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Patient aftercare instructions

After a Stellate Ganglion Block: Side Effects, Recovery, and Signs It Worked

The hours and weeks after a stellate ganglion block, with how often each side effect happens, the one late warning sign to know, and what to expect by condition.

Questions? (646) 290-6660, 24/7

Modal Pain Management · Dr. Alex Movshis, MD

After a Stellate Ganglion Block: Side Effects, Recovery, and Signs It Worked

Questions or problems, any hour: (646) 290-6660. Emergency: call 911 or go to the nearest emergency room.

Full guide:
modalpain.com/aftercare/
stellate-ganglion-block/
Dr. Alex Movshis
Written and medically reviewed by Dr. Alex Movshis, MD Board-certified in pain medicine and anesthesiology · Last reviewed

At a glance

  1. Right after the block

    • A droopy eyelid, a smaller pupil, a red eye and a stuffy nose on the injected side are expected. They show the numbing medicine reached the nerves.
    • Your voice may be hoarse, your throat may feel like it has a lump in it, and your arm on that side may feel numb or heavy. These wear off with the numbing medicine.
    • We watch you for 30 to 60 minutes before you leave.

  2. Going home

    • Someone must take you home, or take a car service such as Uber or a taxi. Do not drive yourself or take the subway.
    • Do not drive until the droopy eyelid and any arm numbness have completely gone.
    • There are no food or drink restrictions. If your voice is hoarse, take small sips sitting up.

  3. The first 3 days

    • The eyelid, voice and arm return to normal as the numbing medicine wears off, which can take up to 24 hours. Still there after 24 hours? Call us.
    • Rarely, bleeding in the neck shows up hours or even days later. Growing neck swelling, trouble breathing or trouble swallowing your saliva means 911.
    • Restart any blood thinner on the plan we made with you before the block.

  4. The weeks after

    • Keep a simple daily note of the symptoms you came in for. That record, not how the block felt, tells us whether it worked.
    • For PTSD, the second treatment is usually 2 weeks after the first. Keep up your therapy and medicines in between.
    • Bring your notes to your follow-up visit.

Call 911 or go to the nearest emergency room for

  • Trouble breathing, noisy breathing, or a feeling that your throat is closing
  • Swelling in the neck that is growing, or new neck pain with swelling, in the hours or days after the block
  • A hoarse voice that comes back or gets worse after it had improved, or trouble swallowing your own saliva
  • A seizure, fainting, confusion, chest pain, or weakness or numbness in both arms or both legs
  • Thoughts of harming yourself. You can also call or text 988, the Suicide & Crisis Lifeline.

Call us at (646) 290-6660, day or night, for

  • A droopy eyelid, hoarse voice or arm numbness lasting more than 24 hours
  • Fever, redness, warmth or increasing pain at the injection site in the days after
  • Neck pain or stiffness with a fever, even weeks later
  • Feeling much more anxious or on edge than usual in the days after the block
  • Any question about your blood thinner plan

The eyelid on one side droops within minutes, and that is the sign we look for. It means the numbing medicine reached the nerves we aimed at, low in the front of the neck. The voice can go husky for a few hours and the arm can feel heavy. Most of what you feel today is expected, temporary and gone within a day. The one thing to keep in mind for the next few days is the neck itself.

These are the instructions Dr. Alex Movshis gives after a stellate ganglion block at Modal Pain Management. If yours was done elsewhere, the warning signs still apply, but follow your own physician’s instructions where they differ.

The first hours: what is expected

We block at the C6 level, low in the neck, with about 8 mL of 0.25% bupivacaine or 0.25% ropivacaine, under ultrasound with fluoroscopic confirmation. There is no steroid and no sedation. For PTSD we add a second level, C4, when your anatomy allows.

Horner’s syndrome. A droopy upper eyelid, a smaller pupil, a red eye and a stuffy nostril on the injected side. It starts within minutes. Under ultrasound, every block in one early study was working by 10 minutes (Kapral 1995). In a randomized trial of 4, 6 and 8 mL, 94% to 100% of patients had the droopy eyelid (Yoo 2019). With a dilute ropivacaine block it lasted about 2 to 3.5 hours (Jung 2011). Our blocks use more volume and long-acting medicine, so the eyelid can stay droopy for up to 24 hours.

Hoarseness and a lump in the throat. The numbing medicine can reach the nerve to the voice box. Hoarseness followed 3.9% of 809 ultrasound-guided blocks in one series, and trouble swallowing 3.4% (Aleanakian 2020). In the randomized trial, hoarseness followed 12% to 15% of blocks, with no real difference between the three volumes (Yoo 2019). After a bupivacaine block it cleared within 6 hours (Yang 2026).

A numb or heavy arm. The medicine can spread to the nerve roots nearby. It wears off with the block.

What the droopy eyelid does and does not tell you. It shows the medicine reached the sympathetic nerves. It does not tell you whether the block will help your symptoms. A warm hand is not a reliable sign either: the usual temperature target was met after only 38% to 55% of ultrasound-guided blocks (Yoo 2019, Kim 2025). Whether the block worked is judged case by case, by the symptoms you came in for.

Getting home, eating, and the rest of the day

We watch you for 30 to 60 minutes after the block, which is what the systematic review of complications recommends (Goel 2019). Someone must take you home, or take a car service such as Uber or a taxi. Do not drive yourself or take the subway. Your vision on the injected side is narrowed by the drooping eyelid, and the arm may be numb or weak. Do not drive until both have completely gone.

There are no food or drink restrictions. If your voice is hoarse or swallowing feels odd, take small sips sitting up until it settles.

Blood thinners. Tell us about every blood thinner before the block, including aspirin. We make the plan with you, and with the doctor who prescribed it when needed. Do not stop or change a blood thinner on your own. Restart it on the plan we made.

The late warning sign: swelling in the neck

This is rare, and it is the one thing worth knowing about after you leave. The block passes near small arteries in the neck, and very occasionally one bleeds into the space behind the throat. In a review of 27 published cases, symptoms began 2 hours or more after the block in 52%, and 78% needed emergency help with breathing (Higa 2006). Cases have appeared as late as 3 days after the block (Takanami 2009). Ultrasound may lower the risk: in a 12-patient comparison, a bleed showed up after 3 blocks done without imaging and after none done with ultrasound (Kapral 1995). It does not remove the risk.

Some hoarseness today is normal, so the warning sign is different: hoarseness that comes back or gets worse after it had improved, a neck that is swelling, trouble breathing, or trouble swallowing your own saliva. Any of these means 911.

Is it working? What to expect by condition

Pain from complex regional pain syndrome or other sympathetically maintained pain. The CRPS guidelines note there is no agreed definition of a successful sympathetic block, and that relief often outlasts the numbing medicine (Harden 2022). In a double-blind study, the relief 30 minutes after a block was similar to a saline injection, but relief after the real block lasted much longer, a mean of almost 4 days (Price 1998). So watch how long the relief lasts, not just how good the first hour feels. Relief after the first block predicted relief from a series better than the eyelid or hand temperature did (Aleanakian 2020). Use the time to push your physical therapy.

PTSD. We usually give two treatments 2 weeks apart. Some people notice a change within minutes to days (Kerzner 2021). In a series of 30 patients, PTSD scores fell within a week, with the biggest early changes in irritability, concentration and sleep (Lynch 2016). The randomized trial measured its result at 8 weeks, after two blocks two weeks apart (Rae Olmsted 2020). An earlier randomized trial found no difference from a sham injection (Hanling 2016), so not everyone responds. Adding the second level has not been shown to beat a single level in the one non-randomized comparison so far (Prasad 2023). Keep up your therapy and your medicines. In one report, two patients became much more anxious after a block on the left side, which settled after a right-sided block (Mulvaney 2025). If you feel much more anxious than usual, call us. If you have thoughts of harming yourself, call 911 or call or text 988, the Suicide & Crisis Lifeline.

Long COVID. In one practice’s review of 41 patients, most noticed a change within 15 minutes, and fatigue and brain fog improved over one to two weeks or within a day (Pearson 2023). In a small pilot, sleep and pain changed by the first week, and dizziness on standing only by the fourth (Wang 2025). Neither study had a placebo group. The only randomized trial, for a distorted sense of smell after COVID, found the block no better than a saltwater injection (Farrell 2025).

Hot flashes. In a small study of breast cancer survivors, hot flashes fell in the first 2 weeks and kept falling over 12 (Lipov 2008). In the placebo-controlled trial, the advantage on moderate to severe hot flashes was clearest at months 4 to 6 (Walega 2014). Keep counting for several months.

When to go to the emergency room

Serious problems are uncommon. In a 1992 survey of about 45,000 blocks, from before image guidance was common, severe complications occurred in 1.7 per 1,000 (Wulf 1992). In a randomized PTSD trial of 113 people, 74 of whom had ultrasound-guided blocks, no serious adverse events were reported in either group (Rae Olmsted 2020). The systematic review of published complications found that most happened during the injection or shortly after, while patients were still being watched, but that bleeding and infection can show up late (Goel 2019). Trouble breathing, a neck that is swelling, hoarseness that comes back or gets worse, trouble swallowing your saliva, a seizure, fainting or chest pain are emergencies. Call 911 or go to the nearest emergency room, and tell the team you had a stellate ganglion block and on what date.

After the result

Dr. Movshis goes over your symptom notes with you. A clear response that lasts means the block can be repeated or the series continued. Relief that matches the numbing medicine and then fades, or no change at all, means we look again. For pain, that often means looking for a different source. For PTSD, long COVID or hot flashes, it may simply mean the block is not for you. The routes below are where we usually look next. The stellate ganglion block page explains who the block is for, what insurance covers and what the off-label uses cost.

If the stellate ganglion block did not help: what that usually means

A well-placed block that changes nothing is useful information. For pain, it suggests the sympathetic nerves are not what keeps the pain going. For PTSD, long COVID or hot flashes, the evidence says some people simply do not respond. These are the patterns we look at next, including for patients whose block was done elsewhere. Bring the procedure note and your symptom notes.

Burning arm or hand pain with swelling, color or temperature change, after an injury or surgery

Usually: Complex regional pain syndrome

At Modal Pain: A short series of blocks only if the first one helped, alongside physical therapy

Neck pain with pain, numbness or tingling running down the arm in one strip

Usually: A pinched nerve root in the neck

At Modal Pain: Cervical epidural injection

Burning or electric pain in a band where shingles was, months later

Usually: Postherpetic neuralgia

At Modal Pain: Nerve blocks at the affected nerves, with medicine adjusted

Headache on 15 or more days a month, with migraine features on at least 8 of them, for more than 3 months

Usually: Chronic migraine

At Modal Pain: Botox for chronic migraine, alongside preventive medicines

Modal Pain Management accepts most commercial PPO plans, including Aetna, Anthem Blue Cross Blue Shield, Cigna, Empire Blue Cross Blue Shield, the Empire Plan, Oscar, Oxford, UMR and UnitedHealthcare, and does not accept Medicare, Medicaid, HMO plans, or workers' compensation. Off-label stellate ganglion blocks are self-pay, and our prices are published. Insurance details · Self-pay pricing

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369 Lexington Ave, Floor 25, New York, NY 10017 · same-week appointments are routinely available · in-suite ultrasound and fluoroscopy.

Frequently asked questions

The expected ones are on the injected side: a droopy eyelid, a smaller pupil, a red eye and a stuffy nose, together called Horner's syndrome. In a randomized trial of ultrasound-guided blocks, 94% to 100% of patients had the droopy eyelid (Yoo 2019). A hoarse voice follows in roughly 4 to 15 of every 100 blocks, and trouble swallowing in about 3 to 6 (Yoo 2019, Aleanakian 2020). The arm on that side can feel numb or heavy. All of these wear off with the numbing medicine.

Serious problems are uncommon. In a 1992 survey of about 45,000 blocks, from before image guidance was common, severe complications occurred in 1.7 per 1,000 (Wulf 1992). In a randomized PTSD trial of 113 people, 74 of whom had ultrasound-guided blocks, no serious adverse events were reported in either group (Rae Olmsted 2020). The rare emergencies are a seizure during the injection, which happens while you are being monitored, and bleeding in the neck, which can show up hours or days later (Goel 2019, Higa 2006, Takanami 2009). That late bleeding is why we ask you to know the warning signs.

Usually several hours, and up to 24 hours, because bupivacaine and ropivacaine are long-acting. With a dilute ropivacaine block, the droopy eyelid lasted about 2 to 3.5 hours (Jung 2011). In one study, the two patients who became hoarse after about 2 mL of bupivacaine were back to normal within 6 hours (Yang 2026). Our blocks use about 8 mL, so expect the effects to last longer. A droopy eyelid, hoarse voice or arm numbness lasting more than 24 hours needs a call.

The droopy eyelid shows the numbing medicine reached the sympathetic nerves. It does not show whether the block will help. A warm hand is not a reliable sign either: the usual temperature target was met after only 38% to 55% of ultrasound-guided blocks (Yoo 2019, Kim 2025). Whether the block worked is judged case by case, by what happens to the symptoms you came in for over the following days and weeks.

No, not to get home. Someone must take you, or take a car service such as Uber or a taxi. Do not take the subway. The droopy eyelid narrows your vision on that side and the arm can be numb or weak for hours. Wait until both have completely gone before you drive.

Yes, there are no food or drink restrictions. The numbing medicine can briefly affect the nerve to the voice box, which is why some people are hoarse. If your voice is hoarse or swallowing feels odd, take small sips sitting up until it settles. Trouble swallowing your own saliva is an emergency.

Some people notice a change within minutes to days (Kerzner 2021). In a series of 30 patients, PTSD scores fell within a week, with the biggest early changes in irritability, concentration and sleep (Lynch 2016). The randomized trial measured the result at 8 weeks, after two blocks two weeks apart (Rae Olmsted 2020). An earlier randomized trial found no difference from a sham injection (Hanling 2016), so not everyone responds.

References

Every figure on this page comes from the sources below. Where no study exists, the page says so and explains the reasoning instead.

  1. Goel V, Patwardhan AM, Ibrahim M, et al. Complications associated with stellate ganglion nerve block: a systematic review. Reg Anesth Pain Med. 2019. doi:10.1136/rapm-2018-100127 · PubMed
  2. Wulf H, Maier C. Complications and side effects of stellate ganglion blockade. Results of a questionnaire survey. Anaesthesist. 1992. · PubMed
  3. Kerzner J, Liu H, Demchenko I, et al. Stellate ganglion block for psychiatric disorders: a systematic review of the clinical research landscape. Chronic Stress. 2021. doi:10.1177/24705470211055176 · PubMed
  4. Higa K, Hirata K, Hirota K, et al. Retropharyngeal hematoma after stellate ganglion block: analysis of 27 patients reported in the literature. Anesthesiology. 2006. doi:10.1097/00000542-200612000-00024 · PubMed
  5. Takanami I, Abiko T, Koizumi S. Life-threatening airway obstruction due to retropharyngeal and cervicomediastinal hematomas following stellate ganglion block. Thorac Cardiovasc Surg. 2009. doi:10.1055/s-2008-1038845 · PubMed
  6. Yoo Y, Lee CS, Kim YC, et al. A randomized comparison between 4, 6 and 8 mL of local anesthetic for ultrasound-guided stellate ganglion block. J Clin Med. 2019. doi:10.3390/jcm8091314 · PubMed
  7. Jung G, Kim BS, Shin KB, et al. The optimal volume of 0.2% ropivacaine required for an ultrasound-guided stellate ganglion block. Korean J Anesthesiol. 2011. doi:10.4097/kjae.2011.60.3.179 · PubMed
  8. Aleanakian R, Chung BY, Feldmann RE Jr, et al. Effectiveness, safety, and predictive potential in ultrasound-guided stellate ganglion blockades for the treatment of sympathetically maintained pain. Pain Pract. 2020. doi:10.1111/papr.12892 · PubMed
  9. Yang L, Liu J, Yang Y, et al. Determination of the ED90 and ED99 of liposomal versus conventional bupivacaine for ultrasound-guided stellate ganglion block: a biased-coin design study. Drug Des Devel Ther. 2026. doi:10.2147/DDDT.S609398 · PubMed
  10. Kim J, Cha J, Choi SN, et al. Multicenter prospective randomized comparison of ultrasound-guided stellate ganglion versus thoracic paravertebral block for sympathetic blockade in chronic upper extremity pain. Anesth Analg. 2025. doi:10.1213/ANE.0000000000007014 · PubMed
  11. Kapral S, Krafft P, Gosch M, et al. Ultrasound imaging for stellate ganglion block: direct visualization of puncture site and local anesthetic spread. A pilot study. Reg Anesth. 1995. · PubMed
  12. Rae Olmsted KL, Bartoszek M, Mulvaney S, et al. Effect of stellate ganglion block treatment on posttraumatic stress disorder symptoms: a randomized clinical trial. JAMA Psychiatry. 2020. doi:10.1001/jamapsychiatry.2019.3474 · PubMed
  13. Hanling SR, Hickey A, Lesnik I, et al. Stellate ganglion block for the treatment of posttraumatic stress disorder: a randomized, double-blind, controlled trial. Reg Anesth Pain Med. 2016. doi:10.1097/AAP.0000000000000402 · PubMed
  14. Lynch JH, Mulvaney SW, Kim EH, et al. Effect of stellate ganglion block on specific symptom clusters for treatment of post-traumatic stress disorder. Mil Med. 2016. doi:10.7205/MILMED-D-15-00518 · PubMed
  15. Prasad S, Jain N, Umar TP, et al. Sympathetic nerve blocks for posttraumatic stress disorder: an evidentiary review for future clinical trials. Front Psychiatry. 2023. doi:10.3389/fpsyt.2023.1309986 · PubMed
  16. Mulvaney SW, Lynch JH, Means GE, et al. Reversible increased anxiety following left-sided stellate ganglion block to treat posttraumatic stress disorder: a case report. Mil Med. 2025. doi:10.1093/milmed/usae338 · PubMed
  17. Pearson L, Maina A, Compratt T, et al. Stellate ganglion block relieves long COVID-19 symptoms in 86% of patients: a retrospective cohort study. Cureus. 2023. doi:10.7759/cureus.45161 · PubMed
  18. Wang S, Salway RJ, Nicklay M, et al. Effectiveness of dual sympathetic blocks for sympathetically mediated symptoms in post-acute sequelae of SARS-CoV-2 (PASC): an open-label, non-randomized pilot study. Cureus. 2025. doi:10.7759/cureus.81530 · PubMed
  19. Farrell NF, Crock LW, Islam A, et al. Stellate ganglion block for the treatment of COVID-19-induced parosmia: a randomized clinical trial. JAMA Otolaryngol Head Neck Surg. 2025. doi:10.1001/jamaoto.2025.1304 · PubMed
  20. Harden RN, McCabe CS, Goebel A, et al. Complex regional pain syndrome: practical diagnostic and treatment guidelines, 5th edition. Pain Med. 2022. doi:10.1093/pm/pnac046 · PubMed
  21. Price DD, Long S, Wilsey B, et al. Analysis of peak magnitude and duration of analgesia produced by local anesthetics injected into sympathetic ganglia of complex regional pain syndrome patients. Clin J Pain. 1998. doi:10.1097/00002508-199809000-00008 · PubMed
  22. Walega DR, Rubin LH, Banuvar S, et al. Effects of stellate ganglion block on vasomotor symptoms: findings from a randomized controlled clinical trial in postmenopausal women. Menopause. 2014. doi:10.1097/GME.0000000000000194 · PubMed
  23. Lipov EG, Joshi JR, Sanders S, et al. Effects of stellate-ganglion block on hot flushes and night awakenings in survivors of breast cancer: a pilot study. Lancet Oncol. 2008. doi:10.1016/S1470-2045(08)70131-1 · PubMed

These are general instructions after a stellate ganglion block (sgb). If the instructions you were given at discharge differ, follow the ones you were given, because they account for your medications and your procedure. For anything you are unsure about, call (646) 290-6660. See the stellate ganglion block (sgb) page for how the procedure works and who it helps, or the aftercare instructions for other procedures.

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