have just been diagnosed with shingles (Very uncomfortable!). Having to take acyclovir (antiviral) for a week does anyone know if this upsets or wipes out gut bacteria?

No its an anti-viral NOT an anti-biotic

Best people to ask would be a good pharmacist, or the original drug manufacturer/ patent holder.

If there are any gut related side effects listed in the patient information leaflet they would hopefully be able to explain why. Diarrhoea would certainly mess with the gut flora.

Pharmacist ? Yes that’s me!