How to Remove the Subject Line in Messages on the iPhone

To remove the subject line in Messages on an iPhone, open Settings, tap Apps, tap Messages, then turn off Show Subject Field. On iOS 17 and earlier there is no Apps step: go to Settings > Messages and turn off the same switch. The extra Subject box then disappears from the area where you type a message.

The subject line is an optional second text box that sits above the normal message box. It works like the subject of an email. Most people never use it, and when it is on it is easy to type a whole message into the wrong box.

Before You Start

• Which iPhones: the setting is part of the built-in Messages app, so you do not need a particular iPhone model.
• Which iOS versions: Apple moved app settings into an Apps list in iOS 18. Apple’s current iPhone User Guide gives the route to Messages settings as Settings, then Apps, then Messages. Older versions list Messages on the main Settings screen.
• What changes: only the box where you type. Turning the switch off does not delete conversations, block messages, or change how messages are sent.
• What Apple documents: Apple’s guide explains how to reach Messages settings, but it does not describe the Show Subject Field switch itself. The exact position of the switch in the list can differ between iOS versions, so look for the label rather than counting rows.

How to Turn Off the Subject Line (iOS 18 and Later)

1. Open the Settings app. It is the gray gear icon on the Home Screen.
2. Scroll to the bottom of the main Settings list and tap Apps. You will see an alphabetical list of the apps on your iPhone.
3. Tap Messages. You can scroll to the M section or use the search field at the top of the list.
4. Scroll down until you see Show Subject Field. It is usually grouped with other text message options, such as Character Count.
5. Tap the switch next to Show Subject Field so it is no longer green. A gray switch means the subject line is off.
6. Leave Settings. There is no Save button. The change applies as soon as you tap the switch.

Apple’s own instructions for reaching this screen are in Set up Messages on iPhone.

How to Turn Off the Subject Line (iOS 17 and Earlier)

1. Open Settings.
2. Scroll down the main list and tap Messages.
3. Scroll down to the SMS/MMS section.
4. Tap the switch next to Show Subject Field to turn it off.

The screenshot below is from an older version of iOS. The colors and spacing have changed since then, but the switch has the same name.

How to Confirm the Subject Line Is Gone

1. Open the Messages app.
2. Open any conversation, or start a new message.
3. Look at the typing area at the bottom of the screen. You should see one text box only, with no Subject box above it.

Messages you already sent with a subject are not changed. They stay in the conversation the way they were sent.

How to Bring the Subject Line Back

Go back to the same screen and turn Show Subject Field on. The switch turns green and the Subject box returns the next time you write a message. You can switch it on and off as often as you like.

If you only want a subject now and then, you can also leave the switch on and simply leave the Subject box empty. A message with an empty subject is sent as a normal message.

What the Subject Field Does

With the switch on, every message you write has two boxes: Subject on top and the regular message box underneath. Text typed in the Subject box is sent as a heading for the message, and it generally shows in bold above the rest of the text.

The switch has long been listed with the SMS/MMS options. SMS is a plain text message sent through your carrier. MMS is the carrier format used for pictures, group texts, and other richer content. A text message that carries a subject may be sent as MMS instead of SMS, and some carrier plans treat the two differently. If that matters to you, turning the subject line off avoids the question.

If you were using the Subject box only to get bold text, there is now a documented way to do that. On iOS 18 and later, you can select text in an iMessage and apply bold, italic, underline, or strikethrough. Apple explains the steps in Format text and animate messages on iPhone. That formatting works in iMessage conversations only, and the other person needs iOS 18 or later (or a matching Apple device) to see it.

Troubleshooting

I cannot find Messages in Settings

On iOS 18 and later, Messages is no longer on the main Settings screen. Scroll all the way down, tap Apps, then tap Messages. On older versions, Messages is in the main list with the other Apple apps.

I cannot find Show Subject Field

Open Settings, tap the search field, and type subject. If a matching setting appears, tap it to jump straight there. Apple describes this search in Find settings on iPhone. If nothing appears, scroll slowly through the whole Messages settings screen, because the switch sits well below the iMessage options at the top.

The Subject box is still there after I turned the switch off

• Go back to the setting and check that the switch is gray, not green.
• Close the Messages app and open it again. Apple’s steps are in Quit and reopen an app on iPhone.
• If the box is still showing, restart the iPhone and look again.
• Make sure you are looking at Apple’s Messages app. Other messaging apps have their own settings, and this switch does not affect them.

The switch keeps turning back on

The setting should stay where you leave it. If someone else uses your iPhone, they may have turned it on again. If you recently restored the phone from a backup or set up a new iPhone from an old one, your older settings may have come back with it, so check the switch once more.

Frequently Asked Questions

Does turning off the subject line delete any messages?

No. The switch only hides the Subject box in the typing area. Your conversations, attachments, and contacts stay exactly as they are.

Will I still see subjects that other people send me?

Yes. The setting controls what you see when you write a message. If someone sends you a message with a subject, it can still show up with that subject in the conversation.

Does this work for iMessage and regular text messages?

There is one switch for the Messages app. When it is off, the Subject box is hidden in blue iMessage conversations and in green text message conversations alike. If you are not sure which kind you are sending, see our guide to the difference between green and blue texts on an iPhone.

Why did the subject line appear in the first place?

The subject line only shows when Show Subject Field is on. It is normally off, so the most likely reason is that the switch was tapped by accident while changing another Messages setting, or it was carried over from an older iPhone.

Is the setting the same on an iPad?

The iPad version of Messages has a setting with the same name. On iPadOS 18 and later, look in Settings > Apps > Messages.

Can I remove the subject from one message without changing the setting?

Yes. Leave the Subject box empty, or delete what you typed there before you tap Send. Only the text in the main message box is sent.

Next Steps

While you are on the Messages settings screen, you can tidy up a few other things. You can hide the contact pictures next to text messages, or read about how to turn on iMessage on an iPhone if your messages keep sending as green texts.

If you need to send a longer, more formal message with a real subject, email may be a better fit. Our guide on how to email a text message from an iPhone shows one way to do it. For group conversations, see how to add someone to a group text on an iPhone.