A common human cold sore cream may soon help cats with painful eye infections: researchers found that 1% penciclovir cream (Fenlips®), when applied to cats’ eyes, was safe, well-tolerated, and maintained antiviral levels for over eight hours—suggesting that twice-daily use could effectively manage feline herpesvirus type 1, a leading cause of eye disease in cats.

A cream originally developed for human cold sores may soon become a game-changer for cats battling eye infections. Researchers from the have found that a 1% penciclovir cream (sold under the brand name Fenlips®) is safe, well-tolerated, and effective when used to treat eye infections caused by feline herpesvirus type 1 (FHV-1).

FHV-1 is one of the most common causes of eye disease in cats, often leading to chronic infections, discomfort, and vision problems. Standard antiviral treatments, such as oral famciclovir, can be difficult for owners to administer and have limited absorption in cats.

A new study led by Dr. Oren Pe’er, together with Dr. Lionel Sebbag and Prof. Ron Ofri from the Ophthalmology Department at the Koret School of Veterinary Medicine, Hebrew University, in collaboration with Prof. Sara Thomasy and her team at the School of Veterinary Medicine at the University of California, Davis, demonstrates that a topical cream commonly used in human dermatology may be safely repurposed for treating feline herpesvirus (FHV-1) eye infections.

The findings highlight an innovative, practical treatment approach that could simplify therapy for cat owners and improve outcomes in one of the most common feline eye diseases.

“Our findings suggest that a simple over-the-counter cream could offer an easier, effective option for cat owners struggling to manage recurrent eye infections,” said Dr Pe’er
In a retrospective survey, most cat owners reported excellent tolerance and visible improvement when using Fenlips®, with 85% noting no side effects and 80% rating the treatment as effective or highly effective. To confirm safety and effectiveness, the researchers conducted additional studies in healthy cats over a month-long period. No adverse reactions were observed, and tear tests showed that penciclovir levels stayed above the concentration needed to inhibit the herpesvirus for over eight hours after application.

“This means twice-daily application could be enough to keep the virus in check,” “It’s a major step toward improving both animal welfare and treatment compliance.”

The findings, published in Veterinary Science, provide early evidence that Fenlips® may be a promising new option for veterinarians treating FHV-1-related eye disease. The researchers emphasize that while the results are encouraging, further studies in larger patient populations are needed before the treatment can be formally approved for ophthalmic use in cats.
The findings, published in Veterinary Science, add to previous study by the team demonstrating the efficacy of Fenlips® in reducing clinical signs associated with feline herpesvirus infection, and provide early evidence that Fenlips® may be a promising new option for veterinarians treating FHV-1–related eye disease. The researchers emphasize that while the results are encouraging, further studies in larger patient populations are needed before the treatment can be formally approved for ophthalmic use in cats.