diff --git a/mysql/content.md b/mysql/content.md
index 0b7575067..49b9ffc8a 100644
--- a/mysql/content.md
+++ b/mysql/content.md
@@ -128,6 +128,8 @@ As an alternative to passing sensitive information via environment variables, \_
 $ docker run --name some-mysql -e MYSQL_ROOT_PASSWORD_FILE=/run/secrets/mysql-root -d mysql:tag
 ```
 
+Currently, this is only supported for MYSQL_ROOT_PASSWORD, MYSQL_ROOT_HOST, MYSQL_DATABASE, MYSQL_USER, and MYSQL_PASSWORD.
+
 # Initializing a fresh instance
 
 When a container is started for the first time, a new database with the specified name will be created and initialized with the provided configuration variables. Furthermore, it will execute files with extensions `.sh`, `.sql` and `.sql.gz` that are found in `/docker-entrypoint-initdb.d`. Files will be executed in alphabetical order. You can easily populate your %%REPO%% services by [mounting a SQL dump into that directory](https://docs.docker.com/engine/tutorials/dockervolumes/#mount-a-host-file-as-a-data-volume) and provide [custom images](https://docs.docker.com/reference/builder/) with contributed data. SQL files will be imported by default to the database specified by the `MYSQL_DATABASE` variable.