I have my own mouthwash at home. Can I use that instead of the one I was prescribed?

After surgery you should use the mouthwash we prescribed (chlorhexidine, such as Hexamedine) first. The prescribed rinse has strong antibacterial action and is meant to prevent infection at the surgical site, while over-the-counter mouthwash is mainly for breath and a fresh feeling and plays only a supporting role - they serve different purposes. The prescribed rinse is used for a short period, usually one week; using it for longer can cause tooth staining or changes in taste. Once the prescribed period is over, you may go back to your usual mouthwash.