Facet joint injections and medial branch blocks

Facet joints are small joints at the back of the spine. They come in pairs, one on each side, from the neck down to the low back. They help guide and limit how the spine bends and twists.

Facet joints can become painful, often along with the wear that comes with age, or in the neck after an injury such as whiplash. The pain is usually felt in the back or neck. It can spread from the low back into the buttock or upper thigh, or from the neck to the head, shoulder, or upper arm.

Wear in the spine often shows up on scans of people with no pain at all. An exam or a standard scan, such as an MRI, cannot reliably show whether a facet joint is causing pain.

There are two main types:

• Facet joint injection. Numbing medicine, often with a steroid (a strong anti-inflammatory medicine), goes inside the joint.
• Medial branch block. Numbing medicine goes next to the medial branches, the tiny nerves that carry pain signals from the joint. Most facet joints send their signals through two of these nerves.

A medial branch block is mainly a test of whether the facet joints are a main source of the pain, and whether a longer-lasting nerve treatment called radiofrequency ablation might help.

Both are guided by a live x-ray (fluoroscopy) or a CT scan, so the medicine reaches the right spot. They can be done in the neck, the mid back, or the low back. Specialists in pain medicine, physical medicine and rehabilitation, anesthesiology, or radiology usually perform them.

The numbing medicine blocks pain signals from the joint for a short time, usually a few hours. If your usual pain eases a lot while the medicine is working, the facet joints are more likely to be a main source of it.

The test is not perfect. Some people feel relief even when the facet joints are not the main problem. That is one reason some clinics repeat the block on another day to check the result.

The steroid in a joint injection is meant to calm inflammation. It is not clear how much inflammation drives this kind of pain.

These procedures do not repair the joint. Their main value is helping you and your care team understand where the pain is coming from.

Before

Your care team will ask about blood thinners, diabetes, allergies (especially to contrast dye or numbing medicine), recent infections, and whether you could be pregnant. If you are pregnant or allergic to contrast dye, the team may change the plan, such as using a different dye, no dye, or ultrasound.

Some blood thinners are paused before some spine procedures, and some are not. The team will tell you what to do. Never stop a blood thinner on your own.

Ask your team whether to take your usual pain medicines before a test block.

Many clinics avoid medicine that makes you sleepy during a test block, because it can make the result harder to read. Many clinics ask you to bring a driver, because the numbing medicine can leave an arm or leg numb or weak for a few hours, you may feel unsteady after a neck procedure, and a driver is usually required if you are given medicine to help you relax.

During

You usually lie face down on a padded table. For some neck procedures, you may lie on your side or back. The skin is cleaned and numbed first. Most people feel a quick sting, then pressure.

A small amount of contrast dye is often used to check where the medicine will spread. The procedure usually takes less than half an hour, plus time for check-in and a short rest afterward.

After

Afterward, you may be asked to do things that usually bring on your pain, and to track your pain in a diary for several hours. Relief from the numbing medicine is expected to fade within hours. That is normal and does not mean the test failed.

Many teams count a block as positive if your pain drops by at least half. Some use a stricter cutoff, such as 80 percent. In the US, Medicare and many insurers require two blocks that each give at least 80 percent relief before they cover ablation. Most people return to light, everyday activity the next day.

As a test

People who get clear relief from a test block are more likely to be helped by radiofrequency ablation than people chosen without one. The test is still imperfect. Stricter rules, such as two blocks with a high level of relief, pick out people more likely to benefit. They also screen out some people who might have been helped. [1] [2] [6] [9]

As a treatment

The evidence that facet joint injections give lasting relief is weak. In one trial in the low back and one in the neck, steroid injected into the facet joints worked no better than salt water or numbing medicine alone. In the neck trial, relief in both groups usually lasted a week or less. A larger trial found that neither facet joint injections nor medial branch blocks worked better than salt water after one month. [5] [6] [10]

A 2025 review of many trials found that injections aimed at spinal joints give little or no extra relief compared with a sham (pretend) procedure, based on low to moderate certainty evidence. [11]

Guidelines differ. A 2025 international guideline strongly recommends against these injections for long-lasting neck or back pain, and because it also recommends against ablation, it sees no role for test blocks. Pain specialty society guidelines advise against routine use as a treatment, but support medial branch blocks as a test. The UK’s NICE guideline advises against spinal injections for low back pain, but supports a medial branch block before radiofrequency ablation. [1] [2] [12] [14]

Some people do get relief that lasts weeks or longer, though in trials people given salt water injections often did about as well. Some clinics repeat blocks as a treatment. It is hard to predict who will benefit. Most research is on the low back, with less on the neck and very little on the mid back.

Many clinicians use these procedures as one part of a plan that includes staying active and exercise.

Common and short lived

• Soreness at the injection site for a day or two.
• A short-term increase in your usual pain.
• Feeling lightheaded or faint during or right after the procedure. This usually passes with rest.
• Feeling briefly unsteady when you first stand up, especially after a procedure high in the neck.
• If a steroid is used, flushing or feeling warm, and higher blood sugar for a day or two in people with diabetes.

Less common

• Headache, especially after neck procedures.
• Brief numbness or weakness in an arm or leg if the numbing medicine reaches a nearby nerve. It wears off as the medicine does.
• Bruising or minor bleeding at the injection site.

Rare but serious

• Infection, bleeding near the spine, or nerve injury.
• In the neck, medicine entering a blood vessel has very rarely caused a stroke or spinal cord injury, mostly with a different kind of neck injection. Imaging and contrast dye help lower this risk.

Other downsides

• Relief from a facet joint injection, if it comes, is often temporary.
• Steroid doses add up. Many clinicians limit how many steroid injections someone has, partly because of effects on blood sugar and bone health.
• A test block takes time: a clinic visit, several hours of tracking your pain, and sometimes a second visit.

Get emergency care right away for numbness or weakness in the arms or legs that is getting worse or has not worn off when your team said it would, new trouble controlling your bladder or bowels, severe new back or neck pain, or, after a neck procedure, signs of a stroke such as loss of balance, vision changes, a drooping face, or trouble speaking. Call your care team the same day for a fever, redness or drainage at the injection site, or a headache that gets worse when you sit or stand.