When you are spending real money and real hope on a procedure, you want a straight answer to three questions.
Does it work?
How will I know if it worked?
And how long will it last?
Here are straight answers, including the parts you will rarely find on a clinic page.
The short version: in published studies, somewhere between roughly half and 86% of Long COVID patients report some improvement after a stellate ganglion block (or SGB), the response is usually visible within a day or two, and while the anesthetic lasts only hours, the benefit can last weeks, months or longer. Whether it lasts depends heavily on whether your symptoms were driven by autonomic dysregulation.
What is the success rate of a stellate ganglion block?
There is no single number, and anyone giving you one without context is selling. The most quoted figure comes from a 2023 study in Cureus (Pearson et al., 41 patients), where 86% of participants reported improvement in at least one Long COVID symptom. That 86% is from the published study, not from a private tally of Dr. Groysman’s own patients. It is worth stating plainly, because the figure gets repeated everywhere as if every clinic generated it.
A more sobering number arrived in 2025. A study from Brigham and Women’s Hospital (52 patients) found that 56% saw at least some improvement, but only about 14% saw the relief clearly persist, and patients averaged around three injections.
A 2026 systematic review in Current Pain and Headache Reports pooled seven studies, found symptom improvement in all of them with response rates ranging widely, and singled out patients with prominent autonomic dysfunction as the group most likely to benefit. None of these studies used a control group, so placebo effect cannot be ruled out. The single randomized, sham-controlled trial in this space tested SGB for COVID smell distortion and found no benefit over placebo; the full evidence picture is in what the research shows.
Put together, the read is this. SGB helps a meaningful share of the right patients, the effect is real enough to keep showing up across separate studies, the durability is the weak spot, and the people most likely to win are those whose Long COVID runs through the autonomic nervous system. Success is far less about the needle than about whether you were the right patient for it.
How long does a stellate ganglion block last?
This question trips people up because two different clocks are running. The anesthetic itself wears off in a few hours. The reset it triggers can last far longer. During the block the sympathetic side is offline, the parasympathetic brake comes up, and blood flow in the brain, head, neck and chest shifts. For many people that calmer balance holds after the medication is gone.
How long it lasts can vary. Some people get lasting benefit. Others feel their old symptoms creep back after days or weeks. The body likes its previous equilibrium, even an unhealthy one, and it can pull itself back toward the stuck state. Relapse is most common after a clear trigger like a stressful stretch, another infection or surgery.
There is also a timing factor.
In people whose autonomic problem comes from other long-lasting post-viral conditions, like Lyme or chronic fatigue syndrome, rather than Long COVID, there is a possiblity of each block delivering only a small, partial gain rather than a dramatic shift.
So the real answer to “how long does it last” is: hours for the medication, potentially months or longer for the reset, and it depends on your triggers and your underlying driver.
Why some people need more than one block
A repeat block is part of how the treatment works for a sizable share of patients, not a sign of failure. In the published studies, patients commonly had more than one over time, averaging around three in the 2025 cohort. The idea is to reinforce the new, calmer autonomic balance until your body accepts it as the default.
Both sides can be blocked safely on the same day when the plan calls for it. Whether you need a second or third comes down to how your symptoms respond and how well the gains hold, not a fixed schedule. Pairing the block with vagus nerve stimulation and stress reduction can help the new state stabilize.
What a successful block feels like, step by step
During the procedure you feel pressure from the ultrasound probe on your neck, then a brief pinch and a few seconds of mild burning as the anesthetic goes in. After that the area numbs. The whole thing is usually done in under ten minutes, awake, in the office. Most people return to their normal day.
Technique is part of why the signs show up reliably. Dr. Groysman does not use the standard single-level block used for pain. He works under live ultrasound guidance, so vessels and nerves stay in view, and he blocks at two levels, C6 and C4, rather than one. The higher level reaches the sympathetic road to the brain, an addition associated with better recoveries, and it is also what makes a clean, confirmable block more likely.
Expect some harmless after-effects for the rest of that day: a lump-in-the-throat feeling, hoarseness or mild difficulty swallowing on the treated side. This comes from the anesthetic briefly reaching a nearby voice-box nerve, not from any injury, and it fades with the block. The reassuring signs, the droopy eyelid and small pupil, are doing their job in the background.
What if the block does not work?
Sometimes it does not help, and that is worth addressing directly. Assuming the block was technically sound, the usual reason SGB fails is the symptoms were not coming from dysautonomia. Long COVID has more than one mechanism. Gut dysbiosis, mitochondrial dysfunction, mast cell activation and others can drive symptoms a sympathetic block cannot reach.
This is why the evaluation matters more than the injection. Dr. Groysman uses a four-step process to identify which mechanisms are driving your case before recommending SGB. If autonomic dysfunction is the driver, the block is a strong option. If it is not, a block was never going to be the answer, and you are better off knowing that first.
Dr. Groysman’s experience with SGB
These are clinical observations, not peer-reviewed results, and they are presented that way. Across thousands of stellate ganglion blocks over his career, Dr. Groysman has not encountered the serious complications listed in the older closed-claim literature, such as bleeding, nerve injury or pneumothorax. Ultrasound guidance and near-perfect technique is a large part of why, since it keeps arteries, veins, the thyroid and nerves in view throughout.
None of this is a guarantee, and none of it cures Long COVID. It corrects an abnormal feedback loop in the autonomic nervous system for the patients whose problem lives there.
Frequently asked questions
What percentage of patients improve after SGB?
Published Long COVID studies report a wide range, from about 56% to 86% seeing some improvement, with the higher figure from a 41-patient 2023 study and a more cautious 56% (and roughly 14% with lasting relief) from a 52-patient 2025 study. Patients with autonomic dysfunction respond best. No study has had a control group yet.
How do I know the block worked?
Watch for Horner’s syndrome on the treated side within minutes: a droopy eyelid, smaller pupil, redness, a stuffy nostril and facial flushing. Three or more of these confirm a solid sympathetic block. Symptom relief itself often arrives over the next day or two, not immediately.
How long will the results last?
The anesthetic lasts hours, but the reset can last weeks, months or longer. Some people relapse after stress, illness or surgery, and may need a repeat block. Durability is the least predictable part of the procedure, and a careful provider will say so.
Is a repeat block normal?
Yes. Many patients have more than one over time. Repeats reinforce the new autonomic balance, and the need for them depends on how your symptoms respond rather than a set schedule.
Take the first step
The most important predictor of a good result is whether your symptoms are driven by autonomic dysregulation, not the technique. The way to find out is a proper evaluation.
Request a consultation with Dr. Groysman
Learn more on the main stellate ganglion block page, or read about SGB for POTS specifically.