Researchers at the University of Pennsylvania have reported that a compound in rosemary can speed wound healing and reduce scarring in mice. The work, published in JCI Insight, identifies carnosic acid as a key driver of this effect through activation of a regenerative skin nerve sensor, suggesting a potential low-cost avenue for future human wound-care research.
A viral skincare trend on platforms such as TikTok and Instagram has popularized rosemary serums and other rosemary-based products for skin recovery, prompting curiosity among scientists.
According to a news release from the University of Pennsylvania’s Perelman School of Medicine, undergraduate student Jiayi Pang and PhD candidate Emmanuel Rapp Reyes noticed the online claims and approached dermatologist Thomas Leung, an associate professor at Penn, to investigate whether there was a scientific basis for them.
Their findings, reported in the journal JCI Insight, describe experiments in which the research team worked with mice and tested a cream made with carnosic acid, a naturally occurring antioxidant found primarily in rosemary leaves.
In adult mouse wound-healing models, the cream accelerated wound closure and was associated with the regeneration of skin structures, including hair follicles, oil glands and cartilage, changes that together pointed to reduced scarring rather than typical fibrotic repair.
Mechanistic studies showed that the treatment activated a skin nerve sensor known as TRPA1, a nociceptor on cutaneous sensory neurons that previous work had tied to the capacity for scarless or regenerative healing. When the carnosic-acid cream was applied to mice that lacked TRPA1 in sensory neurons, the pro-regenerative effect was lost, confirming that this pathway was essential for the observed response.
The Penn team also found that rosemary’s impact was localized: scar-sparing, regenerative healing occurred only at wound sites where the carnosic-acid cream was applied. Treating distant, uninjured skin did not produce the same benefit, indicating that the effect depends on direct application to the injured area.
In screening other botanicals and compounds, the researchers identified additional TRPA1-activating herbs, including thyme and oregano. However, rosemary stood out for its combination of potency and apparent safety in their mouse experiments. Other natural ingredients and medications known to stimulate TRPA1, such as mustard oil or the topical immune-response modifier imiquimod, can cause irritation and inflammation, making them less attractive as wound-care candidates.
“Many skin injuries end in scars, and in some people, it can lead to long-term cosmetic and even functional issues,” Leung said in the Penn release, quoted by ScienceDaily. “Our findings suggest that rosemary extract, and specifically the antioxidant, carnosic acid, can shift the healing process from scarring to healthy skin regeneration. We don’t have proven ways to consistently do that in humans.”
Pang, a co-lead author, added that the team suspected there was a real biological signal behind the online hype: “We hypothesized there was likely something real behind the hype because rosemary contains many antioxidants,” she said. “But we knew in order to really uncover its potential, we needed to prove its healing properties and uncover how exactly it was facilitating healing.”
Rapp Reyes, the study’s other co-lead author, said rosemary distinguished itself during testing. “We also identified other herbs, such as thyme and oregano, that may activate TRPA1. But rosemary stood out for its potency and safety,” he noted.
Despite the encouraging mouse data, the researchers emphasized that the results are preliminary and do not establish effectiveness or safety of over-the-counter or homemade rosemary products in people. The Penn team advises individuals to consult their healthcare providers before adding rosemary-based products to their skincare regimens or preparing their own mixtures.
Because rosemary is widely available and relatively inexpensive, the scientists hope their work will motivate further research into its potential role in human wound care, particularly for patients who are prone to pronounced scarring.
“If rosemary is part of your skincare regimen and you think it’s working, it likely is,” Leung said, adding that he was proud that young scientists led a study rooted in questions that arose from everyday life.
The study, “Carnosic acid in topical rosemary extract enhances skin repair via TRPA1 activation,” was published in JCI Insight in October 2025.
