Most probably, you know tretinoin as an ingredient that treats acne and signs of aging, but when it comes to hair loss, this substance represents an even more obscure field within dermatology. The interest in tretinoin in regard to hair growth appeared several decades ago, mostly due to the fact that this agent increases the bioavailability of minoxidil, one of the most researched hair loss drugs. However, does tretinoin have the power to regrow hair on its own, and what is the right way of using this product?
In this guide, we are going to look at the studies about tretinoin for hair loss, how this agent works, and how it is used.
Where the Idea Came From
Much of the research into the effects of tretinoin for hair loss dates back to a 1986 study in the Journal of the American Academy of Dermatology involving the application of topical tretinoin – either alone or combined with 0.5% minoxidil – to 56 patients who had androgenetic alopecia (or pattern hair loss):
- The use of tretinoin alone promoted some hair growth in around 58% of patients.
- The combination of tretinoin with minoxidil promoted terminal hair growth in 66% of subjects in a one-year period of treatment.
- One female patient, who had more than 20 years of significant hair loss, experienced hair growth from the use of tretinoin alone within 18 months.
- Since the initial study, most of the evidence for the use of tretinoin for hair loss has been found through combination therapy with minoxidil rather than from the use of tretinoin alone.
How Tretinoin Is Thought to Work on Hair Follicles
Tretinoin’s role in hair growth appears to work through two distinct mechanisms:
1. Enhancing Minoxidil Absorption
The most consistent finding has been the increase in percutaneous (through the skin) penetration of minoxidil by tretinoin – in the original study, tretinoin was found to cause nearly a three-fold increase in minoxidil absorption, while the effect of the vehicle solution on its own was just a 1.3-fold increase. For this reason, it makes sense to use tretinoin in combination with minoxidil because tretinoin seems to be helping with getting minoxidil where it needs to be.
2. Potential Mechanism of Action Through Effects on Hair Follicles
There is also a potential biological mechanism for how retinoic acid affects hair growth. The hair growth process involves cycles of three stages: anagen (hair growth), catagen (transitional phase), and telogen (rest). The process of pattern hair loss includes a reduction of anagen hair follicles. The hypothesis that retinoic acid may affect this process by extending the duration of the anagen stage through affecting some growth factors and activation of stem cells in the hair follicles may explain why tretinoin showed some results on its own in the original study.
However, it should be noted that the second method is not as well-established as the previous one, and there is still much less research on tretinoin in relation to hair loss compared to the amount of studies done regarding minoxidil or finasteride.
Does Tretinoin Work for Hair Loss on Its Own?
From what is known in the scientific literature, tretinoin monotherapy could yield a significant albeit moderate effect in some patients, as seen by the partial response rate of 58% recorded in the initial study, and while not particularly impressive, it is far from being inconsequential. On the other hand, tretinoin monotherapy for hair loss has received significantly less research than minoxidil and finasteride, both of which boast a vast body of literature regarding hair loss treatment.
However, in patients who are unable to use topical minoxidil because of their scalp sensitivity, hair growth on their face, or systemic absorption issues, the use of tretinoin monotherapy should be considered a good option to discuss with their dermatologist, especially in the earlier stages of thinning. But in the majority of cases, the superior case for tretinoin usage lies in its combinations with other therapies.
How Tretinoin Is Typically Combined With Minoxidil
Since many of the relevant studies focus on the combination therapy, here is how the combination approach is usually used in practice:
- Compounded preparations: There are some doctors who provide patients with compounded solutions, which contain a small amount of tretinoin (about 0.01–0.025%) together with minoxidil, and which are supposed to be used simultaneously.
- Seperate application: Another way to use tretinoin and minoxidil in combination is to apply these medications in a separate way – tretinoin at night and minoxidil during the day, to avoid irritating reactions resulting from the simultaneous application of these strong compounds, unless a preparation that allows for simultaneous application is used.
- Minoxidil in smaller concentrations might act in the same way: In the course of the original study, it was discovered that even minoxidil in smaller concentrations (0.5%), together with tretinoin, works effectively, significantly less than those that are 2–5%, usually prescribed separately.
How to Use Tretinoin for Hair Loss Safely
If you and your healthcare provider agree that tretinoin is worth trying for hair loss, the right technique is key – the scalp, much like facial skin, can react quite strongly to tretinoin, with irritation being the top reason why people stop using it too early.
1. Start With a Low Concentration
Most regimens involve starting at about 0.025%, which is not only the strength that has been most studied for hair but also the one easiest on the scalp.
2. Apply a Thin Layer to Affected Areas Only
Instead of applying tretinoin to the entire scalp, apply it in small amounts to the areas where hair is thinning, once daily – typically at bedtime in conjunction with minoxidil in the mornings.
3. Watch for Signs of Irritation
Dryness, redness, burning sensation, or flaking of the scalp may indicate that the dose or frequency should be modified. In other cases, overuse was reported to result in increased shedding, which could erroneously be interpreted as the ineffectiveness of the therapy, but only a normal response of irritated skin.
4. Give It Time
The effect of tretinoin on the skin is a gradual process, and the same applies to its impact on hair growth. Significant improvements in terms of increased density and thickness, based on the research available, take place within several months of regular application.
5. Don’t Combine Without Guidance
In case you are interested in using a combination of tretinoin with minoxidil, finasteride, or dutasteride preparations, it must be prescribed by an experienced practitioner due to the risk of irritation and the need for proper concentration.
Who Might Be a Reasonable Candidate
- Those individuals taking minoxidil but failed to produce their desired results, and are wondering if combining them will make things better
- Individuals suffering from androgenic hair loss at an initial stage and looking for other treatment options in addition to existing ones
- Individuals who cannot take regular topical minoxidil due to its negative effects on them
Who Should Be Cautious or Avoid It
- Pregnant or lactating women, just as with face application, tretinoin has safety concerns related to pregnancy that also apply to scalp application.
- Individuals suffering from scalp disorders such as eczema, psoriasis, and other existing skin irritations should avoid tretinoin, as it can exacerbate them.
- Individuals looking for a fast solution or an immediate effect – the evidence that exists indicates a slow improvement at best.
- Individuals compounding tretinoin on their own – doing so is likely to cause more skin irritation without providing more benefits.
Setting Realistic Expectations
It’s important to address the state of current evidence directly – hair loss tretinoin is an intriguing and decades-long area of study, but one that has received far less attention than minoxidil or finasteride independently, and even less when it comes to the most compelling evidence, which deals with combination treatment. While the 1986 study was certainly groundbreaking in its time, the fact is that it featured a relatively small number of patients (only 56).
Additionally, there have been no large-scale studies on hair loss tretinoin since then.
This does not mean that it should be ignored completely – especially when it comes to being used alongside minoxidil – but it does mean that tretinoin cannot be considered a scientifically proven cure for hair loss in the same sense that it is for acne and photoaging.
How Tretinoin Compares to Established Hair Loss Treatments
To understand how tretinoin fits into the bigger picture, it would be useful to compare tretinoin with the most proven options for pattern hair loss:
- Minoxidil: A drug approved by the FDA for treating hair loss, with a substantial and proven body of scientific literature demonstrating cosmetically noticeable hair growth in approximately 30-40% of patients at regular concentrations (2-5%) when used on its own. Minoxidil remains the more proven and first-line drug, with tretinoin being used mainly as a supplementary medication.
- Finasteride/Dutasteride: A group of drugs that act by targeting the underlying causes of pattern hair loss (hormones) and have been extensively researched and studied. Tretinoin does not target these pathways and cannot be regarded as a replacement for these two drugs.
- Tretinoin: Mainly recommended for use in combination, as an additive enhancing the efficacy of minoxidil. Also has a moderate amount of evidence supporting the use of this drug on its own, but not approved by the FDA for hair loss. Off-label use of the drug, mainly prescribed by dermatologists aware of compounded formulations.
For most people considering hair loss treatment, tretinoin should be regarded as an addition to their current routine.
Final Thoughts
The use of tretinoin in hair loss is quite an intriguing yet less studied aspect of dermatology – one that is indeed based on decades of clinical experience but not quite as extensively proven as the use of this treatment for acne and photoaging. The only clear conclusion to be drawn from the existing data is that tretinoin should be used as an adjunct to minoxidil, which helps improve absorption of the latter and increase the effectiveness of the treatment overall.
If you are considering using tretinoin for your hair loss problem, the way to proceed would be a consultation with a dermatologist or hair restoration specialist to establish the type of your hair loss and whether tretinoin will be beneficial to your case.
Frequently Asked Questions
Does tretinoin regrow hair on its own?
While some sources have suggested that tretinoin can cause a modest response rate, at about 58%, partial response, in the original foundational study, the scientific basis for its effects on hair growth is relatively small compared to other proven methods, such as minoxidil and finasteride.
Why is tretinoin combined with minoxidil for hair loss?
It seems that tretinoin dramatically improves the skin absorption of minoxidil, which is supposed to enhance the effect of the latter rather than be used as a stand-alone remedy.
What concentration of tretinoin is used for hair loss?
The vast majority of protocols rely on lower concentrations, ranging between 0.01% and 0.025%, which are applied to the scalp as a thin coat, usually lower compared to what is normally used when treating skin concerns of the face.
How long does it take to see results?
Based on available studies, meaningful improvement in hair regrowth and density generally develops over several months to about a year of consistent use, similar to the timeline for other topical hair loss treatments.
Is tretinoin for hair loss FDA-approved?
Not yet. While FDA-approved for acne and photodamage, tretinoin is not approved for hair loss, and its use for this purpose remains off-label.
