A stellate ganglion block is an injection of numbing medicine into a cluster of nerves in the neck that helps control the body’s fight-or-flight responses. The medicine itself wears off within hours, but the relief people come for often lasts weeks or months. So there are two timelines: a short one for the drug and a longer, less predictable one for your symptoms. For many people, one injection is only the start, because repeat blocks can stretch the relief further.
The Numbing Effect Wears Off Within Hours
Right after the injection, many people notice a droopy eyelid, a small pupil and less sweating on one side of the face.1OpenAnesthesia. Stellate Ganglion Block Your doctor reads these, along with a warmer hand on that side, as a sign the medicine reached the right nerves.2OpenAnesthesia. Stellate Ganglion Block These signs usually fade within 4 to 6 hours.3OpenAnesthesia. Stellate Ganglion Block In one reported case, adding the steroid dexamethasone kept the droopy-eye sign for about 43 hours.4Cureus. Intravenous Dexamethasone as an Adjuvant to Stellate Ganglion Block for Refractory Cerebral Vasospasm After Aneurysmal Subarachnoid Haemorrhage: A Case Report How long the signs last depends on the drug, the dose and how close the medicine sits to the nerve, so two people who get the same injection can see them fade at somewhat different times.
The drug used sets how long the nerve stays numbed. Short-acting lidocaine blocked the nerve for about 1.5 to 2 hours in one comparison, while ropivacaine lasted about 5 to 6 hours in the same comparison.5PubMed Central. Comparison of lidocaine and ropivacaine stellate ganglion blockade in treating upper limb postherpetic neuralgia For heart-rhythm emergencies, a single shot is described as lasting about 3 to 12 hours depending on the drug.6ASRA Pain Medicine. Stellate Ganglion Block for Ventricular Tachycardia Longer-acting bupivacaine has calmed nerve activity for 6 hours to a week in some patients.7PubMed Central. Efficacy of Stellate Ganglion Blockade in Managing Electrical Storm: A Systematic Review It’s reasonable to ask your doctor which drug they plan to use.
The first day can look more alarming than it is. The droopy eye and a hoarse voice are expected and temporary. Many people are watched briefly in the clinic and then sent home the same day. Plan for someone to drive you, since you may feel off afterward.
Watching the eye signs fade tells you the drug is wearing off, not that the treatment has stopped working, and it says nothing yet about how your pain, sleep or anxiety will go. Relief outlasts the drug because the block seems to interrupt an overactive stress signal, and the nerves may not fully return to that state. Some people feel a change within minutes to hours, and others notice nothing until days later, so the day of the injection is too early to judge. Note how you feel at the end of the first day, then keep watching over the following weeks.
How Long Relief Lasts for Pain, PTSD and Other Conditions
For CRPS (complex regional pain syndrome), a long-lasting nerve pain condition often in an arm or hand, most studies show relief of about 2 to 4 weeks.8PubMed Central. Efficacy of stellate ganglion interventions for complex regional pain syndrome in the upper limb—A systematic review and meta-analysis A couple of studies found meaningful pain reduction lasting up to 6 months.9PubMed Central. Efficacy of stellate ganglion interventions for complex regional pain syndrome in the upper limb—A systematic review and meta-analysis In one reported case, pain relief was still holding at a 2-week checkup.10PubMed Central. Unusual case of contralateral Horner’s syndrome following stellate-ganglion block: a case report and review of the literature For CRPS, success often means less pain and swelling and better use of the hand or arm, which can make physical therapy easier in the weeks after a block.
The VA says SGB may ease PTSD symptoms for at least a few weeks.11US Department of Veterans Affairs. Stellate Ganglion Block Treatment For PTSD At VA In a controlled trial, two blocks two weeks apart cut symptom scores about twice as much as a fake injection over 8 weeks.12JAMA Psychiatry. Effect of Stellate Ganglion Block Treatment on Posttraumatic Stress Disorder Symptoms: A Randomized Clinical Trial In one clinic’s records, nearly all patients given blocks on both sides of the neck still had improvement at six months, averaging about 55%.13Clinical and Translational Neuroscience. Long-Term Durability of Bilateral Two-Level Stellate Ganglion Blocks in Posttraumatic Stress Disorder: A Six-Month Retrospective Analysis For PTSD, doctors usually look at changes in symptom scores such as hyperarousal, sleep and nightmares, not a cure.
People with long COVID reported less fatigue, brain fog, poor sleep and anxiety a month or more after a block.14PubMed. Reduction of long COVID symptoms after stellate ganglion block: A retrospective chart review study In another group, only two patients had symptoms come back during follow-up, one after a new viral illness.15PubMed Central. Stellate Ganglion Block Relieves Long COVID-19 Symptoms in 86% of Patients: A Retrospective Cohort Study These findings come from reviewing past records, and the block may help only some people.16PubMed. Reduction of long COVID symptoms after stellate ganglion block: A retrospective chart review study
In a controlled trial, women had milder, fewer hot flashes over 12 weeks, with the biggest effect in the first 4 weeks.17PubMed Central. Effects of stellate ganglion block on perimenopausal hot flashes: a randomized controlled trial In breast cancer survivors, hot flash scores dropped 64% at week 1 and were still 47% lower at week 24.18PubMed. Stellate ganglion block for the management of hot flashes and sleep disturbances in breast cancer survivors: an uncontrolled experimental study with 24 weeks of follow-up A fake injection cut hot flashes by about a third for three months in one trial, so part of early relief may be expectation.19PubMed Central. Effects of Stellate Ganglion Block on Vasomotor Symptoms: Findings from a Randomized, Controlled Clinical Trial in Postmenopausal Women The real block still pulled clearly ahead for moderate to severe hot flashes by months 4 to 6.20PubMed Central. Effects of Stellate Ganglion Block on Vasomotor Symptoms: Findings from a Randomized, Controlled Clinical Trial in Postmenopausal Women Here the measure is how many flashes you have and how severe they are, so some can remain even when the block is working.
The numbers differ so much because studies vary in which drug they used, how many injections they gave and when they measured symptoms. Small studies and single case reports are less dependable than controlled trials that compare against a fake injection.
The useful question is how much better the real block did than a fake one, not just how much people improved. This applies most to symptoms like hot flashes and PTSD, which are strongly shaped by stress and expectation.
These durations come from groups, so your result could be shorter or longer, and some people get little or no benefit. Relief often fades gradually, with symptoms creeping back over days or weeks instead of ending abruptly. Some people see a partial improvement, such as sleeping better or fewer flashbacks, instead of full disappearance of symptoms.
A simple symptom diary helps you and your doctor see when relief fades. Ask your clinic what result they would count as working, and when they would want to see you again if it does not.
Repeat Blocks Often Last Longer
More than half of people treated for upper-body CRPS needed more than one block, most often two given 3 weeks apart.21PubMed Central. A study of the efficacy of stellate ganglion blocks in complex regional pain syndromes of the upper body One review describes typical relief of three to six months per injection, with repeat blocks sometimes needed.22PubMed Central. A Review of Stellate Ganglion Block as an Adjunctive Treatment Modality After a block for dangerous heart rhythms, the problem returns in up to 44% of patients unless longer-term treatment follows.23ASRA Pain Medicine. Stellate Ganglion Block for Ventricular Tachycardia
Relief can also build with each block. In a small group with hot flashes, the first block gave 2 to 5 weeks of complete relief, and a second gave 4 to 18 weeks.24PubMed. Stellate ganglion blockade provides relief from menopausal hot flashes: a case report series Two women who had a third block reported 15 and 48 weeks of relief.25PubMed. Stellate ganglion blockade provides relief from menopausal hot flashes: a case report series
A first block shows your doctor whether your symptoms respond to this nerve at all, so even a brief benefit is useful information. A very brief first result does not reliably predict what a second will do, and some people still get little benefit, so the decision is made between you and your doctor.
Spacing varies. Some clinics give a planned series, such as two injections a few weeks apart, while others wait until symptoms return. Patients in one series went back when mild symptoms started coming back. Ask whether yours is a set series or as needed, whether a short first result means stopping or trying again, and whether insurance covers repeat injections.
Some PTSD clinics inject both sides at two neck levels, and the long-lasting six-month results came from that approach. Ask which approach your clinic uses and why.
Repeating stops making sense when two or three well-placed blocks give no clear benefit, and many doctors will then consider a different treatment. Each injection carries small risks, so the benefit should be weighed against them each time.
Ways Doctors Try to Make Relief Last Longer
Adding the steroid dexamethasone to bupivacaine has lengthened its effect, by about 41% in a related nerve block.26Malta Medical Journal. Serial Ultrasound-guided Stellate Ganglion Block using Bupivacaine, Dexamethasone, and Methylcobalamin to Treat Complex Regional Pain Syndrome type II: A Case Report Ad Interim Adding magnesium to lidocaine and dexamethasone gave longer pain relief and less need for pain pills after breast surgery.27The Medical Journal of Cairo University. Magnesium Sulfate as an Adjuvant in Ultrasound Guided Stellate Ganglion Block for Post Mastectomy Pain Syndrome The added drug is mixed into the same syringe, so it needs no extra needle stick. Because these results came from other nerve blocks, they may not carry over to the stellate ganglion exactly. It is fair to ask whether the add-on is standard at that clinic or varies by doctor.
Radiofrequency treatment uses a needle tip that sends energy to the nerve instead of just numbing it. For shingles nerve pain, pulsed radiofrequency kept pain lower out to 6 months, while a standard block’s benefit faded after 1 month.28PubMed Central. CT-Guided Stellate Ganglion Pulsed Radiofrequency Stimulation for Facial and Upper Limb Postherpetic Neuralgia For pain after breast removal, heat-based radiofrequency helped more people than the pulsed kind at 1, 3 and 6 months.29Pain Physician. Thermal Versus Super Voltage Pulsed Radiofrequency of Stellate Ganglion in Post-Mastectomy Neuropathic Pain Syndrome: A Prospective Randomized Trial
Radiofrequency is usually considered when blocks keep working but wear off too fast, so it is a next step rather than a first treatment. Pulsed radiofrequency uses short bursts that do not heat the tissue much, while the heat-based kind deliberately warms and damages a small area of nerve. Because that alters the nerve more permanently, it calls for a careful talk about risks and benefits. Results for shingles and post-breast-surgery pain may not apply to PTSD or CRPS.
Placement matters too. Ultrasound guidance reached the target in 9 of 10 practice injections versus 6 of 10 with X-ray guidance.30PubMed. Ultrasound Versus Fluoroscopy for Stellate Ganglion Block: A Cadaveric Study Ultrasound lets the doctor see blood vessels, muscles and the needle in real time, so asking whether your doctor uses it is reasonable. Those figures come from practice injections, so they show better accuracy in a test, not proof of longer relief for patients. Most of this evidence is small and specific to one condition.
How Long Side Effects Last
Hoarseness is the most commonly reported side effect, in about 28% of people who had one.31PubMed Central. Complications associated with stellate ganglion nerve block: a systematic review Most reported problems happened during or shortly after the injection, and most people with complications recovered without long-term harm.32PubMed Central. Complications associated with stellate ganglion nerve block: a systematic review The droopy-eye sign is expected and fades with the medicine.
Along with hoarseness, some people notice a lump in the throat or a slightly heavy arm on the injected side. A warm, flushed feeling on that side of the face or hand is part of the nerve being blocked. These follow the same timeline as the droopy-eye sign and ease as the medicine wears off.
The neck can feel sore or tender where the needle went in, and mild bruising can appear over the next day or two. A cool pack and resting the neck usually help, and the clinic can tell you which pain medicines are safe for you. Pain that grows worse or swelling that keeps increasing is a reason to call your clinic.
At home, a hoarse voice or lump in the throat usually passes as numbness fades. Eat and drink carefully until swallowing feels normal. Call your clinic if hoarseness lasts past the next day, and seek urgent care for trouble breathing, chest pain, or symptoms that worsen.
Rare serious problems, such as bleeding or the medicine spreading to the wrong place, tend to show up during or soon after the injection, which is one reason you are watched in the clinic. Problems that persist or appear later deserve a call to your doctor and should not be assumed to be normal.