Ketoconazole shampoo is an anti-fungal, anti-inflammatory shampoo that is sometimes used to treat androgenic alopecia (AGA).
There are two formulations of ketoconazole shampoo: 1% and 2%. While 1% ketoconazole is sold over-the-counter as an ingredient in many hair loss shampoos, only 2% ketoconazole is clinically shown to improve pattern hair loss. And unfortunately, 2% ketoconazole requires a prescription from your doctor.
This leads a lot of pattern hair loss sufferers to opt for 1% ketoconazole shampoo, and mainly out of convenience. But if you’re opting for 1% ketoconazole instead of 2%, are you selling yourself short any potential hair gains?
More specifically, when it comes to 1% versus 2% ketoconazole for hair loss, does one percentage point really matter?
This Quick Win dives into the studies on ketoconazole to answer this question.
Note: Quick Wins are short articles focused on answering one question about hair loss. Given their specificity, these articles are written in a more scientific tone. If you’re new to hair loss education, start with these articles.
Is 2% ketoconazole better than 1% ketoconazole?
Currently, there are no studies directly comparing 1% to ketoconazole to 2% ketoconazole in their ability to promote hair growth.
However, we can look at some different studies that use either formulation and compare how each one performs in its respective studies. Then, we can compare the results of each study to get a feel for which one is more effective.
First, let’s look at 2% ketoconazole. This study investigated 2% ketoconazole’s ability to increase hair counts in AGA patients. They found that, after 6 months (and 3x per week of use), participants experienced an average 18% increase in hair count.
Now, let’s evaluate 1% ketoconazole. This study looked at the effectiveness of 1% ketoconazole for AGA. After 6 months of use 3x per week, 1% ketoconazole didn’t increase hair count, but it did decrease hair shedding. In other words, 1% ketoconazole is effective enough to slow or stop shedding, but not to promote hair regrowth.
Both studies employed the same frequency for the same amount of time and on subjects with the same condition. Because of this, we can assume that ketoconazole at a 2% concentration is likely more effective than at 1%.
An additional study also compared 1% versus 2% ketoconazole in their ability to combat the scalp yeast Malassezia and the condition seborrheic dermatitis. Malassezia overgrowths and seborrheic dermatitis are often observed alongside pattern hair loss. These conditions lead to excessive sebum production and scalp flaking (i.e., dandruff), and thereby may accelerate AGA by increasing overall scalp inflammation. Moreover, there’s also research suggesting that resolving Malassezia overgrowths and seborhheic dermatitis may enhance hair regrowth. Long-story short: if we’re going to use a ketoconazole formulation for hair loss, it only benefits us if that formulation also improves these conditions.
The findings from that research team? When it came to decreasing Malassezia load and scalp flakiness from seborrheic dermatitis, 2% ketoconazole outperformed 1% ketoconazole in both categories. Moreover, 2% ketoconazole led to fewer relapses of either condition.
“During follow-up [ketoconazole] 2% showed a trend to fewer relapses than [ketoconazole] 1%. [Ketoconazole] 2% had superior efficacy compared to [ketoconazole] 1% in the treatment of severe dandruff and scalp seborrhoeic dermatitis”
So, in summary: yes, there is evidence to suggest that when it comes to improving pattern hair loss, 2% ketoconazole is more effective over a six-month period versus 1% ketoconazole. The one percentage point difference does matter.
The questions then becomes: why?
Why is 2% ketoconazole better than 1% ketoconazole?
Ketoconazole is suspected to work in three ways to slow/stop hair loss and promote hair regrowth. The drug:
- Reduces inflammation related to microbial activity on the scalp.
- Reduces levels of dihydrotestosterone, the most powerful male hormone and the culprit behind AGA.
- Prolongs the anagen phase (i.e., growing phase) of the hair cycle, thereby reducing excessive shedding.
We don’t exactly know why 2% ketoconazole is better than 1% ketoconazole. But, chances are that the 2% dilution simply accomplishes these things more effectively and (maybe) more rapidly, meaning that it:
- Kills off more Malassezia, resulting in a more dramatic reduction in inflammation.
- Reduces scalp DHT more effectively and more rapidly, preventing further follicle miniaturization in AGA.
- Stimulates the transition to the anagen phase faster, thereby halting shedding and promoting hair regrowth in a shorter amount of time.
But with increasing efficacy, drugs often come with an increased risk of side effects. This is why clinical researchers often test several dilutions and doses of any drug: they’re trying to uncover which dilution or dose maximizes clinical efficacy while minimizing the risk of side effects.
So, with 1% versus 2% ketoconazole, does the increased concentration lead to an increased risk of side effects?
Does a 2% ketoconazole have a higher risk of side effects compared to 1% ketoconazole?
Although oral ketoconazole comes with significant side effects, these same side effects haven’t been reported with topical ketoconazole or ketoconazole shampoos.
This is because topical and shampoo formulations of ketoconazole are metabolized rapidly within the skin tissues, so very little (if any) topical ketoconazole actually reaches the bloodstream.
On that note, research continues to demonstrate that for the overwhelming majority of people, both 1% and 2% topical ketoconazole concentrations do not come with a notable risk of side effects.
Some individuals may experience a hypersensitivity reaction to ketoconazole topicals, however, this is relatively rare.
That being said, there is a small risk associated with the formulation of a 2% ketoconazole topical cream containing sodium sulfite. But this is a risk with the sodium sulfite, not the ketoconazole itself. And to be clear: sodium sulfite is not a standard ingredient in ketoconazole shampoo formulations (which are the ones prescribed for hair loss); it’s typically only found in topical formulations used to treat conditions like acne.
The bottom line: ketoconazole is rapidly metabolized in the skin, and therefore has minimal risks of side effects. This is why its 1% shampoo formulations are sold over-the-counter.
Should you use a 2% ketoconazole shampoo or topical?
Much like comparative studies between 1% and 2% ketoconazole, no studies have been conducted to assess whether a shampoo or a leave-on topical is more effective for hair growth.
But for now, the 2% shampoo formulation is probably the best way to go, and for two reasons:
- Topical ketoconazole hasn’t been studied for hair loss
- Topical ketocoanzole is not easy to find
In other words, 2% ketoconazole shampoo has several clinical studies demonstrating its efficacy, whereas topical ketconazole has only been evaluated in very small clinical studies (i.e., 6 participants), and typically for conditions like acne (not hair loss).
Moreover, 2% ketoconazole shampoo is readily available – all you need is a prescription from your doctor. Topical ketoconazole is typically only sold for research purposes. And while topical ketoconazole would remain on the skin for longer (and thereby potentially have a greater effect on the hair follicles), we don’t think the potential additional benefits of topical ketoconazole outweigh the risks associated with acquiring and using it.
And with 2% ketoconazole shampoo consistently demonstrating a significant benefit for AGA sufferers, it makes the most sense to opt for what we already know is safe and works.
2% ketoconazole shampoo: clinical efficacy for pattern hair loss
- This study demonstrated that a 2% ketoconazole shampoo improves hair counts in men with AGA. It also found that 2% ketoconazole is nearly twice as effective as minoxidil.
- This study compared a few singular and combination therapies: minoxidil alone, finasteride alone, minoxidil + finasteride, and 2% ketoconazole shampoo + finasteride. Although the minoxidil + finasteride combination outperformed the ketoconazole + finasteride combination, it demonstrates that 2% ketoconazole can enhance finasteride’s benefits.
- This study found that 2% ketoconazole shampoo works well in combination with finasteride in minoxidil. Participants experienced hair regrowth in as little as 30 days.
The verdict: opt for a 2% ketoconazole shampoo
The available evidence suggests that when it comes to treating pattern hair loss (AGA), a 2% ketoconazole shampoo produces better, more rapid results than a 1% ketoconazole shampoo.
Yes, you’ll need to get a prescription for 2% ketoconazole. Yes, this requires an appointment with a doctor. And yes, this is a hassle. But in all likelihood, the benefits of 2% ketoconazole outweigh the convenience of the 1% formulation.
Questions? Comments? Please reach out in the comments section.
Rob English is a researcher, medical editor, and the founder of perfecthairhealth.com. He acts as a peer reviewer for scholarly journals and has published two peer-reviewed papers on androgenic alopecia. He writes regularly about the science behind hair loss (and hair growth). Feel free to browse his long-form articles and publications throughout this site.