diff --git a/src/server/BreCal/validators/validation_base_utils.py b/src/server/BreCal/validators/validation_base_utils.py
index e2aad61..168d8c4 100644
--- a/src/server/BreCal/validators/validation_base_utils.py
+++ b/src/server/BreCal/validators/validation_base_utils.py
@@ -14,13 +14,13 @@ def check_if_string_has_special_characters(text:typing.Optional[str]):
     """
     if text is None:
         return False
-    return bool(set(text).difference(ascii_letters + digits + ' '))
+    return bool(set(text).difference(ascii_letters + digits + ' ' + '&' + '_' + '-'))
 
 
 def check_if_int_is_valid_flag(value, enum_object):
     if value is None: # when no value is provided, the value is considered valid.
         return False
-    
+
     # e.g., when an IntFlag has the values 1,2,4; the maximum valid value is 7
     max_int = sum([int(val) for val in list(enum_object._value2member_map_.values())])
     return 0 < value <= max_int