diff --git a/src/ast/nodes/ForStatement.ts b/src/ast/nodes/ForStatement.ts
index 1e25463d10b..15385dd214b 100644
--- a/src/ast/nodes/ForStatement.ts
+++ b/src/ast/nodes/ForStatement.ts
@@ -40,7 +40,7 @@ export default class ForStatement extends StatementBase {
 
 	include(context: InclusionContext, includeChildrenRecursively: IncludeChildren) {
 		this.included = true;
-		if (this.init) this.init.include(context, includeChildrenRecursively);
+		if (this.init) this.init.includeAllDeclaredVariables(context, includeChildrenRecursively);
 		if (this.test) this.test.include(context, includeChildrenRecursively);
 		const { brokenFlow } = context;
 		if (this.update) this.update.include(context, includeChildrenRecursively);
diff --git a/src/ast/nodes/VariableDeclaration.ts b/src/ast/nodes/VariableDeclaration.ts
index 1e6f7a9a6b6..6da9123206f 100644
--- a/src/ast/nodes/VariableDeclaration.ts
+++ b/src/ast/nodes/VariableDeclaration.ts
@@ -87,6 +87,7 @@ export default class VariableDeclaration extends NodeBase {
 
 	render(code: MagicString, options: RenderOptions, nodeRenderOptions: NodeRenderOptions = BLANK) {
 		if (
+			nodeRenderOptions.isNoStatement ||
 			areAllDeclarationsIncludedAndNotExported(this.declarations, options.exportNamesByVariable)
 		) {
 			for (const declarator of this.declarations) {
diff --git a/src/ast/nodes/VariableDeclarator.ts b/src/ast/nodes/VariableDeclarator.ts
index 3a44d176183..fb1bb6efc20 100644
--- a/src/ast/nodes/VariableDeclarator.ts
+++ b/src/ast/nodes/VariableDeclarator.ts
@@ -45,6 +45,9 @@ export default class VariableDeclarator extends NodeBase {
 	): void {
 		this.included = true;
 		this.id.include(context, includeChildrenRecursively);
+		if (this.init) {
+			this.init.include(context, includeChildrenRecursively);
+		}
 	}
 
 	render(code: MagicString, options: RenderOptions) {
diff --git a/test/function/samples/unused-for-loop-declaration/_config.js b/test/function/samples/unused-for-loop-declaration/_config.js
new file mode 100644
index 00000000000..ed47aec6333
--- /dev/null
+++ b/test/function/samples/unused-for-loop-declaration/_config.js
@@ -0,0 +1,3 @@
+module.exports = {
+	description: 'does not partially tree-shake unused declarations with side-effects in for loops'
+};
diff --git a/test/function/samples/unused-for-loop-declaration/main.js b/test/function/samples/unused-for-loop-declaration/main.js
new file mode 100644
index 00000000000..4f775356dca
--- /dev/null
+++ b/test/function/samples/unused-for-loop-declaration/main.js
@@ -0,0 +1,9 @@
+let result;
+let reassigned;
+
+for (var a = (reassigned = 'reassigned'), b = 0; b < 2; b++) {
+	result = b;
+}
+
+assert.strictEqual(result, 1);
+assert.strictEqual(reassigned, 'reassigned');