diff --git a/backend/db/db.py b/backend/db/db.py
index 207b2ff..5bfb2e6 100644
--- a/backend/db/db.py
+++ b/backend/db/db.py
@@ -579,23 +579,29 @@ def ensure_mongodb_indexes(client=None, db_name=None):
             coll.create_index(keys, **kwargs)
 
 
-# Clear test collections at import time so tests start with a clean slate.
+# Clear test data at import time so tests start with a clean slate.
 if os.environ.get('DB_ENV', 'prod') == 'test':
-    child_db.truncate()
-    task_db.truncate()
-    routine_db.truncate()
-    routine_items_db.truncate()
-    routine_schedules_db.truncate()
-    routine_extensions_db.truncate()
-    reward_db.truncate()
-    image_db.truncate()
-    pending_reward_db.truncate()
-    pending_confirmations_db.truncate()
-    users_db.truncate()
-    tracking_events_db.truncate()
-    child_overrides_db.truncate()
-    chore_schedules_db.truncate()
-    task_extensions_db.truncate()
-    refresh_tokens_db.truncate()
-    push_subscriptions_db.truncate()
-    digest_action_tokens_db.truncate()
+    if USE_MONGODB:
+        # Drop the entire MongoDB test database for a fresh start. Only do this
+        # for clearly test/e2e database names as a safety guard.
+        if _mongo_db_name and _mongo_db_name.endswith(('_test', '_e2e')):
+            get_mongo_client().drop_database(_mongo_db_name)
+    else:
+        child_db.truncate()
+        task_db.truncate()
+        routine_db.truncate()
+        routine_items_db.truncate()
+        routine_schedules_db.truncate()
+        routine_extensions_db.truncate()
+        reward_db.truncate()
+        image_db.truncate()
+        pending_reward_db.truncate()
+        pending_confirmations_db.truncate()
+        users_db.truncate()
+        tracking_events_db.truncate()
+        child_overrides_db.truncate()
+        chore_schedules_db.truncate()
+        task_extensions_db.truncate()
+        refresh_tokens_db.truncate()
+        push_subscriptions_db.truncate()
+        digest_action_tokens_db.truncate()