This article is in our series on Medications for Pain. What are your choices? How do various medications work? Pros and cons? How about side effects?

Anesthetics are medications used to prevent sensations, particularly pain. Within this class, there are many different medications, and many ways to use these medications, including:

• Topical (through the skin), for example, a lidocaine patch. This delivers the anesthetic to nerves near the skin which are irritated. It can stay on for 12 hours or more, so you get a much longer effect than a cream.
• By mouth in pill form.
• Injection, either at a local site (local anesthesia) or covering a broader area (regional anesthesia). For injections, the anesthetic is often combined with a steroid medication.
• Intravenous (IV), for which an inpatient or outpatient hospital stay is needed.

Effect of Anesthetics: Anesthetics work by stabilizing nerve membranes, so it’s more difficult to transmit nerve signals, including pain signals.

Uses of Anesthetics: Although anesthetics are commonly used, there are few FDA-approved indications for anesthetics in specific pain disorders. The Lidoderm patch is FDA-approved for the pain of shingles (Post Herpetic Neuralgia). It’s also used for many other conditions, e.g. CRPS (Complex Regional Pain Disorder or RSD), diabetic nerve pain (Diabetic Peripheral Neuropathy), low back pain, etc. Local or regional injections are used for low back pain, other spinal pain, CRPS, etc.

Side Effects: Anesthetics used on the skin can cause skin irritation, either because of the anesthetic itself or the adhesive in the patch. Injections often cause temporary site irritation, either from the medication which is injected, or simply from injecting liquid inside your body. By their very nature, injections are also imprecise, even when your doctor uses fluoroscopy to guide the needle. Too far away from the right spot and the injection may not be effective. Too close, especially to a major nerve, and more significant nerve irritation and pain can result.

IV anesthetics can cause a drop in blood pressure or heart beat irregularities, so these must be monitored during the infusion.

Cost and Insurance Coverage
Insurance coverage for IV anesthetic treatment, for example, a lidocaine or ketamine infusion, can be very expensive. The cost is primarily for the hospital charges rather than the medication itself. However, as these treatments are in some cases very helpful, having your doctor go to bat for you with your insurance company to get them to pay for it is crucial for most patients.