diff --git a/ext/configuration.h b/ext/configuration.h
index 09d6ef0050b..dab4d686230 100644
--- a/ext/configuration.h
+++ b/ext/configuration.h
@@ -247,7 +247,9 @@ enum ddtrace_sampling_rules_format {
     CONFIG(SET, DD_DYNAMIC_INSTRUMENTATION_REDACTED_TYPES, "", .ini_change = zai_config_system_ini_change)     \
     CONFIG(INT, DD_TRACE_BAGGAGE_MAX_ITEMS, "64")                                                              \
     CONFIG(INT, DD_TRACE_BAGGAGE_MAX_BYTES, "8192")                                                            \
-    CONFIG(BOOL, DD_TRACE_INFERRED_PROXY_SERVICES_ENABLED, "false")                                             \
+    CONFIG(BOOL, DD_TRACE_INFERRED_PROXY_SERVICES_ENABLED, "false")                                            \
+    CONFIG(SET, DD_TRACE_HTTP_CLIENT_ERROR_STATUSES, "500-599", .ini_change = zai_config_system_ini_change)    \
+    CONFIG(SET, DD_TRACE_HTTP_SERVER_ERROR_STATUSES, "500-599", .ini_change = zai_config_system_ini_change)    \
     DD_INTEGRATIONS
 
 #ifndef _WIN32
diff --git a/ext/serializer.c b/ext/serializer.c
index 72cbb9ee14b..dffc321d761 100644
--- a/ext/serializer.c
+++ b/ext/serializer.c
@@ -1152,10 +1152,48 @@ static void dd_set_entrypoint_root_span_props_end(zend_array *meta, int status,
         ZVAL_STR(&status_zv, status_str);
         zend_hash_str_update(meta, ZEND_STRL("http.status_code"), &status_zv);
 
-        if (status >= 500 && !ignore_error) {
-            zval zv = {0}, *value;
-            if ((value = zend_hash_str_add(meta, ZEND_STRL("error.type"), &zv))) {
-                ZVAL_STR(value, zend_string_init(ZEND_STRL("Internal Server Error"), 0));
+        // Only check status codes if not ignoring errors
+        if (!ignore_error) {
+            bool is_error = false;
+
+            // Get server error configuration
+            zend_array *cfg = get_DD_TRACE_HTTP_SERVER_ERROR_STATUSES();
+
+            // Loop through configuration if any
+            zend_string *str_key;
+            ZEND_HASH_FOREACH_STR_KEY(cfg, str_key) {
+                if (str_key) {
+                    const char *s = ZSTR_VAL(str_key);
+
+                    // Range like "500-599"
+                    int start, end;
+                    if (sscanf(s, "%d-%d", &start, &end) == 2) {
+                        if (status >= start && status <= end) {
+                            is_error = true;
+                            break;
+                        }
+                    } else {
+                        // Single status code
+                        int code = atoi(s);
+                        if (status == code) {
+                            is_error = true;
+                            break;
+                        }
+                    }
+                }
+            } ZEND_HASH_FOREACH_END();
+
+            if (is_error) {
+                zval zv = {0}, *value;
+                if ((value = zend_hash_str_add(meta, ZEND_STRL("error.type"), &zv))) {
+                    ZVAL_STR(value, zend_string_init(ZEND_STRL("http_error"), 0));
+
+                    // Add error message and flag
+                    zval error_msg_zv = {0}, *msg_value;
+                    if ((msg_value = zend_hash_str_add(meta, ZEND_STRL("error.message"), &error_msg_zv))) {
+                        ZVAL_STR(msg_value, zend_strpprintf(0, "HTTP %d Error", status));
+                    }
+                }
             }
         }
     }
@@ -1476,7 +1514,6 @@ void transfer_data(zend_array *source, zend_array *destination, const char *key,
     }
 }
 
-
 zval *ddtrace_serialize_span_to_array(ddtrace_span_data *span, zval *array) {
     bool is_root_span = span->std.ce == ddtrace_ce_root_span_data;
     bool is_inferred_span = span->std.ce == ddtrace_ce_inferred_span_data;
diff --git a/src/DDTrace/Integrations/Curl/CurlIntegration.php b/src/DDTrace/Integrations/Curl/CurlIntegration.php
index 61304f8d294..0ef02e69905 100644
--- a/src/DDTrace/Integrations/Curl/CurlIntegration.php
+++ b/src/DDTrace/Integrations/Curl/CurlIntegration.php
@@ -275,6 +275,12 @@ public static function set_curl_attributes($span, $info) {
 
         addSpanDataTagFromCurlInfo($span, $info, Tag::HTTP_STATUS_CODE, 'http_code');
 
+        // Mark as an error if needed based on configuration
+        if (isset($info['http_code']) && !empty($info['http_code'])) {
+            $statusCode = (int)$info['http_code'];
+            HttpClientIntegrationHelper::setClientError($span, $statusCode);
+        }
+
         addSpanDataTagFromCurlInfo($span, $info, 'network.client.ip', 'local_ip');
         addSpanDataTagFromCurlInfo($span, $info, 'network.client.port', 'local_port');
 
diff --git a/src/DDTrace/Integrations/Guzzle/GuzzleIntegration.php b/src/DDTrace/Integrations/Guzzle/GuzzleIntegration.php
index 2bf782333a1..2b3589e9b23 100644
--- a/src/DDTrace/Integrations/Guzzle/GuzzleIntegration.php
+++ b/src/DDTrace/Integrations/Guzzle/GuzzleIntegration.php
@@ -50,14 +50,20 @@ function (SpanData $span, $args, $retval) use ($integration) {
                     $response = $retval;
                     if (\is_a($response, 'GuzzleHttp\Message\ResponseInterface')) {
                         /** @var \GuzzleHttp\Message\ResponseInterface $response */
-                        $span->meta[Tag::HTTP_STATUS_CODE] = $response->getStatusCode();
+                        $statusCode = $response->getStatusCode();
+                        $span->meta[Tag::HTTP_STATUS_CODE] = $statusCode;
+                        HttpClientIntegrationHelper::setClientError($span, $statusCode, $response->getReasonPhrase());
                     } elseif (\is_a($response, 'Psr\Http\Message\ResponseInterface')) {
                         /** @var \Psr\Http\Message\ResponseInterface $response */
-                        $span->meta[Tag::HTTP_STATUS_CODE] = $response->getStatusCode();
+                        $statusCode = $response->getStatusCode();
+                        $span->meta[Tag::HTTP_STATUS_CODE] = $statusCode;
+                        HttpClientIntegrationHelper::setClientError($span, $statusCode, $response->getReasonPhrase());
                     } elseif (\is_a($response, 'GuzzleHttp\Promise\PromiseInterface')) {
                         /** @var \GuzzleHttp\Promise\PromiseInterface $response */
                         $response->then(function (\Psr\Http\Message\ResponseInterface $response) use ($span) {
-                            $span->meta[Tag::HTTP_STATUS_CODE] = $response->getStatusCode();
+                            $statusCode = $response->getStatusCode();
+                            $span->meta[Tag::HTTP_STATUS_CODE] = $statusCode;
+                            HttpClientIntegrationHelper::setClientError($span, $statusCode, $response->getReasonPhrase());
                         });
                     }
                 }
@@ -84,7 +90,9 @@ function (SpanData $span, $args, $retval) use ($integration) {
                     if (\is_a($response, 'GuzzleHttp\Promise\PromiseInterface')) {
                         /** @var \GuzzleHttp\Promise\PromiseInterface $response */
                         $response->then(function (\Psr\Http\Message\ResponseInterface $response) use ($span) {
-                            $span->meta[Tag::HTTP_STATUS_CODE] = $response->getStatusCode();
+                            $statusCode = $response->getStatusCode();
+                            $span->meta[Tag::HTTP_STATUS_CODE] = $statusCode;
+                            HttpClientIntegrationHelper::setClientError($span, $statusCode, $response->getReasonPhrase());
                         });
                     }
                 }
diff --git a/src/DDTrace/Integrations/HttpClientIntegrationHelper.php b/src/DDTrace/Integrations/HttpClientIntegrationHelper.php
index 857392d67b0..fc0d01cc8df 100644
--- a/src/DDTrace/Integrations/HttpClientIntegrationHelper.php
+++ b/src/DDTrace/Integrations/HttpClientIntegrationHelper.php
@@ -10,4 +10,74 @@ class HttpClientIntegrationHelper
         Tag::NETWORK_DESTINATION_NAME,
         Tag::TARGET_HOST,
     ];
+
+    /**
+     * Determines if a given status code should be considered an error
+     * based on the DD_TRACE_HTTP_CLIENT_ERROR_STATUSES configuration.
+     *
+     * @param int $statusCode The HTTP status code to check
+     * @return bool Whether the status code should be considered an error
+     */
+    public static function isClientError($statusCode) {
+        // Get configured status codes from environment
+        $errorStatusCodes = \dd_trace_env_config("DD_TRACE_HTTP_CLIENT_ERROR_STATUSES");
+
+        // Specifically set configuration to empty
+        if (empty($errorStatusCodes)) {
+            return false;
+        }
+
+        // Custom configuration exists, use it
+        $codesList = explode(',', $errorStatusCodes);
+
+        foreach ($codesList as $item) {
+            $item = trim($item);
+
+            if (strpos($item, '-') !== false) {
+                // Range ("400-499")
+                list($start, $end) = explode('-', $item);
+                if ($statusCode >= (int)$start && $statusCode <= (int)$end) {
+                    return true;
+                }
+            } else {
+                // Single code ("404")
+                if ($statusCode == (int)$item) {
+                    return true;
+                }
+            }
+        }
+
+        // The status code isn't in any defined error range
+        return false;
+    }
+
+    /**
+     * Sets error tags on a span for HTTP client errors, if the status code
+     * matches the configuration in DD_TRACE_HTTP_CLIENT_ERROR_STATUSES.
+     *
+     * @param \DDTrace\SpanData $span The span to mark as an error
+     * @param int $statusCode The HTTP status code to check
+     * @param string|null $reasonPhrase Optional reason phrase to include in the error message
+     * @return bool Whether the span was marked as an error
+     */
+    public static function setClientError($span, $statusCode, $reasonPhrase = null) {
+        // Only set error if it's not already set
+        if (isset($span->meta[Tag::ERROR])) {
+            return false;
+        }
+
+        if (self::isClientError($statusCode)) {
+            $span->meta[Tag::ERROR_TYPE] = 'http_error';
+
+            if ($reasonPhrase) {
+                $span->meta[Tag::ERROR_MSG] = "HTTP $statusCode: $reasonPhrase";
+            } else {
+                $span->meta[Tag::ERROR_MSG] = "HTTP $statusCode Error";
+            }
+
+            return true;
+        }
+
+        return false;
+    }
 }
diff --git a/src/DDTrace/Integrations/Psr18/Psr18Integration.php b/src/DDTrace/Integrations/Psr18/Psr18Integration.php
index 2287036bbbc..d6fa8576056 100644
--- a/src/DDTrace/Integrations/Psr18/Psr18Integration.php
+++ b/src/DDTrace/Integrations/Psr18/Psr18Integration.php
@@ -37,7 +37,10 @@ function (SpanData $span, $args, $retval) use ($integration) {
 
                 if (isset($retval)) {
                     /** @var \Psr\Http\Message\ResponseInterface $retval */
-                    $span->meta[Tag::HTTP_STATUS_CODE] = $retval->getStatusCode();
+                    $statusCode = $retval->getStatusCode();
+                    $span->meta[Tag::HTTP_STATUS_CODE] = $statusCode;
+                    HttpClientIntegrationHelper::setClientError($span, $statusCode, $retval->getReasonPhrase());
+                    }
                 }
             }
         );
@@ -58,6 +61,7 @@ public function addRequestInfo(SpanData $span, $request)
         if (\dd_trace_env_config("DD_TRACE_HTTP_CLIENT_SPLIT_BY_DOMAIN")) {
             $span->service = Urls::hostnameForTag($url);
         }
+
         $span->meta[Tag::HTTP_METHOD] = $request->getMethod();
 
         if (!array_key_exists(Tag::HTTP_URL, $span->meta)) {
diff --git a/tests/ext/error_status_configuration/http_error_status_client_configuration.phpt b/tests/ext/error_status_configuration/http_error_status_client_configuration.phpt
new file mode 100644
index 00000000000..126c4007400
--- /dev/null
+++ b/tests/ext/error_status_configuration/http_error_status_client_configuration.phpt
@@ -0,0 +1,176 @@
+--TEST--
+HTTP client status code error configuration and helper functions
+--ENV--
+DD_TRACE_HTTP_CLIENT_ERROR_STATUSES=403,408-417
+--FILE--
+<?php
+// Mock the SpanData class and Tag constants to test in isolation
+class SpanData {
+    public $meta = [];
+}
+
+class Tag {
+    const ERROR = 'error';
+    const ERROR_TYPE = 'error.type';
+    const ERROR_MSG = 'error.message';
+}
+
+// Include the HttpClientIntegrationHelper class
+class HttpClientIntegrationHelper
+{
+    const PEER_SERVICE_SOURCES = [
+        'http.host',
+        'net.peer.name'
+    ];
+
+    public static function isClientError($statusCode) {
+        // Get configured status codes from environment
+        $errorStatusCodes = getenv("DD_TRACE_HTTP_CLIENT_ERROR_STATUSES");
+
+        // Return early if no configuration exists
+        if (empty($errorStatusCodes)) {
+            return false;
+        }
+
+        // Parse and check the status codes
+        $codesList = explode(',', $errorStatusCodes);
+        foreach ($codesList as $item) {
+            $item = trim($item);
+            if (empty($item)) continue;
+
+            if (strpos($item, '-') !== false) {
+                // Range ("500-599")
+                list($start, $end) = explode('-', $item);
+                if ($statusCode >= (int)$start && $statusCode <= (int)$end) {
+                    return true;
+                }
+            } else {
+                // Single code
+                if ($statusCode == (int)$item) {
+                    return true;
+                }
+            }
+        }
+
+        // No matching error status codes found
+        return false;
+    }
+
+    public static function setClientError($span, $statusCode, $reasonPhrase = null) {
+        // Only set error if it's not already set
+        if (isset($span->meta[Tag::ERROR])) {
+            return false;
+        }
+
+        if (self::isClientError($statusCode)) {
+            $span->meta[Tag::ERROR] = 1;
+            $span->meta[Tag::ERROR_TYPE] = 'http_error';
+
+            if ($reasonPhrase) {
+                $span->meta[Tag::ERROR_MSG] = "HTTP $statusCode: $reasonPhrase";
+            } else {
+                $span->meta[Tag::ERROR_MSG] = "HTTP $statusCode Error";
+            }
+
+            return true;
+        }
+
+        return false;
+    }
+}
+
+// Test isClientError directly
+echo "-- Testing isClientError with custom configuration --\n";
+echo "Status 200: " . (HttpClientIntegrationHelper::isClientError(200) ? "Error" : "Not error") . "\n";
+echo "Status 404: " . (HttpClientIntegrationHelper::isClientError(404) ? "Error" : "Not error") . "\n";
+echo "Status 403: " . (HttpClientIntegrationHelper::isClientError(403) ? "Error" : "Not error") . "\n";
+echo "Status 408: " . (HttpClientIntegrationHelper::isClientError(408) ? "Error" : "Not error") . "\n";
+echo "Status 412: " . (HttpClientIntegrationHelper::isClientError(412) ? "Error" : "Not error") . "\n";
+echo "Status 417: " . (HttpClientIntegrationHelper::isClientError(417) ? "Error" : "Not error") . "\n";
+echo "Status 500: " . (HttpClientIntegrationHelper::isClientError(500) ? "Error" : "Not error") . "\n";
+echo "Status 503: " . (HttpClientIntegrationHelper::isClientError(503) ? "Error" : "Not error") . "\n";
+echo "Status 600: " . (HttpClientIntegrationHelper::isClientError(600) ? "Error" : "Not error") . "\n";
+
+// Test setClientError method
+echo "\n-- Testing setClientError with custom configuration --\n";
+$span = new SpanData();
+$result = HttpClientIntegrationHelper::setClientError($span, 403);
+echo "Status 403: " . ($result ? "Marked as error" : "Not marked") . "\n";
+echo "Error type: " . ($span->meta[Tag::ERROR_TYPE] ?? 'none') . "\n";
+echo "Error message: " . ($span->meta[Tag::ERROR_MSG] ?? 'none') . "\n";
+
+// Test with custom reason phrase
+$span = new SpanData();
+$result = HttpClientIntegrationHelper::setClientError($span, 412, 'Precondition Failed');
+echo "\nStatus 412 with reason: " . ($result ? "Marked as error" : "Not marked") . "\n";
+echo "Error message: " . ($span->meta[Tag::ERROR_MSG] ?? 'none') . "\n";
+
+// Test non-error status
+$span = new SpanData();
+$result = HttpClientIntegrationHelper::setClientError($span, 200);
+echo "\nStatus 200: " . ($result ? "Marked as error" : "Not marked") . "\n";
+echo "Has error tag: " . (isset($span->meta[Tag::ERROR]) ? 'Yes' : 'No') . "\n";
+
+// Test already marked error
+$span = new SpanData();
+$span->meta[Tag::ERROR] = 1;
+$result = HttpClientIntegrationHelper::setClientError($span, 403);
+echo "\nPre-marked span with status 403: " . ($result ? "Marked again" : "Not marked again") . "\n";
+
+// Test with empty configuration
+putenv('DD_TRACE_HTTP_CLIENT_ERROR_STATUSES=');
+
+echo "\n-- Testing with empty configuration --\n";
+echo "Status 200: " . (HttpClientIntegrationHelper::isClientError(200) ? "Error" : "Not error") . "\n";
+echo "Status 404: " . (HttpClientIntegrationHelper::isClientError(404) ? "Error" : "Not error") . "\n";
+echo "Status 500: " . (HttpClientIntegrationHelper::isClientError(500) ? "Error" : "Not error") . "\n";
+echo "Status 599: " . (HttpClientIntegrationHelper::isClientError(599) ? "Error" : "Not error") . "\n";
+echo "Status 600: " . (HttpClientIntegrationHelper::isClientError(600) ? "Error" : "Not error") . "\n";
+
+$span = new SpanData();
+$result = HttpClientIntegrationHelper::setClientError($span, 500);
+echo "\nStatus 500 with empty config: " . ($result ? "Marked as error" : "Not marked") . "\n";
+echo "Has error tag: " . (isset($span->meta[Tag::ERROR]) ? 'Yes' : 'No') . "\n";
+
+$span = new SpanData();
+$result = HttpClientIntegrationHelper::setClientError($span, 404);
+echo "\nStatus 404 with empty config: " . ($result ? "Marked as error" : "Not marked") . "\n";
+echo "Has error tag: " . (isset($span->meta[Tag::ERROR]) ? 'Yes' : 'No') . "\n";
+?>
+--EXPECT--
+-- Testing isClientError with custom configuration --
+Status 200: Not error
+Status 404: Not error
+Status 403: Error
+Status 408: Error
+Status 412: Error
+Status 417: Error
+Status 500: Not error
+Status 503: Not error
+Status 600: Not error
+
+-- Testing setClientError with custom configuration --
+Status 403: Marked as error
+Error type: http_error
+Error message: HTTP 403 Error
+
+Status 412 with reason: Marked as error
+Error message: HTTP 412: Precondition Failed
+
+Status 200: Not marked
+Has error tag: No
+
+Pre-marked span with status 403: Not marked again
+
+-- Testing with empty configuration --
+Status 200: Not error
+Status 404: Not error
+Status 500: Not error
+Status 599: Not error
+Status 600: Not error
+
+Status 500 with empty config: Not marked
+Has error tag: No
+
+Status 404 with empty config: Not marked
+Has error tag: No
\ No newline at end of file
diff --git a/tests/ext/error_status_configuration/http_error_status_parsing.phpt b/tests/ext/error_status_configuration/http_error_status_parsing.phpt
new file mode 100644
index 00000000000..9a4d8239859
--- /dev/null
+++ b/tests/ext/error_status_configuration/http_error_status_parsing.phpt
@@ -0,0 +1,110 @@
+--TEST--
+HTTP server error status configuration parsing test
+--ENV--
+DD_TRACE_HTTP_SERVER_ERROR_STATUSES=418,429-451,503
+--FILE--
+<?php
+// Function to mimic the C implementation for checking if a status code is an error
+function isStatusError($code) {
+    // Get configured status codes from environment
+    $statusCodes = getenv('DD_TRACE_HTTP_SERVER_ERROR_STATUSES');
+    $isError = false;
+
+    // In the C implementation, when there's no environment variable,
+    // it falls back to the default "500-599" from the CONFIG macro
+    // So we need to simulate that here
+    if (!$statusCodes) {
+        $statusCodes = "500-599"; // This mimics the default in CONFIG macro
+    }
+
+    $codesList = explode(',', $statusCodes);
+    foreach ($codesList as $item) {
+        $item = trim($item);
+
+        if (strpos($item, '-') !== false) {
+            // Range like "500-599"
+            list($start, $end) = explode('-', $item);
+            if ($code >= (int)$start && $code <= (int)$end) {
+                $isError = true;
+                break;
+            }
+        } else {
+            // Single status code
+            $code_val = (int)$item;
+            if ($code == $code_val) {
+                $isError = true;
+                break;
+            }
+        }
+    }
+
+    return $isError;
+}
+
+// Function to mimic the C implementation for getting error message
+function getErrorMessage($code) {
+    return "HTTP $code Error";
+}
+
+// Test various status codes
+echo "-- With custom configuration --\n";
+echo "Status 200: " . (isStatusError(200) ? "Error" : "Not error") . "\n";
+echo "Status 418: " . (isStatusError(418) ? "Error" : "Not error") . "\n";
+if (isStatusError(418)) {
+    echo "Error message: " . getErrorMessage(418) . "\n";
+}
+echo "Status 429: " . (isStatusError(429) ? "Error" : "Not error") . "\n";
+if (isStatusError(429)) {
+    echo "Error message: " . getErrorMessage(429) . "\n";
+}
+echo "Status 451: " . (isStatusError(451) ? "Error" : "Not error") . "\n";
+if (isStatusError(451)) {
+    echo "Error message: " . getErrorMessage(451) . "\n";
+}
+echo "Status 490: " . (isStatusError(490) ? "Error" : "Not error") . "\n";
+echo "Status 500: " . (isStatusError(500) ? "Error" : "Not error") . "\n";
+echo "Status 503: " . (isStatusError(503) ? "Error" : "Not error") . "\n";
+if (isStatusError(503)) {
+    echo "Error message: " . getErrorMessage(503) . "\n";
+}
+echo "Status 600: " . (isStatusError(600) ? "Error" : "Not error") . "\n";
+
+// Now test default behavior without custom config
+putenv('DD_TRACE_HTTP_SERVER_ERROR_STATUSES=');
+
+echo "\n-- Without custom configuration (using default 500-599) --\n";
+echo "Status 200: " . (isStatusError(200) ? "Error" : "Not error") . "\n";
+echo "Status 418: " . (isStatusError(418) ? "Error" : "Not error") . "\n";
+echo "Status 500: " . (isStatusError(500) ? "Error" : "Not error") . "\n";
+if (isStatusError(500)) {
+    echo "Error message: " . getErrorMessage(500) . "\n";
+}
+echo "Status 599: " . (isStatusError(599) ? "Error" : "Not error") . "\n";
+if (isStatusError(599)) {
+    echo "Error message: " . getErrorMessage(599) . "\n";
+}
+echo "Status 600: " . (isStatusError(600) ? "Error" : "Not error") . "\n";
+?>
+--EXPECT--
+-- With custom configuration --
+Status 200: Not error
+Status 418: Error
+Error message: HTTP 418 Error
+Status 429: Error
+Error message: HTTP 429 Error
+Status 451: Error
+Error message: HTTP 451 Error
+Status 490: Not error
+Status 500: Not error
+Status 503: Error
+Error message: HTTP 503 Error
+Status 600: Not error
+
+-- Without custom configuration (using default 500-599) --
+Status 200: Not error
+Status 418: Not error
+Status 500: Error
+Error message: HTTP 500 Error
+Status 599: Error
+Error message: HTTP 599 Error
+Status 600: Not error