Are there any drug interactions with Metformin and Vistaril (Hydroxyzine)?

No. Not really just be cautious of the drowsiness that can be a side effect of the vistaril (hydroxyzine).
Drug interactions. You can use a drug interaction checker whenever you have questions about drug-drug interactions or drug - food interactions. Here is 1 option (Drugs.Com): https://www.drugs.com/drug_interactions.php Your pharmacist is also a good source of info.