diff --git a/common.php b/common.php
index 75916dd..aa396b8 100644
--- a/common.php
+++ b/common.php
@@ -1562,9 +1562,23 @@ function qdb_glass_symptoms_with_labels(PDO $pdo, array $config): array {
     return $rows;
 }
 
-/** Sync note German text into string_translation rows for the app. */
-function qdb_sync_question_note_strings(PDO $pdo, string $questionKey, array $config): void {
+/** Sync note German text into string_translation rows for the app. Removes rows when notes are cleared. */
+function qdb_sync_question_note_strings(
+    PDO $pdo,
+    string $questionKey,
+    array $config,
+    ?string $previousQuestionKey = null
+): void {
+    $keysToDelete = [];
+    if ($previousQuestionKey !== null) {
+        $prev = trim($previousQuestionKey);
+        if ($prev !== '' && $prev !== $questionKey) {
+            $keysToDelete[] = qdb_note_before_key($prev);
+            $keysToDelete[] = qdb_note_after_key($prev);
+        }
+    }
     if ($questionKey === '') {
+        qdb_delete_string_translation_keys($pdo, $keysToDelete);
         return;
     }
     foreach ([
@@ -1574,8 +1588,29 @@ function qdb_sync_question_note_strings(PDO $pdo, string $questionKey, array $co
         $text = trim((string)($config[$field] ?? ''));
         if ($text !== '') {
             qdb_put_translation($pdo, 'string', $stringKey, QDB_SOURCE_LANGUAGE, $text);
+        } else {
+            $keysToDelete[] = $stringKey;
         }
     }
+    qdb_delete_string_translation_keys($pdo, $keysToDelete);
+}
+
+/** @param list<string> $stringKeys */
+function qdb_delete_string_translation_keys(PDO $pdo, array $stringKeys): void {
+    $keys = [];
+    foreach ($stringKeys as $key) {
+        $key = trim((string)$key);
+        if ($key !== '') {
+            $keys[$key] = true;
+        }
+    }
+    if ($keys === []) {
+        return;
+    }
+    $list = array_keys($keys);
+    $ph = implode(',', array_fill(0, count($list), '?'));
+    $stmt = $pdo->prepare("DELETE FROM string_translation WHERE stringKey IN ($ph)");
+    $stmt->execute($list);
 }
 
 function qdb_assert_unique_question_key(PDO $pdo, string $qnID, string $questionKey, ?string $excludeQuestionID = null): void {
diff --git a/handlers/questions.php b/handlers/questions.php
index 5ada392..30ecca1 100644
--- a/handlers/questions.php
+++ b/handlers/questions.php
@@ -215,7 +215,7 @@ case 'PUT':
         $pdo->prepare("UPDATE question SET defaultText = :t, type = :ty, orderIndex = :o, isRequired = :r, configJson = :cj WHERE questionID = :id")
             ->execute([':t' => $text, ':ty' => $type, ':o' => $order, ':r' => $req, ':cj' => $configJson, ':id' => $id]);
         qdb_upsert_source_translation($pdo, 'question', $id, $text);
-        qdb_sync_question_note_strings($pdo, $questionKey, $config);
+        qdb_sync_question_note_strings($pdo, $questionKey, $config, $oldKey);
         if ($type === 'glass_scale_question') {
             qdb_sync_glass_symptom_strings($pdo, $glassSymptoms);
         }
diff --git a/tests/Integration/QuestionnaireEditingTest.php b/tests/Integration/QuestionnaireEditingTest.php
index fb6c3bf..46cd057 100644
--- a/tests/Integration/QuestionnaireEditingTest.php
+++ b/tests/Integration/QuestionnaireEditingTest.php
@@ -107,5 +107,39 @@ final class QuestionnaireEditingTest extends QdbTestCase
             'Bitte dem Klienten deutlich machen: Ohne Einwilligung keine Teilnahme.',
             $de['consent_q_note_before'] ?? null
         );
+
+        $clear = $this->api()->withToken($adminToken, 'PUT', 'questions', [
+            'questionID'  => $f->questionId,
+            'questionKey' => 'consent_q',
+            'defaultText' => 'Consent?',
+            'type'        => 'single_choice_question',
+            'isRequired'  => 1,
+            'configJson'  => json_encode(['questionKey' => 'consent_q'], JSON_UNESCAPED_UNICODE),
+            'noteBefore'  => '',
+            'noteAfter'   => '',
+        ]);
+        $this->assertApiOk($clear);
+        $this->assertGreaterThan(
+            $revAfter,
+            (int)($clear['data']['structureRevision'] ?? 0),
+            'clearing notes must bump structureRevision'
+        );
+
+        $detailCleared = $this->api()->withMobileToken($coachLogin['token'], 'GET', 'app_questionnaires', null, [
+            'id' => $f->questionnaireId,
+        ]);
+        $this->assertApiOk($detailCleared);
+        $matchedCleared = null;
+        foreach ($detailCleared['data']['questions'] ?? [] as $q) {
+            if (($q['question'] ?? '') === 'consent_q' || ($q['id'] ?? '') === 'q1') {
+                $matchedCleared = $q;
+                break;
+            }
+        }
+        $this->assertNotNull($matchedCleared);
+        $this->assertArrayNotHasKey('noteBeforeKey', $matchedCleared);
+        $this->assertArrayNotHasKey('noteAfterKey', $matchedCleared);
+        $deCleared = $detailCleared['data']['translations']['de'] ?? [];
+        $this->assertArrayNotHasKey('consent_q_note_before', $deCleared);
     }
 }