Tretinoin and Minoxidil: Can Tretinoin Improve Hair Growth Results?

Minoxidil is one of the most established topical treatments for androgenetic alopecia (pattern hair loss). But for some people, minoxidil alone may not produce the desired response.

One treatment that has attracted interest as a potential addition to minoxidil is tretinoin.

Tretinoin is a prescription retinoid that has been used in dermatology for many years. Research suggests that, when used alongside minoxidil, tretinoin may help improve the way some hair follicles respond to minoxidil.

How does minoxidil work?

Minoxidil works directly on the hair follicle and can help prolong the anagen, or active growth, phase of the hair cycle.

It can help miniaturised follicles produce thicker hairs and is commonly used as a first-line topical treatment for androgenetic alopecia.

However, not everyone responds to minoxidil in the same way.

One possible reason is that minoxidil needs to be converted into its active form, minoxidil sulfate, within the hair follicle.

The enzyme responsible for this conversion is called sulfotransferase, and the activity of this enzyme varies between individuals.

How could tretinoin help?

Research has investigated whether tretinoin can increase follicular sulfotransferase activity.

A 2019 study found that topical tretinoin increased sulfotransferase activity in the hair follicle. Interestingly, some people who were initially predicted to be poor responders to minoxidil were subsequently classified as responders following tretinoin treatment.

This provides a possible explanation for why adding tretinoin may help certain individuals who have not achieved an adequate response to minoxidil alone.

Tretinoin may also influence the penetration of topical treatments through the skin, potentially increasing the amount of minoxidil reaching the hair follicle.

What does the clinical research show?

There is some clinical evidence supporting the combination.

One study compared 5% minoxidil used twice daily with a combination of 5% minoxidil and 0.01% tretinoin used once daily in men with androgenetic alopecia.

The combination treatment produced improvements comparable to twice-daily 5% minoxidil, suggesting that tretinoin may have a useful role as an adjunct to topical minoxidil.

However, it is important not to overstate these findings.

The evidence base for tretinoin and minoxidil remains considerably smaller than the evidence supporting minoxidil itself. Tretinoin should therefore be considered a potential adjunct, rather than something that will necessarily improve results for every person.

Who might benefit from tretinoin with minoxidil?

A combination approach may be worth discussing with a prescriber if you:

• Have androgenetic alopecia
  
• Are already using topical minoxidil but have had a limited response
  
• Want to optimise a topical treatment regimen
  
• Prefer a personalised topical approach
  
• Have experienced a plateau with your current treatment

Treatment should always be individualised. Simply adding more active ingredients or using higher concentrations does not necessarily produce better results.

What concentration of tretinoin is used?

Studies investigating the combination have included 0.01% tretinoin alongside topical minoxidil.

Using a lower concentration can be particularly relevant when tretinoin is being used as an adjunct to another active treatment, because tretinoin can cause irritation, dryness, redness and peeling.

Higher concentrations are not automatically more effective for hair growth and may increase the likelihood of scalp irritation.

What are the potential side effects?

Tretinoin can cause:

• Dryness
  
• Redness
  
• Peeling
  
• Itching
  
• Burning or irritation

Minoxidil can also cause scalp irritation in some people, particularly depending on the formulation and vehicle used.

Combining the two therefore isn't suitable for everyone. If significant or persistent irritation develops, treatment should be reviewed by an appropriate healthcare professional.

Tretinoin isn't a replacement for minoxidil

It is important to understand that tretinoin and minoxidil work differently.

Minoxidil is the primary hair-growth treatment, while tretinoin is being investigated as a potential adjunct that may improve the follicle's response to minoxidil.

For someone considering treatment for pattern hair loss, the overall strategy should take into account the underlying cause of hair loss, the severity and pattern of thinning, previous treatments and individual risk factors.

Exploring personalised minoxidil treatment

If you are interested in topical minoxidil and want to learn more about personalised formulations, you can read more about the options available through our associated specialist hair-loss prescribing service:

Explore personalised minoxidil treatment at HairRx Clinic

The bottom line

There is a scientific rationale and some clinical evidence for combining tretinoin with minoxidil.

Tretinoin may increase follicular sulfotransferase activity and could potentially improve the response to topical minoxidil in some individuals. However, the available evidence is still limited, so it would be inaccurate to say that tretinoin will boost minoxidil results for everyone.

For selected patients, however, tretinoin 0.01% may be a useful adjunct to a personalised topical minoxidil treatment plan.

As with any prescription treatment, suitability should be assessed on an individual basis.