Lidocaine concentration in plasma (serum/plasma)

Why This Test Is Done

Your healthcare provider may order this test if you’ve recently received a lidocaine injection (e.g., for pain relief, anesthesia, or nerve block) and need to check how your body is handling it. It can also be done if you’re experiencing unusual side effects like dizziness, confusion, or irregular heartbeat, which may signal too much lidocaine in your system.

What to Expect Before the Test

No special preparation is needed. You may have a blood draw from a vein in your arm, similar to other routine blood tests. If you’re on other medications or have health conditions, let your provider know before the test.

How the Test Results Are Interpreted

Results are typically reported as a concentration in micrograms per milliliter (µg/mL) or milligrams per liter (mg/L). Your provider will compare these results to your clinical picture and other factors (like dose, time since administration) to guide care.

Possible Side Effects or Risks

While rare, very high lidocaine levels can cause serious side effects, such as seizures, heart rhythm problems, or low blood pressure. If you notice symptoms like nausea, vision changes, or extreme dizziness, seek medical attention immediately.