[Sammi]

Not 100% sure but I think it was this: Never inject into a vein. Always inject into a muscle.

[tsoukase]

In an intramuscular injection this is always tested by the nurse and this complication is far rarer than a nerve injury by the syringe. But in billions of cases anything can happen.

[marcosdumay]

Yes, they mandated a test to check if it was being injected into a vein.

[cogman10]

Pretty common test as well, pull the plunger back on the syringe if blood comes up you hit a vein.

A lot of drugs have this test, particularly drugs that should be injected in fat or muscle.