Can IV Acetaminophen Prevent Shivering After a Spinal?
Shivering after a spinal anesthetic is one of those problems that sounds minor until you are the patient. It is uncomfortable, it can be frightening, it raises oxygen demand, and it makes monitoring harder. We have several ways to treat it, but no agreed way to prevent it. A small trial from Thailand, published November 10, 2026 in Anesthesiology Research and Practice, tested a drug nearly every hospital already stocks: IV acetaminophen, known outside the United States as paracetamol.
The study
Ruenhunsa and colleagues at Khon Kaen University randomized 92 adults having surgery under spinal anesthesia. Half received IV acetaminophen 15 mg/kg over 15 minutes before the spinal, and half received the same volume of saline. Patients and assessors were blinded. The main outcome was whether the patient shivered at any point in the perioperative period.
In the per protocol analysis of 86 patients, shivering occurred in 26.2% of the acetaminophen group and 50.0% of the saline group. Shivering during surgery itself dropped from 22.7% to 4.8%. When it did happen, it was milder and shorter, and fewer patients needed rescue meperidine. Body temperature, rates of hypothermia, and nausea and vomiting were similar between groups.
How I read it
The direction of the result is encouraging, and the idea makes physiologic sense, since acetaminophen acts on central temperature regulation. I appreciate that the authors were candid about how fragile the finding is. Six patients dropped out after randomization. If you assume the worst about those six, the difference is no longer statistically significant, and the fragility index was 2, meaning that a change in outcome for just two patients would erase the result. That is not a reason to dismiss it, but it is a reason to call this a promising signal rather than an answer.
It is also worth noting what did not change. Core temperature was no different, so acetaminophen did not keep patients warmer. It seems to have changed the shivering response, not the heat loss behind it. Active warming and warm fluids still matter for the patient's temperature, whatever we give for comfort.
What it means for practice
Many of my patients in Casper having orthopedic, urologic, or cesarean surgery under a spinal already get scheduled acetaminophen as part of a multimodal pain plan. This trial suggests that giving that dose before the block, rather than later, might bring a second benefit at almost no added cost or risk. I would want a larger trial before calling it standard, and patients with liver disease or low body weight still need appropriate dosing. For now it is a reasonable, low risk adjustment worth discussing with your own team, alongside good warming.
Source
- Ruenhunsa T, Nonphiaraj S, Srikajonkiat D, et al. Intravenous paracetamol for perioperative shivering prophylaxis in patients undergoing spinal anesthesia: a prospective, randomized, double-blind controlled trial. Anesthesiology Research and Practice. 2026;2026:6133770. Published November 10, 2026. doi:10.1155/anrp/6133770. Article · PubMed
This post is clinician commentary for educational discussion. It is not medical advice for any reader's personal care. Anesthesia and perioperative decisions should be made with the treating clinician based on the individual patient's circumstances.