diff --git a/syncapi/consumers/eduserver_sendtodevice.go b/syncapi/consumers/eduserver_sendtodevice.go
index d95067921..6e774b5b4 100644
--- a/syncapi/consumers/eduserver_sendtodevice.go
+++ b/syncapi/consumers/eduserver_sendtodevice.go
@@ -105,8 +105,6 @@ func (s *OutputSendToDeviceEventConsumer) onMessage(msg *sarama.ConsumerMessage)
 		return err
 	}
 
-	util.GetLogger(context.TODO()).Infof("Stored send-to-device message at position %d", streamPos)
-
 	s.stream.Advance(streamPos)
 	s.notifier.OnNewSendToDevice(
 		output.UserID,
diff --git a/syncapi/storage/interface.go b/syncapi/storage/interface.go
index 8c6c5c120..a51ab4e0d 100644
--- a/syncapi/storage/interface.go
+++ b/syncapi/storage/interface.go
@@ -119,11 +119,13 @@ type Database interface {
 	// added to the unsigned section of the output event.
 	StreamEventsToEvents(device *userapi.Device, in []types.StreamEvent) []*gomatrixserverlib.HeaderedEvent
 	// SendToDeviceUpdatesForSync returns a list of send-to-device updates. It returns the
-	// relevant events, and it automatically truncates old events once we advance past the
-	// stream position of the old send-to-device messages.
+	// relevant events within the given ranges for the supplied user ID and device ID.
 	SendToDeviceUpdatesForSync(ctx context.Context, userID, deviceID string, from, to types.StreamPosition) (pos types.StreamPosition, events []types.SendToDeviceEvent, err error)
 	// StoreNewSendForDeviceMessage stores a new send-to-device event for a user's device.
 	StoreNewSendForDeviceMessage(ctx context.Context, userID, deviceID string, event gomatrixserverlib.SendToDeviceEvent) (types.StreamPosition, error)
+	// CleanSendToDeviceUpdates removes all send-to-device messages BEFORE the specified
+	// from position, preventing the send-to-device table from growing indefinitely.
+	CleanSendToDeviceUpdates(ctx context.Context, userID, deviceID string, before types.StreamPosition) (err error)
 	// GetFilter looks up the filter associated with a given local user and filter ID.
 	// Returns a filter structure. Otherwise returns an error if no such filter exists
 	// or if there was an error talking to the database.
diff --git a/syncapi/storage/shared/syncserver.go b/syncapi/storage/shared/syncserver.go
index 572d60ae3..5b06aabcd 100644
--- a/syncapi/storage/shared/syncserver.go
+++ b/syncapi/storage/shared/syncserver.go
@@ -907,21 +907,24 @@ func (d *Database) SendToDeviceUpdatesForSync(
 	if err != nil {
 		return from, nil, fmt.Errorf("d.SendToDevice.SelectSendToDeviceMessages: %w", err)
 	}
-
 	// If there's nothing to do then stop here.
 	if len(events) == 0 {
 		return to, nil, nil
 	}
+	return lastPos, events, nil
+}
 
-	// If we've advanced past this stream position for this
-	// user+device combo then clean up behind.
+func (d *Database) CleanSendToDeviceUpdates(
+	ctx context.Context,
+	userID, deviceID string, before types.StreamPosition,
+) (err error) {
 	if err = d.Writer.Do(d.DB, nil, func(txn *sql.Tx) error {
-		return d.SendToDevice.DeleteSendToDeviceMessages(ctx, txn, userID, deviceID, from)
+		return d.SendToDevice.DeleteSendToDeviceMessages(ctx, txn, userID, deviceID, before)
 	}); err != nil {
 		logrus.WithError(err).Errorf("Failed to clean up old send-to-device messages for user %q device %q", userID, deviceID)
+		return err
 	}
-
-	return lastPos, events, nil
+	return nil
 }
 
 // getMembershipFromEvent returns the value of content.membership iff the event is a state event
diff --git a/syncapi/streams/stream_sendtodevice.go b/syncapi/streams/stream_sendtodevice.go
index 8ad7b456a..a3aaf3d7d 100644
--- a/syncapi/streams/stream_sendtodevice.go
+++ b/syncapi/streams/stream_sendtodevice.go
@@ -38,9 +38,18 @@ func (p *SendToDeviceStreamProvider) IncrementalSync(
 		req.Log.WithError(err).Error("p.DB.SendToDeviceUpdatesForSync failed")
 		return from
 	}
-	// Add the updates into the sync response.
-	for _, event := range events {
-		req.Response.ToDevice.Events = append(req.Response.ToDevice.Events, event.SendToDeviceEvent)
+
+	if len(events) > 0 {
+		// Clean up old send-to-device messages from before this stream position.
+		if err := p.DB.CleanSendToDeviceUpdates(req.Context, req.Device.UserID, req.Device.ID, from); err != nil {
+			req.Log.WithError(err).Error("p.DB.CleanSendToDeviceUpdates failed")
+			return from
+		}
+
+		// Add the updates into the sync response.
+		for _, event := range events {
+			req.Response.ToDevice.Events = append(req.Response.ToDevice.Events, event.SendToDeviceEvent)
+		}
 	}
 
 	return lastPos