diff --git a/conan/api/output.py b/conan/api/output.py
index 0e856477e8b..34d10ac94d9 100644
--- a/conan/api/output.py
+++ b/conan/api/output.py
@@ -156,6 +156,7 @@ def _write_message(self, msg, fg=None, bg=None):
             ret += "{}".format(msg)
 
         self.stream.write("{}\n".format(ret))
+        self.stream.flush()
 
     def trace(self, msg):
         if self._conan_output_level <= LEVEL_TRACE: