diff --git a/src/pip/_internal/commands/install.py b/src/pip/_internal/commands/install.py
index 1279d4a..aeb9d26 100644
--- a/src/pip/_internal/commands/install.py
+++ b/src/pip/_internal/commands/install.py
@@ -5,6 +5,8 @@ import logging
 import operator
 import os
 import shutil
+import sys
+from os import path
 from optparse import SUPPRESS_HELP
 
 from pip._vendor import pkg_resources
@@ -217,6 +219,23 @@ class InstallCommand(RequirementCommand):
 
     def run(self, options, args):
         cmdoptions.check_install_build_global(options)
+
+        def is_venv():
+            return (hasattr(sys, 'real_prefix') or
+                    (hasattr(sys, 'base_prefix') and
+                     sys.base_prefix != sys.prefix))
+
+        # Check whether we have root privileges and aren't in venv/virtualenv
+        if os.getuid() == 0 and not is_venv():
+            command = path.basename(sys.argv[0])
+            if command == "__main__.py":
+                command = path.basename(sys.executable) + " -m pip"
+            logger.warning(
+                "Running pip install with root privileges is "
+                "generally not a good idea. Try `%s install --user` instead."
+                % command
+            )
+
         upgrade_strategy = "to-satisfy-only"
         if options.upgrade:
             upgrade_strategy = options.upgrade_strategy