Lidocaine injections can cause side effects that vary from person to person. Report any side effects noticed after getting a dose of lidocaine to your doctor immediately. The most common side effects are nausea, dizziness, pain where you got the injection, confusion, sleepiness and ringing in your ears. In addition to these common side effects, you have to be on the look out for signs of an allergic reaction. Trouble breathing, a rash or itching are signs of an allergic reaction

Any medical tests, such as blood work or heart monitoring, can affect lidocaine injections. Make sure that you let all health care professionals who perform medical tests on you that you are taking lidocaine injections. In some cases, lidocaine injections may make test results indicate a problem when there in no problem or they can cause a problem to hide.