diff --git a/src/anthropic/resources/completions.py b/src/anthropic/resources/completions.py
index d34a42f2..7369f485 100644
--- a/src/anthropic/resources/completions.py
+++ b/src/anthropic/resources/completions.py
@@ -11,6 +11,7 @@
 from ..types import completion_create_params
 from .._types import NOT_GIVEN, Body, Query, Headers, NotGiven
 from .._utils import (
+    is_given,
     required_args,
     maybe_transform,
     async_maybe_transform,
@@ -18,6 +19,7 @@
 from .._compat import cached_property
 from .._resource import SyncAPIResource, AsyncAPIResource
 from .._response import to_streamed_response_wrapper, async_to_streamed_response_wrapper
+from .._constants import DEFAULT_TIMEOUT
 from .._streaming import Stream, AsyncStream
 from .._base_client import make_request_options
 from ..types.completion import Completion
@@ -53,7 +55,7 @@ def create(
         extra_headers: Headers | None = None,
         extra_query: Query | None = None,
         extra_body: Body | None = None,
-        timeout: float | httpx.Timeout | None | NotGiven = 600,
+        timeout: float | httpx.Timeout | None | NotGiven = NOT_GIVEN,
     ) -> Completion:
         """[Legacy] Create a Text Completion.
 
@@ -157,7 +159,7 @@ def create(
         extra_headers: Headers | None = None,
         extra_query: Query | None = None,
         extra_body: Body | None = None,
-        timeout: float | httpx.Timeout | None | NotGiven = 600,
+        timeout: float | httpx.Timeout | None | NotGiven = NOT_GIVEN,
     ) -> Stream[Completion]:
         """[Legacy] Create a Text Completion.
 
@@ -261,7 +263,7 @@ def create(
         extra_headers: Headers | None = None,
         extra_query: Query | None = None,
         extra_body: Body | None = None,
-        timeout: float | httpx.Timeout | None | NotGiven = 600,
+        timeout: float | httpx.Timeout | None | NotGiven = NOT_GIVEN,
     ) -> Completion | Stream[Completion]:
         """[Legacy] Create a Text Completion.
 
@@ -365,8 +367,10 @@ def create(
         extra_headers: Headers | None = None,
         extra_query: Query | None = None,
         extra_body: Body | None = None,
-        timeout: float | httpx.Timeout | None | NotGiven = 600,
+        timeout: float | httpx.Timeout | None | NotGiven = NOT_GIVEN,
     ) -> Completion | Stream[Completion]:
+        if not is_given(timeout) and self._client.timeout == DEFAULT_TIMEOUT:
+            timeout = 600
         return self._post(
             "/v1/complete",
             body=maybe_transform(
@@ -419,7 +423,7 @@ async def create(
         extra_headers: Headers | None = None,
         extra_query: Query | None = None,
         extra_body: Body | None = None,
-        timeout: float | httpx.Timeout | None | NotGiven = 600,
+        timeout: float | httpx.Timeout | None | NotGiven = NOT_GIVEN,
     ) -> Completion:
         """[Legacy] Create a Text Completion.
 
@@ -523,7 +527,7 @@ async def create(
         extra_headers: Headers | None = None,
         extra_query: Query | None = None,
         extra_body: Body | None = None,
-        timeout: float | httpx.Timeout | None | NotGiven = 600,
+        timeout: float | httpx.Timeout | None | NotGiven = NOT_GIVEN,
     ) -> AsyncStream[Completion]:
         """[Legacy] Create a Text Completion.
 
@@ -627,7 +631,7 @@ async def create(
         extra_headers: Headers | None = None,
         extra_query: Query | None = None,
         extra_body: Body | None = None,
-        timeout: float | httpx.Timeout | None | NotGiven = 600,
+        timeout: float | httpx.Timeout | None | NotGiven = NOT_GIVEN,
     ) -> Completion | AsyncStream[Completion]:
         """[Legacy] Create a Text Completion.
 
@@ -731,8 +735,10 @@ async def create(
         extra_headers: Headers | None = None,
         extra_query: Query | None = None,
         extra_body: Body | None = None,
-        timeout: float | httpx.Timeout | None | NotGiven = 600,
+        timeout: float | httpx.Timeout | None | NotGiven = NOT_GIVEN,
     ) -> Completion | AsyncStream[Completion]:
+        if not is_given(timeout) and self._client.timeout == DEFAULT_TIMEOUT:
+            timeout = 600
         return await self._post(
             "/v1/complete",
             body=await async_maybe_transform(
diff --git a/src/anthropic/resources/messages.py b/src/anthropic/resources/messages.py
index 21fd4285..8b6ab106 100644
--- a/src/anthropic/resources/messages.py
+++ b/src/anthropic/resources/messages.py
@@ -12,6 +12,7 @@
 from ..types import message_create_params
 from .._types import NOT_GIVEN, Body, Query, Headers, NotGiven
 from .._utils import (
+    is_given,
     required_args,
     maybe_transform,
     async_maybe_transform,
@@ -19,6 +20,7 @@
 from .._compat import cached_property
 from .._resource import SyncAPIResource, AsyncAPIResource
 from .._response import to_streamed_response_wrapper, async_to_streamed_response_wrapper
+from .._constants import DEFAULT_TIMEOUT
 from .._streaming import Stream, AsyncStream
 from .._base_client import make_request_options
 from ..lib.streaming import MessageStreamManager, AsyncMessageStreamManager
@@ -62,7 +64,7 @@ def create(
         extra_headers: Headers | None = None,
         extra_query: Query | None = None,
         extra_body: Body | None = None,
-        timeout: float | httpx.Timeout | None | NotGiven = 600,
+        timeout: float | httpx.Timeout | None | NotGiven = NOT_GIVEN,
     ) -> Message:
         """
         Create a Message.
@@ -325,7 +327,7 @@ def create(
         extra_headers: Headers | None = None,
         extra_query: Query | None = None,
         extra_body: Body | None = None,
-        timeout: float | httpx.Timeout | None | NotGiven = 600,
+        timeout: float | httpx.Timeout | None | NotGiven = NOT_GIVEN,
     ) -> Stream[RawMessageStreamEvent]:
         """
         Create a Message.
@@ -588,7 +590,7 @@ def create(
         extra_headers: Headers | None = None,
         extra_query: Query | None = None,
         extra_body: Body | None = None,
-        timeout: float | httpx.Timeout | None | NotGiven = 600,
+        timeout: float | httpx.Timeout | None | NotGiven = NOT_GIVEN,
     ) -> Message | Stream[RawMessageStreamEvent]:
         """
         Create a Message.
@@ -851,8 +853,10 @@ def create(
         extra_headers: Headers | None = None,
         extra_query: Query | None = None,
         extra_body: Body | None = None,
-        timeout: float | httpx.Timeout | None | NotGiven = 600,
+        timeout: float | httpx.Timeout | None | NotGiven = NOT_GIVEN,
     ) -> Message | Stream[RawMessageStreamEvent]:
+        if not is_given(timeout) and self._client.timeout == DEFAULT_TIMEOUT:
+            timeout = 600
         return self._post(
             "/v1/messages",
             body=maybe_transform(
@@ -966,7 +970,7 @@ async def create(
         extra_headers: Headers | None = None,
         extra_query: Query | None = None,
         extra_body: Body | None = None,
-        timeout: float | httpx.Timeout | None | NotGiven = 600,
+        timeout: float | httpx.Timeout | None | NotGiven = NOT_GIVEN,
     ) -> Message:
         """
         Create a Message.
@@ -1229,7 +1233,7 @@ async def create(
         extra_headers: Headers | None = None,
         extra_query: Query | None = None,
         extra_body: Body | None = None,
-        timeout: float | httpx.Timeout | None | NotGiven = 600,
+        timeout: float | httpx.Timeout | None | NotGiven = NOT_GIVEN,
     ) -> AsyncStream[RawMessageStreamEvent]:
         """
         Create a Message.
@@ -1492,7 +1496,7 @@ async def create(
         extra_headers: Headers | None = None,
         extra_query: Query | None = None,
         extra_body: Body | None = None,
-        timeout: float | httpx.Timeout | None | NotGiven = 600,
+        timeout: float | httpx.Timeout | None | NotGiven = NOT_GIVEN,
     ) -> Message | AsyncStream[RawMessageStreamEvent]:
         """
         Create a Message.
@@ -1755,8 +1759,10 @@ async def create(
         extra_headers: Headers | None = None,
         extra_query: Query | None = None,
         extra_body: Body | None = None,
-        timeout: float | httpx.Timeout | None | NotGiven = 600,
+        timeout: float | httpx.Timeout | None | NotGiven = NOT_GIVEN,
     ) -> Message | AsyncStream[RawMessageStreamEvent]:
+        if not is_given(timeout) and self._client.timeout == DEFAULT_TIMEOUT:
+            timeout = 600
         return await self._post(
             "/v1/messages",
             body=await async_maybe_transform(