I just came back from a trip in Italy, didn't need a International driver license.
BTW I almost didn't see cops pulling people. I drove all over northern Italy. My partner speed away and no ticket at all.
So I wouldn't worry. But I personally would obey all rules anyway.
ITALIAN MOTOR VEHICLE CODE - Art 135
Art . 135. Circulation with driver’s licenses issued by foreign states .
1. Notwithstanding the provisions of the international conventions, the holders of a driver’s license issued by a non -EU Member State or the European Economic Area may drive the vehicles for which they are licensed in the Italian national territory, provided that they are not residents in Italy for more than a year and provided that they also carry an
international permit or an official translation into Italian of their home country license. Driver's license and international permit must be current and valid.[…]
8. The holder of a driver’s license issued by a State outside the European Union or the European Economic Area that drives a vehicle within the Italian national territory
without the international permit or an official translation, as referred to in paragraph 1, is subject to an administrative
fine ranging from
400 Euro to 1,600 Euro.