Tretinoin is a treatment derived from Vitamin A and belongs to a group of medications called retinoids. You'll usually hear about it as a skincare treatment - it's often prescribed as a cream or tablet to treat acne or sun damage. But interestingly, research suggests that tretinoin may also help minoxidil absorb more effectively into the scalp, which could make minoxidil work better overall.
What does the research say?
- One group used 5% Minoxidil Spray twice a day.
- The other group used a once-daily combination of 5% minoxidil and 0.01% tretinoin.
The results didn't show significant differences in hair count, growth rate, or other measures. In simpler terms, adding a small amount of tretinoin seemed to help minoxidil absorb well enough that it only needed to be applied once a day, which could be great news for anyone who struggle with the twice-daily routine. Better consistency usually means better long-term results.
Another proposed reason tretinoin might boost minoxidil's effectiveness is its potential role in converting minoxidil into its active form, minoxidil sulphate. For this conversion to happen, sulfotransferase enzymes on the hair follicles are needed, and people naturally have different levels of them. Some researchers believe that measuring these enzymes could help predict whether a person will respond to Minoxidil.
In one small study, researchers tested this idea by measuring sulfotransferase activity in twenty people, then having them apply 0.1% tretinoin cream for five days. Enzyme activity increased significantly, and 43% of those predicted not to respond to minoxidil became likely responders. This research suggests tretinoin might upregulate sulfotransferase on the scalp and make Minoxidil Spray work for somebody that previously may not have responded.
Another study explored a combination treatment of minoxidil 5%, a steroid, and a retinoid in 66 Black women with various hair loss conditions. Minoxidil sprays usually contain alcohols to help with absorption, but these can cause irritation or dryness. The study found that 84.7% of participants using the combination treatment continued for six months, compared with only 44.7% using minoxidil alone. This suggests that gentler alternatives to alcohol-based formulas may improve comfort, consistency, and over treatment success.
Other ways to boost Minoxidil absorption
While these studies are promising, Minoxidil-Tretinoin combination sprays aren't widely available and usually require a prescription. Minoxidil 5% Spray, however, is readily available over the counter.
If you're struggling to remember to apply Minoxidil Spray twice a day, or your scalp is sensitive and you've experienced irritation and/or dryness, Oral Minoxidil could be a suitable alternative. It is a capsule version of minoxidil which can be prescribed off-label to stop hair loss, and studies suggest it could work as well as the spray. As it is a capsule, it only needs to be taken once-a-day, which many find easier to keep up with than Minoxidil Spray.
Another simple way to potentially improve Minoxidil absorption is by using a derma roller. This small handheld device has tiny needles that create micro-injuries on the scalp when rolled gently over the skin. It is thought to create tiny micro-channels to help Minoxidil penetrate the skin barrier more easily so it can reach the hair follicles, and studies have show that results are improved when using a derma roller with Minoxidil Spray. You can read more about how to use a derma roller and its benefits for hair growth here.
The best way to get the most out of Minoxidil Spray is to use it consistently. If you need help building a routine that sticks - something that feels as natural as brushing your teeth - check out our helpful guide with tops backed by psychological research to help you create lasting habits.
All of our blog articles are reviewed by our Medical Director before publication.
