diff --git a/Doc/library/textwrap.rst b/Doc/library/textwrap.rst
index a58b460fef409c..ca9f55caa63a9a 100644
--- a/Doc/library/textwrap.rst
+++ b/Doc/library/textwrap.rst
@@ -102,6 +102,10 @@ functions should be good enough; otherwise, you should use an instance of
           print(repr(s))          # prints '    hello\n      world\n    '
           print(repr(dedent(s)))  # prints 'hello\n  world\n'
 
+   .. versionchanged:: next
+      The :func:`!dedent` function now correctly normalizes blank lines containing
+      only whitespace characters. Previously, the implementation only normalised
+      blank lines containing tabs and spaces.
 
 .. function:: indent(text, prefix, predicate=None)
 
diff --git a/Doc/whatsnew/3.14.rst b/Doc/whatsnew/3.14.rst
index ac5b53ef94bfb1..7bd02d739fc924 100644
--- a/Doc/whatsnew/3.14.rst
+++ b/Doc/whatsnew/3.14.rst
@@ -1072,6 +1072,14 @@ io
   :gh:`120754` and :gh:`90102`.)
 
 
+textwrap
+--------
+
+* Optimise the :func:`~textwrap.dedent` function, improving performance by
+  an average of 2.4x, with larger improvements for bigger inputs,
+  and fix a bug with incomplete normalization of blank lines with whitespace
+  characters other than space and tab.
+
 uuid
 ----