SGB, or stellate ganglion block, is a medical procedure in which a local anesthetic is injected into a cluster of nerves on the side of the neck to calm an overactive stress response. Originally developed decades ago for pain conditions, it has gained attention more recently as a treatment for PTSD, anxiety, and certain other conditions driven by a nervous system stuck in overdrive. The procedure takes only a few minutes, and some patients report feeling relief within hours.
How the Procedure Works
The stellate ganglion is a bundle of sympathetic nerves located near the C6 vertebra, roughly at the base of your neck. These nerves are part of the “fight or flight” system that controls your heart rate, sweating, blood pressure, and stress hormones. When a doctor performs an SGB, they inject a small amount of local anesthetic (typically 6 to 8 mL) directly around this nerve bundle using ultrasound guidance to avoid nearby arteries and other critical structures.
You’ll lie on your back with your mouth slightly open to relax the front of your neck. The doctor uses color Doppler ultrasound to map the blood vessels and anatomy in real time before inserting the needle. In experienced hands, the actual injection takes one to two minutes. The anesthetic temporarily blocks nerve signals passing through the stellate ganglion, which is thought to lower levels of norepinephrine, the brain’s primary stress chemical, and reduce excessive nerve growth in the sympathetic system. This essentially acts like a reset for the body’s stress thermostat.
Some protocols call for a single injection on one side, while others use bilateral injections (both sides of the neck), with at least 12 hours between the two for safety. Bilateral blocks are never done simultaneously because blocking the nerves on both sides at once could cause the vocal cords to close, creating a breathing emergency.
What It Feels Like Afterward
The most immediate and expected effect is something called Horner’s syndrome on the same side as the injection: a drooping eyelid, a constricted pupil, and a warm, flushed feeling in the face and arm. This is actually a sign that the block is working, and it resolves on its own as the anesthetic wears off, usually within several hours. Some people also notice a temporary hoarse voice or a sensation of a lump in the throat.
Serious complications are rare but have been documented. Because the injection site is near major blood vessels, accidental intravascular injection can cause seizures or, in extremely rare cases, cardiac arrest. This is why ultrasound guidance has become standard: it lets the doctor see exactly where the needle tip is relative to the carotid and vertebral arteries.
SGB for PTSD
PTSD involves a state of chronic hyperarousal, where the brain’s fear and threat-processing centers stay activated long after the original trauma. This keeps the sympathetic nervous system running at a high baseline, flooding the body with stress hormones. SGB appears to interrupt that cycle by temporarily blocking the nerve pathway that feeds this hyperactive response.
The evidence is promising but still mixed. Early case series reported rapid clinical improvement in 70% to 75% of PTSD patients. However, these were unblinded studies without placebo controls, meaning patients and doctors both knew the treatment was real. When researchers conducted a randomized controlled trial comparing SGB to a saline injection, the results were more modest. After one round of treatment, PTSD symptom improvement ranged from about 5% to 15%, and after a second round, 12% to 21%. These improvements were not significantly better than the placebo group. Larger trials funded by the U.S. Army are underway to provide a clearer answer.
The gap between case series and controlled trials is worth understanding. Placebo effects are powerful in psychiatric conditions, and the physical sensation of Horner’s syndrome could amplify a patient’s expectation of improvement. That doesn’t mean SGB is ineffective for PTSD. It means the current evidence hasn’t definitively proven it works better than a sham injection in rigorous testing.
SGB for Anxiety
A large case series of 285 patients found more striking results for generalized anxiety. Patients’ anxiety scores dropped by an average of 9 points on a standard 21-point scale within one week, which is more than double the threshold considered clinically meaningful. About 80% of patients showed significant improvement at one week, and 75.5% still showed improvement at one month.
Bilateral injections produced larger improvements than one-sided blocks. Patients who received injections on both sides saw an average drop of 9.9 points at one week, compared to 7.5 points for those who received a single-side injection. These are notable numbers, though this study lacked a placebo control group, so the same caveats about expectation effects apply.
SGB for Long COVID Symptoms
After anecdotal reports suggested SGB could help with post-COVID smell distortion (parosmia), researchers at Washington University in St. Louis ran a proper randomized, double-blinded trial. They enrolled 48 participants who had experienced parosmia for an average of about 30 to 35 months after their COVID infection. At three months, 43% of the SGB group responded to treatment, but so did 38% of the placebo group. The difference was not statistically meaningful, and the researchers concluded that SGB should not be recommended for COVID-induced parosmia.
Who Should Not Get SGB
If you take blood thinners such as warfarin, clopidogrel, or direct oral anticoagulants, your doctor will likely ask you to stop them several days before the procedure. The injection site is surrounded by major blood vessels, and anticoagulation raises the risk of a neck hematoma. In hospital settings where SGB is used for life-threatening heart rhythm problems, doctors sometimes proceed despite anticoagulation because the benefit outweighs the risk, but that’s a different situation than elective treatment.
People with certain anatomical variations in their neck arteries may need a modified approach or may not be good candidates. This is one reason the pre-procedure ultrasound scan matters: it can reveal unusual branching of the vertebral artery or other structures that would make a standard approach riskier.
Cost and Insurance Coverage
A one-sided SGB typically costs up to $1,200, and a bilateral block runs up to $2,000. When SGB is used for pain conditions like complex regional pain syndrome, insurance may cover it. However, most insurance plans do not cover SGB when it’s performed for PTSD or anxiety, since it’s still considered off-label for psychiatric indications. That means you’ll likely pay out of pocket if you’re seeking it for stress-related conditions. Some clinics offer payment plans, but it’s worth confirming coverage before scheduling.
How Long Relief Lasts
The anesthetic itself wears off within hours, but the therapeutic effects appear to outlast the drug. In the anxiety case series, improvements held steady from one week through at least one month. Some patients report benefits lasting several months, while others find that symptoms gradually return and seek repeat injections. There is no established protocol for how many treatments are optimal or how often they should be repeated. Clinicians who offer SGB for PTSD and anxiety often frame it as one component of a broader treatment plan that includes therapy, rather than a standalone cure.