Messages can format selected iMessage text with bold, italics, underline, and strikethrough. The controls are hidden in the text-selection menu, so they are easy to miss even though no extra app is required.
This feature requires iOS 18 or later and works in iMessage conversations. Recipients need iOS 18, iPadOS 18, macOS Sequoia, or later to see the formatting.
Does This Affect You?
Use this if you want to emphasize a word, style a phrase, underline text, or strike something out before sending a blue-bubble message.
Format Text Before Sending
- Open Messages and type your message.
- Touch and hold a word to select it.
- Drag the blue handles to select the exact word, phrase, or full message you want to format.
- Tap BIU in the pop-up menu. If it is hidden, tap the arrow to reveal more menu options.
- Choose Bold, Italic, Underline, or Strikethrough.
- Apply another style if you want multiple formats on the same text.
- Send the message normally.
Compatibility Notes
Blue Bubbles Only
Formatting uses iMessage. In green SMS, MMS, or unsupported RCS conversations, the BIU formatting option does not appear.
Older Devices See Plain Text
If the recipient uses an older Apple OS, Android, or another unsupported device, the message still sends, but the formatting may appear as plain text.
Layer or Remove Formatting
Select the same text again and tap BIU to add another style. Tapping a style already applied toggles that style off.
After Sending
Once sent, formatting cannot be changed unless you use Messages editing within Apple’s allowed edit window. Edit the message, select the text, and adjust BIU formatting there.
Sources
- Apple Support: Format text in Messages on iPhone
- Apple Support: Use Messages on iPhone
- Apple Support: Send and receive messages on iPhone