diff --git a/CHANGELOG.md b/CHANGELOG.md
index b68640aac1..6b1b261ef1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -27,6 +27,7 @@ We use *breaking* word for marking changes that are not backward compatible (rel
 - [#2970](https://github.com/thanos-io/thanos/pull/2970) Store: Upgrade minio-go/v7 to fix slowness when running on EKS.
 - [#2957](https://github.com/thanos-io/thanos/pull/2957) Rule: now sets all of the relevant fields properly; avoids a panic when `/api/v1/rules` is called and the time zone is _not_ UTC; `rules` field is an empty array now if no rules have been defined in a rule group.
 - [#2976](https://github.com/thanos-io/thanos/pull/2976) Query: Better rounding for incoming query timestamps.
+- [#2929](https://github.com/thanos-io/thanos/pull/2929) Mixin: Fix expression for 'unhealthy sidecar' alert and also increase the timeout for 10 minutes.
 
 ### Added
 
diff --git a/examples/alerts/alerts.md b/examples/alerts/alerts.md
index cb40e2a9f7..89e567a07d 100644
--- a/examples/alerts/alerts.md
+++ b/examples/alerts/alerts.md
@@ -275,7 +275,7 @@ rules:
     message: Thanos Sidecar {{$labels.job}} {{$labels.pod}} is unhealthy for {{ $value
       }} seconds.
   expr: |
-    count(time() - max(thanos_sidecar_last_heartbeat_success_time_seconds{job=~"thanos-sidecar.*"}) by (job, pod) >= 300) > 0
+    time() - max(thanos_sidecar_last_heartbeat_success_time_seconds{job=~"thanos-sidecar.*"}) by (job, pod) >= 600
   labels:
     severity: critical
 ```
diff --git a/examples/alerts/alerts.yaml b/examples/alerts/alerts.yaml
index 72c3279e49..ad5f75301b 100644
--- a/examples/alerts/alerts.yaml
+++ b/examples/alerts/alerts.yaml
@@ -258,7 +258,7 @@ groups:
       message: Thanos Sidecar {{$labels.job}} {{$labels.pod}} is unhealthy for {{
         $value }} seconds.
     expr: |
-      count(time() - max(thanos_sidecar_last_heartbeat_success_time_seconds{job=~"thanos-sidecar.*"}) by (job, pod) >= 300) > 0
+      time() - max(thanos_sidecar_last_heartbeat_success_time_seconds{job=~"thanos-sidecar.*"}) by (job, pod) >= 600
     labels:
       severity: critical
 - name: thanos-store.rules
diff --git a/examples/alerts/tests.yaml b/examples/alerts/tests.yaml
index 25df0414e4..adac87b9a4 100644
--- a/examples/alerts/tests.yaml
+++ b/examples/alerts/tests.yaml
@@ -22,47 +22,47 @@ tests:
       exp_samples:
         - labels: '{}'
           value: 120
-    - expr: max(thanos_sidecar_last_heartbeat_success_time_seconds{job="thanos-sidecar"}) by (pod)
+    - expr: max(thanos_sidecar_last_heartbeat_success_time_seconds{job="thanos-sidecar"}) by (job, pod)
       eval_time: 2m
       exp_samples:
-        - labels: '{pod="thanos-sidecar-pod-0"}'
+        - labels: '{job="thanos-sidecar", pod="thanos-sidecar-pod-0"}'
           value: 43
-        - labels: '{pod="thanos-sidecar-pod-1"}'
+        - labels: '{job="thanos-sidecar", pod="thanos-sidecar-pod-1"}'
           value: 42
-    - expr: max(thanos_sidecar_last_heartbeat_success_time_seconds{job="thanos-sidecar"}) by (pod)
-      eval_time: 5m
+    - expr: max(thanos_sidecar_last_heartbeat_success_time_seconds{job="thanos-sidecar"}) by (job, pod)
+      eval_time: 10m
       exp_samples:
-        - labels: '{pod="thanos-sidecar-pod-0"}'
+        - labels: '{job="thanos-sidecar", pod="thanos-sidecar-pod-0"}'
           value: 0
-        - labels: '{pod="thanos-sidecar-pod-1"}'
+        - labels: '{job="thanos-sidecar", pod="thanos-sidecar-pod-1"}'
           value: 0
-    - expr: max(thanos_sidecar_last_heartbeat_success_time_seconds{job="thanos-sidecar"}) by (pod)
-      eval_time: 6m
+    - expr: max(thanos_sidecar_last_heartbeat_success_time_seconds{job="thanos-sidecar"}) by (job, pod)
+      eval_time: 11m
       exp_samples:
-        - labels: '{pod="thanos-sidecar-pod-0"}'
+        - labels: '{job="thanos-sidecar", pod="thanos-sidecar-pod-0"}'
           value: 0
-        - labels: '{pod="thanos-sidecar-pod-1"}'
+        - labels: '{job="thanos-sidecar", pod="thanos-sidecar-pod-1"}'
           value: 0
-    - expr: time() - max(thanos_sidecar_last_heartbeat_success_time_seconds{job="thanos-sidecar"}) by (pod)
-      eval_time: 5m
+    - expr: time() - max(thanos_sidecar_last_heartbeat_success_time_seconds{job="thanos-sidecar"}) by (job, pod)
+      eval_time: 10m
       exp_samples:
-        - labels: '{pod="thanos-sidecar-pod-0"}'
-          value: 300
-        - labels: '{pod="thanos-sidecar-pod-1"}'
-          value: 300
-    - expr: time() - max(thanos_sidecar_last_heartbeat_success_time_seconds{job="thanos-sidecar"}) by (pod)
-      eval_time: 6m
+        - labels: '{job="thanos-sidecar", pod="thanos-sidecar-pod-0"}'
+          value: 600
+        - labels: '{job="thanos-sidecar", pod="thanos-sidecar-pod-1"}'
+          value: 600
+    - expr: time() - max(thanos_sidecar_last_heartbeat_success_time_seconds{job="thanos-sidecar"}) by (job, pod)
+      eval_time: 11m
       exp_samples:
-        - labels: '{pod="thanos-sidecar-pod-0"}'
-          value: 360
-        - labels: '{pod="thanos-sidecar-pod-1"}'
-          value: 360
-    - expr: time() - max(thanos_sidecar_last_heartbeat_success_time_seconds{job="thanos-sidecar"}) by (pod) >= 300
+        - labels: '{job="thanos-sidecar", pod="thanos-sidecar-pod-0"}'
+          value: 660
+        - labels: '{job="thanos-sidecar", pod="thanos-sidecar-pod-1"}'
+          value: 660
+    - expr: time() - max(thanos_sidecar_last_heartbeat_success_time_seconds{job="thanos-sidecar"}) by (job, pod) >= 600
       eval_time: 12m
       exp_samples:
-        - labels: '{pod="thanos-sidecar-pod-0"}'
+        - labels: '{job="thanos-sidecar", pod="thanos-sidecar-pod-0"}'
           value: 720
-        - labels: '{pod="thanos-sidecar-pod-1"}'
+        - labels: '{job="thanos-sidecar", pod="thanos-sidecar-pod-1"}'
           value: 720
   alert_rule_test:
   - eval_time: 1m
@@ -71,24 +71,48 @@ tests:
     alertname: ThanosSidecarUnhealthy
   - eval_time: 3m
     alertname: ThanosSidecarUnhealthy
-  - eval_time: 5m
+  - eval_time: 10m
     alertname: ThanosSidecarUnhealthy
     exp_alerts:
     - exp_labels:
         severity: critical
+        job: thanos-sidecar
+        pod: thanos-sidecar-pod-0
       exp_annotations:
-        message: 'Thanos Sidecar   is unhealthy for 2 seconds.'
-  - eval_time: 6m
+        message: 'Thanos Sidecar thanos-sidecar thanos-sidecar-pod-0 is unhealthy for 600 seconds.'
+    - exp_labels:
+        severity: critical
+        job: thanos-sidecar
+        pod: thanos-sidecar-pod-1
+      exp_annotations:
+        message: 'Thanos Sidecar thanos-sidecar thanos-sidecar-pod-1 is unhealthy for 600 seconds.'
+  - eval_time: 11m
     alertname: ThanosSidecarUnhealthy
     exp_alerts:
     - exp_labels:
         severity: critical
+        job: thanos-sidecar
+        pod: thanos-sidecar-pod-0
       exp_annotations:
-        message: 'Thanos Sidecar   is unhealthy for 2 seconds.'
+        message: 'Thanos Sidecar thanos-sidecar thanos-sidecar-pod-0 is unhealthy for 660 seconds.'
+    - exp_labels:
+        severity: critical
+        job: thanos-sidecar
+        pod: thanos-sidecar-pod-1
+      exp_annotations:
+        message: 'Thanos Sidecar thanos-sidecar thanos-sidecar-pod-1 is unhealthy for 660 seconds.'
   - eval_time: 12m
     alertname: ThanosSidecarUnhealthy
     exp_alerts:
     - exp_labels:
         severity: critical
+        job: thanos-sidecar
+        pod: thanos-sidecar-pod-0
+      exp_annotations:
+        message: 'Thanos Sidecar thanos-sidecar thanos-sidecar-pod-0 is unhealthy for 720 seconds.'
+    - exp_labels:
+        severity: critical
+        job: thanos-sidecar
+        pod: thanos-sidecar-pod-1
       exp_annotations:
-        message: 'Thanos Sidecar   is unhealthy for 2 seconds.'
+        message: 'Thanos Sidecar thanos-sidecar thanos-sidecar-pod-1 is unhealthy for 720 seconds.'
diff --git a/mixin/alerts/sidecar.libsonnet b/mixin/alerts/sidecar.libsonnet
index c81e2ba0a9..e1790dbac6 100644
--- a/mixin/alerts/sidecar.libsonnet
+++ b/mixin/alerts/sidecar.libsonnet
@@ -27,7 +27,7 @@
               message: 'Thanos Sidecar {{$labels.job}} {{$labels.pod}} is unhealthy for {{ $value }} seconds.',
             },
             expr: |||
-              count(time() - max(thanos_sidecar_last_heartbeat_success_time_seconds{%(selector)s}) by (job, pod) >= 300) > 0
+              time() - max(thanos_sidecar_last_heartbeat_success_time_seconds{%(selector)s}) by (job, pod) >= 600
             ||| % thanos.sidecar,
             labels: {
               severity: 'critical',