diff --git a/socketio/asyncio_client.py b/socketio/asyncio_client.py
index 60dbdff..9f8d47a 100644
--- a/socketio/asyncio_client.py
+++ b/socketio/asyncio_client.py
@@ -148,7 +148,13 @@ class AsyncClient(client.Client):
                          by the client. Callback functions can only be used
                          when addressing an individual client.
 
-        Note: this method is a coroutine.
+        Note: this method is not designed to be used concurrently. If multiple
+        tasks are emitting at the same time on the same client connection, then
+        messages composed of multiple packets may end up being sent in an
+        incorrect sequence. Use standard concurrency solutions (such as a Lock
+        object) to prevent this situation.
+
+        Note 2: this method is a coroutine.
         """
         namespace = namespace or '/'
         if namespace != '/' and namespace not in self.namespaces:
@@ -214,7 +220,13 @@ class AsyncClient(client.Client):
                         the client acknowledges the event, then a
                         ``TimeoutError`` exception is raised.
 
-        Note: this method is a coroutine.
+        Note: this method is not designed to be used concurrently. If multiple
+        tasks are emitting at the same time on the same client connection, then
+        messages composed of multiple packets may end up being sent in an
+        incorrect sequence. Use standard concurrency solutions (such as a Lock
+        object) to prevent this situation.
+
+        Note 2: this method is a coroutine.
         """
         callback_event = self.eio.create_event()
         callback_args = []
diff --git a/socketio/asyncio_server.py b/socketio/asyncio_server.py
index 1e4a74a..82de504 100644
--- a/socketio/asyncio_server.py
+++ b/socketio/asyncio_server.py
@@ -118,7 +118,13 @@ class AsyncServer(server.Server):
                              to always leave this parameter with its default
                              value of ``False``.
 
-        Note: this method is a coroutine.
+        Note: this method is not designed to be used concurrently. If multiple
+        tasks are emitting at the same time to the same client connection, then
+        messages composed of multiple packets may end up being sent in an
+        incorrect sequence. Use standard concurrency solutions (such as a Lock
+        object) to prevent this situation.
+
+        Note 2: this method is a coroutine.
         """
         namespace = namespace or '/'
         room = to or room
@@ -194,6 +200,14 @@ class AsyncServer(server.Server):
                              single server process is used. It is recommended
                              to always leave this parameter with its default
                              value of ``False``.
+
+        Note: this method is not designed to be used concurrently. If multiple
+        tasks are emitting at the same time to the same client connection, then
+        messages composed of multiple packets may end up being sent in an
+        incorrect sequence. Use standard concurrency solutions (such as a Lock
+        object) to prevent this situation.
+
+        Note 2: this method is a coroutine.
         """
         if not self.async_handlers:
             raise RuntimeError(
diff --git a/socketio/client.py b/socketio/client.py
index 3c75ade..d836932 100644
--- a/socketio/client.py
+++ b/socketio/client.py
@@ -311,6 +311,12 @@ class Client(object):
                          that will be passed to the function are those provided
                          by the client. Callback functions can only be used
                          when addressing an individual client.
+
+        Note: this method is not thread safe. If multiple threads are emitting
+        at the same time on the same client connection, messages composed of
+        multiple packets may end up being sent in an incorrect sequence. Use
+        standard concurrency solutions (such as a Lock object) to prevent this
+        situation.
         """
         namespace = namespace or '/'
         if namespace != '/' and namespace not in self.namespaces:
@@ -373,6 +379,12 @@ class Client(object):
         :param timeout: The waiting timeout. If the timeout is reached before
                         the client acknowledges the event, then a
                         ``TimeoutError`` exception is raised.
+
+        Note: this method is not thread safe. If multiple threads are emitting
+        at the same time on the same client connection, messages composed of
+        multiple packets may end up being sent in an incorrect sequence. Use
+        standard concurrency solutions (such as a Lock object) to prevent this
+        situation.
         """
         callback_event = self.eio.create_event()
         callback_args = []
diff --git a/socketio/server.py b/socketio/server.py
index 4404fdd..fe8a06d 100644
--- a/socketio/server.py
+++ b/socketio/server.py
@@ -280,6 +280,12 @@ class Server(object):
                              single server process is used. It is recommended
                              to always leave this parameter with its default
                              value of ``False``.
+
+        Note: this method is not thread safe. If multiple threads are emitting
+        at the same time to the same client, then messages composed of
+        multiple packets may end up being sent in an incorrect sequence. Use
+        standard concurrency solutions (such as a Lock object) to prevent this
+        situation.
         """
         namespace = namespace or '/'
         room = to or room
@@ -352,6 +358,12 @@ class Server(object):
                              single server process is used. It is recommended
                              to always leave this parameter with its default
                              value of ``False``.
+
+        Note: this method is not thread safe. If multiple threads are emitting
+        at the same time to the same client, then messages composed of
+        multiple packets may end up being sent in an incorrect sequence. Use
+        standard concurrency solutions (such as a Lock object) to prevent this
+        situation.
         """
         if not self.async_handlers:
             raise RuntimeError(