Upgrading pip safe?

During the installation of version 0.28 I got this message:

The directory '/home/erik/.cache/pip/http' or its parent directory is not owned by the current user and the cache has been disabled. Please check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
You are using pip version 9.0.1, however version 18.0 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.

Is it safe to perform this upgrade or will it break something? Will upgrading also fix the other (permissions) warning?