women in the study were also found to tolerate this medication quite well, with no cases of adverse effects reported.
But this is not to say that applying minoxidil doesn’t sometimes come with a helping of notable adverse reactions.
When using minoxidil to counter hair loss, an increase in hair length and density is usually what you’re looking to achieve.
But that doesn’t mean people don’t sometimes experience side effects. Luckily, minoxidil’s side effects are usually pretty mild, with its most severe reactions being likely linked to its stronger 5% dose.
Some common side effects of using this medication include:
Rashes on the skin
Excessive hair growth
Scaly appearances on the scalp
Allergic skin reactions such as eczema and itchy skin
To avoid side effects, it’s a good idea to first try out a patch test of the topical minoxidil product you intend to use. Doing this will give you a good idea of how your skin feels about applying a new foam or solution across it.
Minoxidil may also cause telogen effluvium, a form of hair loss that occurs when hairs in the telogen phase of hair growth are shed.
You’ll remember that’s one of the ways this medication encourages hair growth.
Also, minoxidil currently carries a Category C rating from the FDA, which means it’s not known whether it can cause birth defects or not.
If you’re pregnant or intend on becoming pregnant before starting or while using minoxidil, call your healthcare provider first.
You may lose your hair for any number of reasons. However, these causes of hair loss typically dictate the best methods of improving the appearance of your hair.
Depending on why you’re losing hair, you may use these methods to boost growth:
Loading up on hair improving nutrients such as iron, zinc, vitamin D, and fatty acids to promote hair strength, and to counter cases of hair loss caused by nutrient deficiencies.
Using natural products like amino acids, caffeine, onion juice, rosemary oil, saw palmetto, and others have also shown some promise as alternative or adjunctive treatments for improving hair growth.
If you are particularly distressed by the amount of hair you’ve lost, you can also consider getting a hair transplant to make up for the loss of hair.
If you’re pregnant and would like a little more information on what to do to manage your hair loss, look through our guide on Hair Loss During Pregnancy for suggestions on treatment methods that are safe for you and your child.
As things stand, minoxidil is the only FDA-approved hair loss treatment on the market for women. It’s available in both a foam and liquid treatments, at 2% and 5% concentrations.
That said, like most medications, it does come with a varying array of side effects that range from mild to wild, and include things like rashes, headaches, scaly skin and even too much or excessive hair growth.
And for women who are pregnant or intend on becoming pregnant while using minoxidil, its Category C pregnancy rating by the FDA should definitely be considered before taking it.
The point is, minoxidil is approved by the FDA because it works. However, that doesn’t mean you shouldn’t consult with your healthcare provider before you start using it — it’s always better to be safe than sorry.