diff --git a/doc/api/next_api_changes/2019-01-13-AL.rst b/doc/api/next_api_changes/2019-01-13-AL.rst
new file mode 100644
index 000000000000..1038852ae000
--- /dev/null
+++ b/doc/api/next_api_changes/2019-01-13-AL.rst
@@ -0,0 +1,4 @@
+Deprecations
+````````````
+
+``Text.is_math_text`` is deprecated.
diff --git a/lib/matplotlib/contour.py b/lib/matplotlib/contour.py
index 59b9fe63babb..70a6deb012aa 100644
--- a/lib/matplotlib/contour.py
+++ b/lib/matplotlib/contour.py
@@ -264,7 +264,7 @@ def get_label_width(self, lev, fmt, fsize):
         if not isinstance(lev, str):
             lev = self.get_text(lev, fmt)
 
-        lev, ismath = text.Text.is_math_text(lev)
+        lev, ismath = text.Text()._preprocess_math(lev)
         if ismath == 'TeX':
             if not hasattr(self, '_TeX_manager'):
                 self._TeX_manager = texmanager.TexManager()
diff --git a/lib/matplotlib/text.py b/lib/matplotlib/text.py
index d264ad38cdd4..ca997485ff3d 100644
--- a/lib/matplotlib/text.py
+++ b/lib/matplotlib/text.py
@@ -286,11 +286,12 @@ def _get_layout(self, renderer):
 
         # Full vertical extent of font, including ascenders and descenders:
         _, lp_h, lp_d = renderer.get_text_width_height_descent(
-            "lp", self._fontproperties, ismath=False)
+            "lp", self._fontproperties,
+            ismath="TeX" if self.get_usetex() else False)
         min_dy = (lp_h - lp_d) * self._linespacing
 
         for i, line in enumerate(lines):
-            clean_line, ismath = self.is_math_text(line, self.get_usetex())
+            clean_line, ismath = self._preprocess_math(line)
             if clean_line:
                 w, h, d = renderer.get_text_width_height_descent(
                     clean_line, self._fontproperties, ismath=ismath)
@@ -697,8 +698,7 @@ def draw(self, renderer):
                 y = y + posy
                 if renderer.flipy():
                     y = canvash - y
-                clean_line, ismath = textobj.is_math_text(line,
-                                                          self.get_usetex())
+                clean_line, ismath = textobj._preprocess_math(line)
 
                 if textobj.get_path_effects():
                     from matplotlib.patheffects import PathEffectRenderer
@@ -1152,6 +1152,7 @@ def set_text(self, s):
             self.stale = True
 
     @staticmethod
+    @cbook.deprecated("3.1")
     def is_math_text(s, usetex=None):
         """
         Returns a cleaned string and a boolean flag.
@@ -1174,6 +1175,27 @@ def is_math_text(s, usetex=None):
         else:
             return s.replace(r'\$', '$'), False
 
+    def _preprocess_math(self, s):
+        """
+        Return the string *s* after mathtext preprocessing, and the kind of
+        mathtext support needed.
+
+        - If *self* is configured to use TeX, return *s* unchanged except that
+          a single space gets escaped, and the flag "TeX".
+        - Otherwise, if *s* is mathtext (has an even number of unescaped dollar
+          signs), return *s* and the flag True.
+        - Otherwise, return *s* with dollar signs unescaped, and the flag
+          False.
+        """
+        if self.get_usetex():
+            if s == " ":
+                s = r"\ "
+            return s, "TeX"
+        elif cbook.is_math_text(s):
+            return s, True
+        else:
+            return s.replace(r"\$", "$"), False
+
     def set_fontproperties(self, fp):
         """
         Set the font properties that control the text.