When medications such as Prozac, Wellbutrin, or Lamisil are taken with Toprol-XL, interactions between the drugs may occur. Some drug interactions with Toprol-XL may cause your body to metabolize the medicines differently than intended or lead to side effects such as extremely high blood pressure, slowed heart rate, or high blood sugar levels. Other medicines that may cause Toprol-XL interactions include nonsteroidal anti-inflammatory drugs (NSAIDs), monoamine oxidase inhibitors (MAOIs), cimetidine, and terbinafine.