Is petroleum jelly safe for vaginal itdhing?

Yes: It would be safe but it may not be effective.

Doesn't treat: Pertroleum jelly, as the name suggest is a petroleum product that can degrade condoms or a diaphragm. It doesn't treat the cause of itching, which might be a yeast infection that should be treated with an antifungal medication or other skin condition. It's not necessarily harmful, but may not be helpful.