Sadluzek was formerly part of the German Empire. In the German Empire, the place was called Sadłużek.
The place is now called Sadłużek and belongs to Poland.
| Historical place name | Country | Administration | Time |
|---|---|---|---|
| Sadluzek | Russian Empire | Nešava | 1914 |
| Sadłużek | Poland | Nieszawa | 1921 |
| Sadłużek | German Empire | Hermannsbad | 1939 |
| Sadłużek | Poland | Radziejów | 1945 |
| Sadłużek | Poland | Włocławek | 1992 |