Alt (Option) Key Not Working on Your Mac? Causes and Fixes
Quick answer: In most cases the Option key itself is fine — it has been remapped in System Settings ▸ Keyboard ▸ Keyboard Shortcuts ▸ Modifier Keys, Sticky Keys is on, or a tool such as Karabiner-Elements is intercepting it. Check those three first, then test the hardware with Keyboard Viewer.
Symptoms
| Symptom | Most likely cause |
|---|---|
| Option types nothing and runs no shortcut | Modifier Keys remapped, or a key-remapping app |
| Option+letter does not make accents | Non-standard input source selected |
| Shortcuts fire as if Option is always held | Stuck key, or Sticky Keys enabled |
| Only one Option key works | Hardware fault on that key |
| Option works in some apps only | App-level shortcut conflict |
Diagnostic checklist
Open System Settings ▸ Keyboard and turn on Keyboard Viewer (Input menu). Press each Option key and watch it highlight. If it does not light up, the problem is hardware or a low-level remap.
Note whether the problem is on the built-in keyboard, an external one, or both.
Note whether it is every app or just one.
Fixes, in order of likelihood
1. Check Modifier Keys
System Settings ▸ Keyboard ▸ Keyboard Shortcuts ▸ Modifier Keys. Pick the affected keyboard from the dropdown and make sure Option is set to Option, not "No Action" or another key. Do this for each keyboard listed.
2. Turn off Sticky Keys
System Settings ▸ Accessibility ▸ Keyboard ▸ Sticky Keys → off. Sticky Keys can leave a modifier "latched" so every keystroke acts as Option-something.
3. Rule out a remapping app
Karabiner-Elements, BetterTouchTool, hidutil scripts and some gaming software remap Option. Quit them one at a time and retest. If you use Karabiner for Excel sequences, see How to make Alt sequence keys work in Karabiner for Excel on Mac for a known-good configuration.
4. Check the input source
If accents are the only problem, the active input source may be Unicode Hex Input or a non-standard layout. System Settings ▸ Keyboard ▸ Text Input ▸ Edit and switch to your normal layout (for example ABC or British).
5. Clean or reseat the key
A physically stuck key reads as permanently held. With the Mac off, use compressed air around the key. On external keyboards, unplug and replug, or re-pair Bluetooth.
6. Test in a clean environment
Boot into Safe Mode, or create a new user account and log in. If Option works there, a login item or preference in your main account is the cause.
Prevention
Keep a note of any Modifier Keys changes you make.
Review key-remapping tools after a macOS upgrade — they often need re-approval.
If you remap for Excel, do it at the app level rather than globally.
Not actually broken: Option in Excel
If Option works everywhere except that it will not open the Excel Ribbon the way Alt does on Windows, nothing is wrong. Excel for Mac has no KeyTips. See Why Excel keyboard shortcuts do not work on Mac, or restore Windows-style sequences with the Mac Excel Shortcuts app.
FAQs
My Option key works but shortcuts still fail in one app.
That app has bound the same combination to something else, or an extension is capturing it. Check the app’s keyboard preferences.
Could this be liquid damage?
Possibly, if a single key stopped after a spill. An Apple Store or authorised service provider can test the keyboard.
Does resetting the SMC or NVRAM help?
Rarely for a single key, but it is harmless to try on Intel Macs. Apple silicon Macs have no SMC reset.