Most people know herpes as a cold sore that flares up and fades again. For many it is easy enough to live with. For a smaller group of patients, the usual pills simply stop working.
On October 9, 2026, the US Food and Drug Administration approved a new oral drug called Hovilpri. Its active ingredient is pritelivir.
According to Contemporary OB/GYN, the pill is cleared for adults with weakened immune systems. Their herpes sores must have failed to respond to the standard antivirals acyclovir, valacyclovir, or famciclovir.
Why the standard pills stop working
What makes pritelivir different is how it goes after the virus. The older herpes pills need the virus to switch them on using one of its own enzymes, called thymidine kinase.
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When the virus mutates away from that enzyme, those pills quietly lose their effect. Pritelivir blocks a completely different step in viral copying, called the helicase-primase complex.
It is the first herpes drug with a genuinely new way of working to be approved in nearly 30 years.
Who is most affected
The approval matters most for a small but vulnerable group of patients. Organ transplant recipients, people living with HIV, patients with blood cancers or stem cell transplants, and others on strong immune-suppressing drugs are the main targets.
In these patients, a herpes outbreak can spread, cause real pain, and refuse to heal. When the usual pills stop working, there has been very little else to offer.
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What the clinical trial showed
The approval was based on a late-stage study of 101 adults with weakened immunity whose herpes sores had resisted standard treatment.
By day 28, about 63% of patients on pritelivir had sores that fully healed. In the group given the usual alternative treatments, only 34% had healed.
When treatment was allowed to run up to day 42, healing rose to roughly 82% on pritelivir, against 42% in the comparator group. Headache was the most common side effect.
Dr. Genovefa Papanicolaou, clinical director of the infectious disease service at Memorial Sloan Kettering Cancer Center, has described the challenge for these patients. Contagion Live carried her statement.
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"In patients with blood cancers or those who have undergone stem cell transplantation, refractory HSV infections can be prolonged, painful, and difficult to treat," she said.
When patients can get it
Hovilpri is a once-daily tablet from Asahi Kasei Therapeutics. Dosing begins with a 400 mg loading dose on day one, followed by 100 mg once a day.
Patients whose herpes sores are not healing on standard pills should ask their specialist whether they qualify. The manufacturer has said it expects the drug to be available in the United States before the end of 2026.
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This article is made and published by Aksel Kryhlmand, who may have used AI in the preparation.