diff --git a/CHANGELOG.md b/CHANGELOG.md
index 642dd8d..b8ebc81 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+### 5.0.1
+
+- `login_required` now always checks for a valid session cookie before falling back to a DEBUG_USER in development environments.
+
 # 5.0.0 (breaking change)
 
 - `fsd_utils.toggles` has been made an optional extra, so its dependencies are not installed automatically. If your
diff --git a/fsd_utils/authentication/decorators.py b/fsd_utils/authentication/decorators.py
index 4acf9ce..1eeacaa 100644
--- a/fsd_utils/authentication/decorators.py
+++ b/fsd_utils/authentication/decorators.py
@@ -11,6 +11,7 @@
 from fsd_utils.authentication.utils import validate_token_rs256
 from jwt import ExpiredSignatureError
 from jwt import PyJWTError
+from werkzeug.exceptions import HTTPException
 
 from .config import config_var_auth_host
 from .config import config_var_logout_url_override
@@ -107,15 +108,18 @@ def login_required(
 
     @wraps(f)
     def _wrapper(*args, **kwargs):
-        if current_app.config.get(
-            "FLASK_ENV"
-        ) == "development" and current_app.config.get("DEBUG_USER_ON"):
-            g.account_id = current_app.config.get("DEBUG_USER_ACCOUNT_ID")
-            g.user = User(**current_app.config.get("DEBUG_USER"))
-        else:
+        try:
             token_payload = _check_access_token(return_app=return_app)
             g.account_id = token_payload.get("accountId")
             g.user = User.set_with_token(token_payload)
+        except HTTPException as e:
+            if current_app.config.get(
+                "FLASK_ENV"
+            ) == "development" and current_app.config.get("DEBUG_USER_ON"):
+                g.account_id = current_app.config.get("DEBUG_USER_ACCOUNT_ID")
+                g.user = User(**current_app.config.get("DEBUG_USER"))
+            else:
+                raise e
 
         g.logout_url = _build_logout_url(return_app)
         g.is_authenticated = True
diff --git a/pyproject.toml b/pyproject.toml
index ab52284..ce98651 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -5,7 +5,7 @@ build-backend = "setuptools.build_meta"
 [project]
 name = "funding-service-design-utils"
 
-version = "5.0.0"
+version = "5.0.1"
 
 authors = [
   { name="DLUHC", email="FundingServiceDesignTeam@levellingup.gov.uk" },