diff --git a/CHANGELOG.md b/CHANGELOG.md
index e4aae13364..597427db8a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,7 @@
 
 ### Fixes
 
+- Preserve custom `Throwable` identities when R8 optimizes Android apps ([#5881](https://github.com/getsentry/sentry-java/pull/5881))
 - Preserve single-sample ANR profile chunks so profiles remain available on ANR events ([#5872](https://github.com/getsentry/sentry-java/pull/5872))
 - Prevent inflated cold app start when the OS spawns the process in the background (e.g. FCM push) on API 35+ ([#5841](https://github.com/getsentry/sentry-java/pull/5841))
 - Avoid a CPU busy-loop when recording discarded log or metric envelopes under rate limiting ([#5835](https://github.com/getsentry/sentry-java/pull/5835))
diff --git a/sentry-android-core/proguard-rules.pro b/sentry-android-core/proguard-rules.pro
index 4cd76f9a20..a66e472b07 100644
--- a/sentry-android-core/proguard-rules.pro
+++ b/sentry-android-core/proguard-rules.pro
@@ -29,6 +29,11 @@
 # https://developer.android.com/studio/build/shrink-code#decode-stack-trace
 -keepattributes LineNumberTable,SourceFile
 
+# Preserve distinct runtime identities for custom Throwables. R8 horizontal class merging can
+# otherwise merge unrelated exception classes, causing the runtime type and retraced frames to
+# disagree. Unused Throwables may still be removed, and retained Throwables may still be obfuscated.
+-keep,allowshrinking,allowobfuscation class * extends java.lang.Throwable
+
 # Keep Classnames for integrations
 -keepnames class * implements io.sentry.Integration