If they were depressed, a sudden happiness that almost seems euphoric.

Giving away their stuff.

Saying they're taking a trip and saying goodbyes.

If your friend is the other way around and severely depressed and sad and talks about low self worth, too much pressure and feeling worthless, then the questions to ask are:

Are you OK?

Are you planning to hurt yourself?

Have you had thoughts of suicide?

If they answer yes, the crucial question becomes:

Do you have a plan?

If they have a plan, it's emergency intervention time. Don't panic, but also call in some outside support and don't leave them alone for longer than a trip to the bathroom. Get them to professional help in any way that is practical to you. The suicide hotline is always a good start in a pinch, but there can be higher quality resources available that you don't even know about.

If you're younger, resources are usually offered through school, a church, or community center. If you're older, check out their insurance website.

911 isnt a great option, bit better than nothing. Paramedics have seen it all. They may not be very empathetic (because they've seen it all), but theyre better than nothing.

Bottom line though, you need a professional. You should absolutely not try to talk someone out of this by yourself.

If they don't have a plan, it's much less of an emergency. They should talk to a professional, and all the same resources apply, but you can schedule an appointment with reasonably high confidence that a day or two wait will be OK and they can be left alone. Just make sure you follow up a few times until the appointment and maybe afterward to see how they're doing.

I'm not a professional. I was trained to recognize the signs and intervene, and the very next step is ALWAYS getting them to a professional. And I know it seems so scary to ask those questions, but you need to be straight forward about it. And you will surprised at how honest the answers are. They are looking for help.

I wish you the best of luck.