If your iPhone's Messages app shows two text boxes when you write a message, a gray Subject line on top and the message field below, the Show Subject Field setting is turned on. It is easy to enable by accident and makes messages look cluttered, and it can even turn simple texts into MMS messages. This guide shows how to remove the subject line on an iPhone 7 and every other iPhone, and explains what the setting actually does.
Quick Answer
Open Settings > Messages (on iOS 18 and later, Settings > Apps > Messages), scroll to the SMS/MMS section, and turn off Show Subject Field. The subject line disappears from the Messages app immediately.
Step-by-Step Instructions
- Open the Settings app.
- Scroll down and tap Messages. On iOS 18 or later, tap Apps first, then Messages. (The iPhone 7 supports up to iOS 15, so it uses Settings > Messages.)
- Scroll to the SMS/MMS section.
- Tap the Show Subject Field switch to turn it off (the switch turns gray).
- Open Messages and start a new message to confirm there is only one text field.
Tip: you can also swipe down on the Settings home screen and search for Subject to jump to the setting.
What the Subject Field Does
The subject field lets you add a title to a message, similar to an email subject. It is part of the SMS/MMS options, and when you add a subject:
- Messages sent over SMS may be converted to MMS, which can use mobile data or count differently on some older or prepaid plans.
- Recipients on other phones may see the subject in bold or as a separate line.
- iMessage recipients see the subject in bold above the message.
Most people never need it, so turning it off gives you the simpler, single-field message box.
What Happens After You Turn It Off
- New messages show one text box.
- Past messages that included a subject still show it.
- Messages you send will no longer include a subject, so they stay as regular SMS or iMessage texts.
Other Messages Settings Worth Checking
| Setting | What it does |
|---|---|
| Character Count | Shows how many characters you have typed in SMS messages |
| MMS Messaging | Allows picture and video messages over SMS; turning it off blocks MMS |
| Group Messaging | Keeps SMS group chats together with replies going to everyone |
| Send as SMS | Sends a regular text when iMessage is unavailable |
| Send Read Receipts | Lets iMessage senders see when you have read their messages |
Troubleshooting
I do not see Show Subject Field
Make sure you are looking in the SMS/MMS section. The option is available on all current iPhones, but some carriers may change which SMS/MMS options appear. Update iOS in Settings > General > Software Update if the section is missing.
The subject line is still there
Force close Messages (swipe up from the bottom, or double-click the Home button on iPhone 7, and swipe the app away), then reopen it. If it persists, restart your iPhone.
Someone else's messages have subjects
That setting is on their phone. Your setting only affects the messages you write.
Frequently Asked Questions
Why did a subject line suddenly appear in my messages?
Show Subject Field was turned on, possibly by accident, after a settings reset, or when setting up a new iPhone from a backup.
Does turning off the subject field delete anything?
No. It only changes how the message box looks for new messages.
Can I add a subject to just one message?
Only by turning the setting on temporarily, adding the subject, and turning it off again afterward.
Is this the same on newer iPhones?
Yes. The setting works the same way on all iPhones. The only difference is its location in iOS 18 and later, under Settings > Apps > Messages.
Summary
- Open Settings > Messages (or Settings > Apps > Messages on iOS 18 and later).
- Scroll to SMS/MMS.
- Turn off Show Subject Field.
Kermit Matthews is a freelance writer based in Philadelphia, Pennsylvania with more than a decade of experience writing technology guides. He has a Bachelor’s and Master’s degree in Computer Science and has spent much of his professional career in IT management.
He specializes in writing content about iPhones, Android devices, Microsoft Office, and many other popular applications and devices.