In Acrobat, go to Edit > Preferences (Windows), or Acrobat > Preferences (macOS). 
        
            
                Last updated on 
                
                    30 Sep 2022
                
            
            
        
        
    
Sanitizing a PDF increases the file size
        When you sanitize a PDF document or remove hidden information, you may notice the following changes in the document:
- The PDF is rasterized, and so you can’t edit the PDF.
- The size of the PDF document is increased.
These changes occur because Acrobat removes the overlapping content from the document by default. To prevent these changes, you need to retain the overlapping content in the PDF while sanitizing the document.