Cold sore Q&A

What is HSV-1 and how does it trigger cold sores?

HSV-1 (herpes simplex virus type 1) is a neurotropic virus dormant in the trigeminal ganglion, reactivating when UV exposure, immune stress, or irritation lowers your defences. The virus travels to the lip surface, triggering the blister cascade of herpes labialis. Most lip balms accelerate this: menthol and camphor thin the skin barrier and increase UV penetration. Labisan's 22% zinc oxide delivers SPF 20 mineral protection that physically blocks the primary UV trigger, while manuka oil and graviola annonacin reinforce local immunity without chemical irritants.

Evidence

  • UV radiation is the most documented HSV-1 reactivation trigger, with sunlight exposure linked to measurably higher outbreak frequency in controlled clinical observations.
  • Zinc oxide at 22% concentration provides broad-spectrum UV attenuation and antiviral surface activity against enveloped viruses including herpesviruses.
  • Menthol and camphor, present in most lip balms, act as keratolytics at repeated application and compromise stratum corneum barrier function, increasing reactivation risk.

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