What could happen if i take an asprin 24 hours prior to an epidural steroid injection for a herniated disc?

Probably nothing: Studies have not demonstrated any significant risk of bleeding or hemorrhagic complications when taking Aspirin prior to an epidural steroid injection.

Don't do it!: Not a good idea. Aspirin is a blood thinner that interferes with you ability to clot blood, meaning if you start bleeding it make it very difficult to clot and stop the bleeding. Needle typically stirs up some bleeding, your epidural space is very vascular, your nerves & spinal cord lives in the area, you don't want uncontrolled bleeding there. Stop Aspirin 5-7 days before any spinal injection.

Slight increase risk: Anti-inflammatory drugs, and in particular aspirin, can have affects on platelet functioning. These proteins are in the blood and help clotting if someone is on aspirin, there is a slightly (although still very low) chance of increased bleeding risk.

If its full dose: like 325mg or higher you will be at risk for bleeding during the procedure. Typically its recommended to hold aspirin for 7 days before these types of procedures . If its 81 mg, it might be OK, but you need to speak with the doctor performing procedure to determine your risk.

It will put you: at higher risk for bleeding. If you have taken it discuss with doctor prior to the procedure.

Generally aspirin: Is not contraindicated prior to major regional such as an epidural