What additional condition warrants the use of antiviral treatment for shingles, regardless of the timing?

The use of antiviral treatment for shingles (herpes zoster) is indicated primarily to reduce the severity and duration of the symptoms, particularly when there are complications or specific circumstances. Among those circumstances, non-truncal involvement serves as a critical factor justifying antiviral treatment regardless of the timing since it can indicate a more severe infection.

When shingles affects areas outside of the trunk, especially involving the face or the eyes, there is a higher risk of complications such as postherpetic neuralgia and ocular involvement which can lead to vision loss. Immediate treatment in these cases is vital to prevent further complications.

The other conditions listed do not universally warrant antiviral treatment. Age over 100 years may increase the risk of complications but does not solely justify immediate antiviral therapy without considering the overall clinical picture. Severe pain alone, while distressing, does not necessarily point to the need for antiviral intervention, as antiviral therapy is more about preventing complications rather than solely alleviating pain. Similarly, the presence of nausea does not correlate directly with the necessity for antiviral medications, as it is not a typical indicator of shingles severity itself.