My Rheumatologist has prescribed Hydroxychloroquine. It is causing stomach upset. Will taking the brand name Plaquenil result in less stomach upset?

Hydroxychloroquine and Plaquenil are one and the same drug, so you are likely to have the same reaction with Plaquenil. In some cases stopping the drug for a few days and then re-starting more gradually may stop the gastric upset. However, I would advise you to discuss this with your GP, and if you continue to have gastric problems I would advise you to inform your rheumatologist.