There are some potential risks and side effects associated with using Nexium or other proton pump inhibitors (PPIs) for infants with reflux. Studies have shown an increased risk of allergies, including food allergies, medication allergies, seasonal allergies, and asthma in the future. Additionally, there may be a higher risk of fractures in infants due to reduced calcium absorption when using these medications. It is important to use these medications for a short period and regularly reassess the need for them. If you have any concerns or questions, it is best to consult with a healthcare provider.