The short answer
Not in your carry-on. TSA allows one container of pepper spray of up to 4 fl oz (118 ml) in a checked bag, if it has a safety lock to prevent accidental discharge and contains no more than 2% tear gas (CS or CN). Some airlines and countries ban it entirely.
Carry-on vs checked bag
| Item | Carry-on | Checked bag |
|---|---|---|
| Pepper spray up to 4 fl oz (118 ml), safety lock | Not allowed | AllowedOne container per person |
| Pepper spray over 4 fl oz | Not allowed | Not allowed |
| Spray with more than 2% tear gas (CS/CN) | Not allowed | Not allowed |
| Pepper-spray keychain | Not allowedRemove before security | AllowedIf it has a lock |
Airlines and countries can be stricter
TSA permission is not the last word. Some airlines do not accept self-defense sprays in checked bags, and many countries, including the UK, Canada (for most sprays) and much of Europe, treat pepper spray as a prohibited weapon. If you fly internationally, leave it at home.
Frequently asked questions
What happens if I forget pepper spray in my carry-on?
TSA will take it, and you may be referred for a civil penalty. Many airports also do not let you go back to check it.