What does it do if you take medicine after the expiration date?

I’ve actually asked a pharmacist this question before. Tablets may be fine for years after expiring. There are only a few that are harmful, that is not one of them. But it may have lost potency.

Hi, sirsydow!
It depends on how over date it is and how it's been stored. Most medications are still good for months and sometimes even longer. Most will not go "bad" but they often lose potency and quickly become ineffective.
It's probably not a good idea to start to take a medicine which has not been prescribed recently and specifically for a current condition especially benzodiazepines like alprazolam. They can be addictive for some people even at low doses and can have immediate and long-term adverse reactions.
I'd suggest calling your doctor to get professional advice and dosages. You might also want to discuss other treatments that are better for long-term use.
Best regards and I hope you're feeling better quickly.
Wildcat