diff --git a/bin/doctor_karma.pl b/bin/doctor_karma.pl
index 6e4093b..cb9eada 100755
--- a/bin/doctor_karma.pl
+++ b/bin/doctor_karma.pl
@@ -59,6 +59,49 @@ sub process_message_with_text {
     if ( $text eq '+1' && defined $reply_to_message ) {
         add_karma_to_replied_message_user($message);
     }
+    if ($text eq '-1' && defined $reply_to_message) {
+        substract_karma_to_replied_message_user ($message);
+    }
+}
+
+sub substract_karma_to_replied_message_user {
+    my $message = shift;
+    my $chat_id = $message->{chat}{id};
+
+    my $reply_to_message  = $message->{reply_to_message};
+    my $user_giving_id    = $message->{from}{id};
+    my $user_receiving_id = $reply_to_message->{from}{id};
+
+    my $user_dao           = DoctorKarma::DAO::User->new( dbh => $db );
+    my $sending_karma_user = $user_dao->recover_id( id => $user_giving_id );
+
+    if ( $user_giving_id == $user_receiving_id ) {
+        $logger->log_info(<<"EOF");
+User @{[$sending_karma_user->first_name]}:@{[$sending_karma_user->username]}:@{[$sending_karma_user->id_user]} tried to substract karma to itself, refusing.
+EOF
+        $telegram->send_message(
+            chat_id => $chat_id,
+            text    => 'You cannot substract karma to yourself'
+        );
+        return;
+    }
+
+    my $receiving_karma_user =
+      $user_dao->recover_id( id => $user_receiving_id );
+    if ( !defined $receiving_karma_user ) {
+        update_user($reply_to_message);
+        $receiving_karma_user =
+          $user_dao->recover_id( id => $user_receiving_id );
+    }
+    $user_dao->substract_1_karma( user => $receiving_karma_user );
+    my $id_receptor           = $receiving_karma_user->id_user;
+    my $receptor_telegram_url = Mojo::URL->new('tg://user');
+    $receptor_telegram_url->query( id => $id_receptor );
+    $telegram->send_message(
+        chat_id => $chat_id,
+        text    =>
+"[@{[$receiving_karma_user->first_name]}]($receptor_telegram_url) has now @{[$receiving_karma_user->karma]} of karma\\."
+    );
 }
 
 sub add_karma_to_replied_message_user {
diff --git a/lib/DoctorKarma/DAO/User.pm b/lib/DoctorKarma/DAO/User.pm
index 048ed6b..535a0c9 100644
--- a/lib/DoctorKarma/DAO/User.pm
+++ b/lib/DoctorKarma/DAO/User.pm
@@ -98,6 +98,37 @@ EOF
     }
 }
 
+{
+    my $validator = validation_for(
+        params => {
+            user => { type => InstanceOf ['DoctorKarma::Model::User'] },
+        }
+    );
+
+    sub substract_1_karma {
+        my $self   = shift;
+        my %params = $validator->(@_);
+
+        my $user = $params{user};
+
+        my $db     = $self->_db;
+        my $logger = $self->_logger;
+
+        $db->do( <<'EOF', {}, $user->id_user );
+UPDATE users SET karma=karma-1 WHERE id = ?;
+EOF
+        my $user_with_new_karma = $self->recover_id( id => $user->id_user );
+        $user->karma( $user_with_new_karma->karma );
+        $logger->log_info( 'User '
+              . $user->first_name . ':'
+              . $user->username . ':'
+              . $user->id_user
+              . ' has now '
+              . $user->karma
+              . ' of karma.' );
+    }
+}
+
 {
     my $validator = validation_for(
         params => {
@@ -129,6 +160,7 @@ EOF
     }
 }
 
+
 {
     my $validator = validation_for(
         params => {
diff --git a/t/00003-model-user.t b/t/00003-model-user.t
index c68b238..4f97d61 100644
--- a/t/00003-model-user.t
+++ b/t/00003-model-user.t
@@ -5,7 +5,7 @@ use v5.30.0;
 use strict;
 use warnings;
 
-use Test::Most tests => 6;
+use Test::Most tests => 7;
 use Test::MockModule;
 use Test::MockObject;
 
@@ -36,3 +36,24 @@ BEGIN {
     is $user->first_name, $expected_firstname, 'Firstname matchs.';
     is $user->id_user, $expected_id_user, 'Id_User matchs.';
 }
+
+{
+    ## GIVEN
+    my $expected_username  = 'sergiotarxz';
+    my $expected_firstname = 'sergiotarxz';
+    my $expected_karma     = 100;
+    my $expected_id_user   = 100;
+
+    my $user = DoctorKarma::Model::User->new(
+        id_user    => $expected_id_user,
+        username   => $expected_username,
+        first_name => $expected_firstname,
+        karma      => 0,
+    );
+
+    ## WHEN
+    $user->karma($expected_karma);
+
+    ## THEN
+    is $user->karma, $expected_karma, 'The karma is the actually expected after edition.';
+}