diff --git a/sources/BaseAPI/API/Commands/BuiltInCommands/ACommandSideEffects.uc b/sources/BaseAPI/API/Commands/BuiltInCommands/ACommandSideEffects.uc
new file mode 100644
index 0000000..e28845f
--- /dev/null
+++ b/sources/BaseAPI/API/Commands/BuiltInCommands/ACommandSideEffects.uc
@@ -0,0 +1,193 @@
+/**
+ * Author: dkanus
+ * Home repo: https://www.insultplayers.ru/git/AcediaFramework/AcediaCore
+ * License: GPL
+ * Copyright 2023 Anton Tarasenko
+ *------------------------------------------------------------------------------
+ * This file is part of Acedia.
+ *
+ * Acedia is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Acedia is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Acedia.  If not, see <https://www.gnu.org/licenses/>.
+ */
+class ACommandSideEffects extends Command;
+
+// Maps `UserID` to `ArrayList` with side effects listed for that player last time
+var private HashTable displayedLists;
+
+protected function Constructor() {
+    super.Constructor();
+    displayedLists = _.collections.EmptyHashTable();
+}
+
+protected function Finalizer() {
+    super.Finalizer();
+    _.memory.Free(displayedLists);
+    displayedLists = none;
+}
+
+protected function BuildData(CommandDataBuilder builder) {
+    builder.Name(P("sideeffects"));
+    builder.Group(P("core"));
+    builder.Summary(P("Displays information about current side effects."));
+    builder.Describe(P("This command allows to display current side effects, optionally filtering"
+        @ "them by specified package names."));
+    builder.OptionalParams();
+    builder.ParamTextList(P("package_names"));
+
+    builder.SubCommand(P("show"));
+    builder.Describe(P("This sub-command is only usable after side effects have been shown"
+        @ "at least once. It takes an index from the last displayed list and displays a verbose"
+        @ "information about it."));
+    builder.ParamInteger(P("side_effect_number"));
+
+    builder.Option(P("verbose"));
+    builder.Describe(P("Display verbose information about each side effect."));
+}
+
+protected function Executed(CallData arguments, EPlayer instigator) {
+    local UserID playerID;
+    local array<SideEffect> relevantSideEffects;
+    local ArrayList packagesList, storedSideEffectsList;
+
+    playerID = instigator.GetUserID();
+    if (arguments.subCommandName.IsEmpty()) {
+        relevantSideEffects = _.sideEffects.GetAll();
+        packagesList = arguments.parameters.GetArrayList(P("package_names"));
+        FilterSideEffects(/*out*/ relevantSideEffects, packagesList);
+        _.memory.Free(packagesList);
+        DisplaySideEffects(relevantSideEffects, arguments.options.HasKey(P("verbose")));
+        // Store new side effect list
+        storedSideEffectsList = _.collections.NewArrayList(relevantSideEffects);
+        displayedLists.SetItem(playerID, storedSideEffectsList);
+        _.memory.FreeMany(relevantSideEffects);
+        _.memory.Free(storedSideEffectsList);
+    } else {
+        ShowInfoFor(playerID, arguments.parameters.GetInt(P("side_effect_number")));
+    }
+    _.memory.Free(playerID);
+}
+
+private function FilterSideEffects(out array<SideEffect> sideEffects, ArrayList allowedPackages) {
+    local int i, j;
+    local int packagesLength;
+    local bool matchedPackage;
+    local Text nextSideEffectPackage, nextAllowedPackage;
+
+    if (allowedPackages == none)            return;
+    if (allowedPackages.GetLength() <= 0)   return;
+
+    packagesLength = allowedPackages.GetLength();
+    while (i < sideEffects.length) {
+        nextSideEffectPackage = sideEffects[i].GetPackage();
+        matchedPackage = false;
+        for (j = 0; j < packagesLength; j += 1) {
+            nextAllowedPackage = allowedPackages.GetText(j);
+            if (nextAllowedPackage.Compare(nextSideEffectPackage, SCASE_INSENSITIVE)) {
+                matchedPackage = true;
+                _.memory.Free(nextAllowedPackage);
+                break;
+            }
+            _.memory.Free(nextAllowedPackage);
+        }
+        if (!matchedPackage) {
+            sideEffects.Remove(i, 1);
+        } else {
+            i += 1;
+        }
+        _.memory.Free(nextSideEffectPackage);
+    }
+}
+
+private function DisplaySideEffects(array<SideEffect> toDisplay, bool verbose) {
+    local int i;
+    local MutableText nextPrefix;
+
+    if (toDisplay.length <= 0) {
+        callerConsole.Write(F("List of side effects is {$TextNeutral empty}."));
+    }
+    for (i = 0; i < toDisplay.length; i += 1) {
+        nextPrefix = _.text.FromIntM(i + 1);
+        nextPrefix.Append(P("."));
+        DisplaySideEffect(toDisplay[i], nextPrefix, verbose);
+        _.memory.Free(nextPrefix);
+    }
+}
+
+private function DisplaySideEffect(SideEffect toDisplay, BaseText prefix, bool verbose) {
+    local Text effectName, effectDescription, effectPackage, effectSource, effectStatus;
+
+    if (toDisplay == none) {
+        return;
+    }
+    if (prefix != none) {
+        callerConsole.Write(prefix);
+        callerConsole.Write(P(" "));
+    }
+    effectName = toDisplay.GetName();
+    effectPackage = toDisplay.GetPackage();
+    effectSource = toDisplay.GetSource();
+    effectStatus = toDisplay.GetStatus();
+    callerConsole.UseColor(_.color.TextEmphasis);
+    callerConsole.Write(P("["));
+    callerConsole.Write(effectPackage);
+    callerConsole.Write(P(" \\ "));
+    callerConsole.Write(effectSource);
+    callerConsole.Write(P("] "));
+    callerConsole.ResetColor();
+    callerConsole.Write(effectName);
+    callerConsole.Write(P(" {"));
+    callerConsole.Write(effectStatus);
+    callerConsole.WriteLine(P("}"));
+    if (verbose) {
+        effectDescription = toDisplay.GetDescription();
+        callerConsole.WriteBlock(effectDescription);
+    }
+    _.memory.Free5(effectName, effectDescription, effectPackage, effectSource, effectStatus);
+}
+
+private function ShowInfoFor(UserID playerID, int sideEffectIndex) {
+    local SideEffect toDisplay;
+    local ArrayList sideEffectList;
+
+    if (playerID == none) {
+        return;
+    }
+    if (sideEffectIndex <= 0) {
+        callerConsole.WriteLine(F("Specified side effect index {$TextNegative isn't positive}!"));
+        return;
+    }
+    sideEffectList = displayedLists.GetArrayList(playerID);
+    if (sideEffectList == none) {
+        callerConsole.WriteLine(F("{$TextNegative Cannot display} side effect by index without"
+            @ "first listing them. Call {$TextEmphasis sideeffects} command without"
+            @ "{$TextEmphasis show} subcommand first."));
+        return;
+    }
+    if (sideEffectIndex > sideEffectList.GetLength()) {
+        callerConsole.WriteLine(F("Specified side effect index is {$TextNegative out of bounds}."));
+        _.memory.Free(sideEffectList);
+        return;
+    }
+    // Above we checked that `sideEffectIndex` lies within `[0; sideEffectList.GetLength()]` segment
+    // This means that `sideEffectIndex - 1` points at non-`none` value
+    toDisplay = SideEffect(sideEffectList.GetItem(sideEffectIndex - 1));
+    if (!_.sideEffects.IsRegistered(toDisplay)) {
+        callerConsole.UseColorOnce(_.color.TextWarning);
+        callerConsole.WriteLine(P("Selected side effect is no longer active!"));
+    }
+    DisplaySideEffect(toDisplay, none, true);
+    _.memory.Free2(toDisplay, sideEffectList);
+}
+
+defaultproperties {
+}
\ No newline at end of file
diff --git a/sources/BaseAPI/API/Commands/Commands_Feature.uc b/sources/BaseAPI/API/Commands/Commands_Feature.uc
index 7480bcd..df540a4 100644
--- a/sources/BaseAPI/API/Commands/Commands_Feature.uc
+++ b/sources/BaseAPI/API/Commands/Commands_Feature.uc
@@ -110,6 +110,7 @@ protected function OnEnabled() {
     RegisterCommand(class'ACommandHelp');
     RegisterCommand(class'ACommandNotify');
     RegisterCommand(class'ACommandVote');
+    RegisterCommand(class'ACommandSideEffects');
     if (_.environment.IsDebugging()) {
         RegisterCommand(class'ACommandFakers');
     }
diff --git a/sources/BaseAPI/API/SideEffects/SideEffectAPI.uc b/sources/BaseAPI/API/SideEffects/SideEffectAPI.uc
index 7e58b91..3317c59 100644
--- a/sources/BaseAPI/API/SideEffects/SideEffectAPI.uc
+++ b/sources/BaseAPI/API/SideEffects/SideEffectAPI.uc
@@ -120,6 +120,24 @@ public function SideEffect Add_S(
     return newSideEffect;
 }
 
+/// Checks whether specified [`SideEffect`] is currently active.
+///
+/// Check is done via contents and not instance equality.
+/// Returns `true` if specified [`SideEffect`] is currently active and `false` otherwise.
+public function bool IsRegistered(SideEffect sideEffectToCheck) {
+    local int i;
+
+    if (sideEffectToCheck == none)          return false;
+    if (!sideEffectToCheck.IsInitialized()) return false;
+
+    for (i = 0; i < activeSideEffects.length; i += 1) {
+        if (activeSideEffects[i].IsEqual(sideEffectToCheck)) {
+            return true;
+        }
+    }
+    return false;
+}
+
 /// Adds a new side effect to the list of active side effects.
 ///
 /// This method will fail if its argument is `none`, non-initialized or a side effect with that
diff --git a/sources/Users/User.uc b/sources/Users/User.uc
index 4eae0ad..ccce20a 100644
--- a/sources/Users/User.uc
+++ b/sources/Users/User.uc
@@ -176,6 +176,22 @@ public final function bool SetPersistentData(
     return result;
 }
 
+public function bool IsEqual(Object other) {
+    local User otherUser;
+
+    if (id == none)             return false;
+    otherUser = User(other);
+    if (otherUser == none)      return false;
+    if (otherUser.id == none)   return false;
+
+    return id.IsEqual(otherUser.id);
+}
+
+protected function int CalculateHashCode() {
+    // If `id` is `none`, then caller `User` shouldn't be used at all
+    return id.GetHashCode();
+}
+
 defaultproperties
 {
 }
\ No newline at end of file