Topical Magnesium Sulfate Versus Peritonsillar Bupivacaine for Post-Tonsillectomy Pain Relief in Children

Tonsillectomy (tonsil removal) is a very common surgery for children, but it often causes significant throat and ear pain afterward. Doctors usually inject a numbing medicine, such as bupivacaine, into the area around the tonsils to help control this pain. However, these injections require needles, which can cause swelling, distort tissue, and slightly increase the risk of bleeding or infection, and the pain relief typically only lasts for about 4 to 6 hours.

This study is investigating a needle-free alternative to see if it provides effective pain relief. The researchers are testing a medication called magnesium sulfate, which blocks certain pain receptors and can be applied directly to the surgical site using a soaked gauze pad instead of a needle injection.

The main goal of this clinical trial is to compare how well topical magnesium sulfate relieves pain compared to standard bupivacaine injections in children undergoing tonsillectomy.

The study will include 40 children between the ages of 8 and 15 years old. During the surgery, while under general anesthesia, half of the children will receive the topical magnesium sulfate pad applied to the surgical area for 5 minutes, and the other half will receive the standard bupivacaine injection. After the surgery, researchers will measure the children's pain levels using visual pain scales featuring faces and numbers. They will also track how much extra pain medication the children need, how well their surgical wounds heal, and if they experience any adverse effects.

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Key information

Conditions

Post-tonsillectomy Pain Agnosia Nervous System Diseases Neurobehavioral Manifestations Neurologic Manifestations Odynophagia Pain Pain, Postoperative Pathologic Processes Pathological Conditions, Signs and Symptoms Perceptual Disorders Postoperative Complications Postoperative Pain Signs and Symptoms Tonsillectomy Tonsillectomy Distress Syndrome

Age range

8 year–15 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 4

About this study

Postoperative pain following tonsillectomy is a primary cause of morbidity in the pediatric population, frequently leading to "tonsillectomy distress syndrome," which is characterized by severe odynophagia, referred otalgia, and psychological distress. The underlying pathophysiology of this pain is complex, involving both mechanical trauma to the pharyngeal constrictor muscles and the chemical irritation of the vagus and glossopharyngeal nerve endings.

While perioperative analgesia is traditionally managed with local anesthetic infiltration, such as bupivacaine, its analgesic efficacy is typically limited to a short duration of 4 to 6 hours. Furthermore, the physical act of needle infiltration can induce tissue edema, distort surgical planes, and potentially elevate the risk of postoperative complications, including infection and hemorrhage.

Recent advancements in pain management have highlighted the role of N-methyl-D-aspartate (NMDA) receptors in peripheral tissues, presenting new avenues for non-invasive analgesia. Magnesium sulfate serves as an NMDA receptor antagonist by blocking its calcium channel in a voltage-dependent manner. This trial investigates whether applying magnesium sulfate topically to the tonsillar fossa can provide effective postoperative analgesia without the inherent risks associated with needle infiltration.

To ensure procedural standardization across the study, all tonsillectomies in this prospective, randomized trial will be performed utilizing a cold dissection technique under general anesthesia. Postoperatively, patients will be systematically evaluated to assess pain intensity, mucosal healing via a 5-point fibrin and epithelialization grading scale, and the overall requirement for rescue analgesics.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

Pediatric patients aged 8-15 years undergoing elective tonsillectomy.

Exclusion criteria

Patients younger than 8 years or older than 15 years.
Known allergy to magnesium sulfate or bupivacaine.
Pre-existing neurological disorders (for example, neuromuscular diseases, epilepsy) that could affect pain perception or magnesium metabolism.
Pre-existing cognitive impairment or developmental delay affecting pain assessment.
Chronic pain syndromes or regular use of analgesics.
Coagulopathy or bleeding disorders.

Treatment and study plan

Magnesium sulfate

Drug

Topical application via a sterile gauze soaked in 5 mL of 20% magnesium sulfate (2mg/kg) packed into the fossa for 5 minutes post-hemostasis.

Bupivacaine

Drug

Peritonsillar infiltration involving the injection of 2 mL of 0.25% bupivacaine into the superior, middle, and inferior poles of the peritonsillar space.

Primary outcomes

Postoperative Pain Intensity Assessed by the Wong-Baker FACES Pain Rating Scale

Time frame: At 24 hours postoperatively

The Wong-Baker FACES Pain Rating Scale is a visual assessment tool that features a series of six cartoon faces showing different emotional expressions to help pediatric patients communicate their pain levels. The scale ranges from a minimum score of 0, which corresponds to a happy, smiling face meaning "No Hurt," to a maximum score of 10, which corresponds to a sad, crying face meaning "Hurts Worst". Higher scores on this scale indicate greater pain intensity, reflecting a worse patient outcome.

Sponsors and collaborators

Lead sponsor

Assiut University

Other

Registry information

Official study title

Topical Magnesium Sulfate Versus Peritonsillar Bupivacaine Infiltration for Post-Tonsillectomy Analgesia: A Prospective, Randomized Trial

Important dates

Study start: 2026
Primary completion: 2027
Study completion: 2027
First posted: Aug 12, 2026
Registry last updated: Aug 12, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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