diff --git a/config/locales/server.en.yml b/config/locales/server.en.yml
index 340cfbc7fa4..7b26f70d08c 100644
--- a/config/locales/server.en.yml
+++ b/config/locales/server.en.yml
@@ -4650,6 +4650,7 @@ en:
       restored: Restored
 
   reviewables:
+    already_handled: "Thanks, but we've already reviewed that post and determined it does not need to be flagged again."
     priorities:
       low: "Low"
       medium: "Medium"
diff --git a/lib/post_action_creator.rb b/lib/post_action_creator.rb
index b4bb11f086a..0f78ab6fb6d 100644
--- a/lib/post_action_creator.rb
+++ b/lib/post_action_creator.rb
@@ -66,6 +66,13 @@ class PostActionCreator
 
     PostAction.limit_action!(@created_by, @post, @post_action_type_id)
 
+    reviewable = Reviewable.includes(:reviewable_scores).find_by(target: @post)
+
+    if reviewable && flagging_post? && cannot_flag_again?(reviewable)
+      result.add_error(I18n.t("reviewables.already_handled"))
+      return result
+    end
+
     # create meta topic / post if needed
     if @message.present? && [:notify_moderators, :notify_user, :spam].include?(@post_action_name)
       creator = create_message_creator
@@ -115,6 +122,19 @@ class PostActionCreator
 
 private
 
+  def flagging_post?
+    PostActionType.notify_flag_type_ids.include?(@post_action_type_id)
+  end
+
+  def cannot_flag_again?(reviewable)
+    return false if @post_action_type_id == PostActionType.types[:notify_moderators]
+    flag_type_already_used = reviewable.reviewable_scores.any? { |rs| rs.reviewable_score_type == @post_action_type_id }
+    not_edited_since_last_review = @post.last_version_at.blank? || reviewable.updated_at > @post.last_version_at
+    handled_recently = reviewable.updated_at > 24.hours.ago
+
+    !reviewable.pending? && flag_type_already_used && not_edited_since_last_review && handled_recently
+  end
+
   def notify_subscribers
     if self.class.notify_types.include?(@post_action_name)
       @post.publish_change_to_clients! :acted
@@ -261,7 +281,7 @@ private
   end
 
   def create_reviewable(result)
-    return unless PostActionType.notify_flag_type_ids.include?(@post_action_type_id)
+    return unless flagging_post?
     return if @post.user_id.to_i < 0
 
     result.reviewable = ReviewableFlaggedPost.needs_review!(
diff --git a/spec/components/post_action_creator_spec.rb b/spec/components/post_action_creator_spec.rb
index 74031a639a4..dd5c97f560d 100644
--- a/spec/components/post_action_creator_spec.rb
+++ b/spec/components/post_action_creator_spec.rb
@@ -115,6 +115,38 @@ describe PostActionCreator do
         expect(score.reviewed_by).to be_blank
         expect(score.reviewed_at).to be_blank
       end
+
+      describe "When the post was already reviewed by staff" do
+        fab!(:admin) { Fabricate(:admin) }
+
+        before { reviewable.perform(admin, :ignore) }
+
+        it "fails because the post was recently reviewed" do
+          result = PostActionCreator.create(user, post, :inappropriate)
+
+          expect(result.success?).to eq(false)
+        end
+
+        it "succesfully flags the post if it was edited after being reviewed" do
+          reviewable.update!(updated_at: 25.hours.ago)
+          post.last_version_at = 30.hours.ago
+
+          result = PostActionCreator.create(user, post, :inappropriate)
+
+          expect(result.success?).to eq(true)
+          expect(result.reviewable).to be_present
+        end
+
+        it 'succesfully flags the post if it was reviewed more than 24 hours ago' do
+          reviewable.update!(updated_at: 10.minutes.ago)
+          post.last_version_at = 1.minute.ago
+
+          result = PostActionCreator.create(user, post, :inappropriate)
+
+          expect(result.success?).to eq(true)
+          expect(result.reviewable).to be_present
+        end
+      end
     end
   end
 
diff --git a/spec/models/reviewable_spec.rb b/spec/models/reviewable_spec.rb
index ff2e31fd108..9b46eb7c529 100644
--- a/spec/models/reviewable_spec.rb
+++ b/spec/models/reviewable_spec.rb
@@ -266,7 +266,7 @@ RSpec.describe Reviewable, type: :model do
     end
 
     it "triggers a notification on update" do
-      reviewable = PostActionCreator.spam(moderator, post).reviewable
+      reviewable = PostActionCreator.create(moderator, post, :inappropriate).reviewable
       reviewable.perform(moderator, :disagree)
 
       expect { PostActionCreator.spam(Fabricate(:user), post) }