A 39-year-old man with a history of nerve inflammation developed recurrent bilateral brachial plexus neuritis — causing paralysis in both hands — after losing 70 pounds in eight months on semaglutide.
70 lbs in 8 monthsThe patient's rapid semaglutide-associated weight loss preceded recurrent bilateral brachial plexus neuritis with finger paralysis and persistent deficits
What the researchers found
The patient, a 39-year-old man with a prior episode of unilateral brachial neuritis, developed recurrent bilateral upper limb weakness following a 70-pound weight loss over 8 months on semaglutide. Specific deficits included bilateral radial sensory loss, finger extensor paralysis, right triceps weakness, and decreased left grip strength.
Corticosteroids provided pain relief but motor and sensory deficits persisted despite physiotherapy. This represents the first reported case linking semaglutide use with brachial plexus neuritis (Parsonage-Turner syndrome).
Why it matters
Semaglutide is used by millions of people for diabetes and weight loss. As its use expands, identifying rare but serious side effects is critical. This case suggests that rapid weight loss — whether caused by the drug directly or through nutritional deficiency — may trigger nerve damage in susceptible individuals. It's the first reported case linking semaglutide to brachial plexus neuritis.
How the study worked
This is a clinical case report documenting a single patient's experience. The diagnosis was based on clinical examination, patient history, and standard neurological assessment. The temporal association between semaglutide use, rapid weight loss, and symptom onset was noted.
What this study cannot tell us
This is a single case report, which is the weakest form of clinical evidence. It can establish a temporal association but cannot prove that semaglutide or the weight loss it caused directly triggered the nerve damage. The patient had a prior history of brachial neuritis, making him predisposed. The exact mechanism — whether related to the drug itself, rapid weight loss, nutritional deficiency, or coincidence — cannot be determined from one case.
How to read the evidence
This is a single case report — the lowest level of clinical evidence. It establishes a temporal association and raises a safety signal, but cannot prove causation. It is valuable as a 'first report' that may prompt larger surveillance studies.
When this study was published
Published in 2026, this case report reflects the very latest safety monitoring of semaglutide as its use continues to expand globally.
The bigger picture
As GLP-1 receptor agonists like semaglutide become some of the most prescribed drugs in the world, post-market surveillance for rare adverse events becomes increasingly important. This case adds to a growing collection of case reports documenting neurological complications potentially associated with GLP-1 drugs or the rapid weight loss they cause, though causation has not been established.
Questions still open
- Is the nerve damage caused by semaglutide itself, by rapid weight loss, by nutritional deficiency during weight loss, or by coincidence?
- Should patients with a history of brachial plexus neuritis be counseled about this risk before starting GLP-1 drugs?
- How common are neurological complications during rapid GLP-1-mediated weight loss, and should screening guidelines be developed?
Common questions
What is brachial plexus neuritis and how serious is it?
Should I be worried about nerve damage from semaglutide?
Read the original research
Recurrent bilateral brachial plexus neuritis following rapid semaglutide-induced weight loss: a case report.
BMC neurology, 26(1), 123
Citation
Lesinszki, Lukács S; Khalili, Radmanesh; Jiang, Haiyang; Jha, Shivangi; Bernad, Peter G. (2026). Recurrent bilateral brachial plexus neuritis following rapid semaglutide-induced weight loss: a case report.. BMC neurology, 26(1), 123. https://doi.org/10.1186/s12883-026-04664-4