A popular skincare trend on social media might actually have some scientific truth behind it.
A new study from the Perelman School of Medicine at the University of Pennsylvania found that a compound in rosemary leaves could help skin wounds heal better and leave less scarring.
The study, published in JCI Insight, shows that an antioxidant found in rosemary—called carnosic acid—may shift the healing process away from scarring and toward more natural skin regeneration.
Many people who suffer from cuts or other skin injuries end up with scars, which can be more than just cosmetic issues. In some cases, scars can lead to long-term problems. That’s why researchers are excited about the possibility of a cream that could promote healing without leaving scars.
Interestingly, this research started when two students from Penn—undergraduate Jiayi Pang and Ph.D. student Emmanuel Rapp Reyes—noticed that beauty influencers on TikTok and Instagram were using rosemary in their skincare routines.
They wondered if there was any truth to the hype and brought the question to Dr. Thomas Leung, a dermatology professor at Penn. Together, they decided to test rosemary in the lab.
Rosemary contains several antioxidants, which help protect cells from damage. The team believed that one of these, carnosic acid, might have real healing powers.
So, they created a special cream using carnosic acid and tested it on mice. The cream not only helped wounds close faster, but it also helped restore hair follicles, oil glands, and even cartilage—things that usually don’t grow back after an injury.
The researchers discovered that this healing process depended on a nerve sensor in the skin called TRPA1. In past research, this sensor was shown to be essential for scar-free healing. When they tested the cream on mice that didn’t have this TRPA1 sensor, the healing effects disappeared. This confirmed that carnosic acid works through this specific pathway.
The team also tested other herbs, like thyme and oregano, that might activate TRPA1. While those herbs showed some promise, rosemary worked best and was the safest. Some other substances that stimulate TRPA1, like mustard oil or the medication imiquimod, can cause redness or irritation—problems not seen with rosemary.
Another interesting finding was that the rosemary cream only worked when applied directly to the wound. It didn’t help if it was applied to skin far away from the injury, meaning the effect is very localized.
Although these results are promising, the researchers warn that people shouldn’t rush to mix up their own rosemary creams at home. It’s always best to talk to a doctor before adding new products to your skincare routine.
Still, since rosemary is affordable and easy to find, this study could lead to new wound care treatments, especially for people who are at higher risk of scarring.
“If you’re using rosemary in your skincare and it seems to help, it probably is,” said Dr. Leung. “What’s exciting is that this discovery came from students asking real-life questions based on what they were seeing around them.”
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The study is published in JCI Insight.
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