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Updated: Mar 12, 2026
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Assessment of Morphine-induced Hyperalgesia and Analgesic Tolerance in Mice Using Thermal and Mechanical Nociceptive Modalities
Published on: July 29, 2014
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Morphine-induced hearing loss.
Leire Leache1, Irene Aquerreta2, Libe Moraza1
1Pharmacy Services, Clínica Universidad de Navarra, Pamplona, Spain.
Summary
Oral morphine may cause severe hearing loss and tinnitus. This case report details a patient who developed these symptoms after high-dose oral morphine, requiring hearing aids even after discontinuation.
Area of Science:
- Otolaryngology
- Pharmacology
- Clinical Toxicology
Background:
- Opioid analgesics, such as oral morphine, are widely prescribed for pain management.
- Sensorineural hearing loss and tinnitus are potential, though rarely reported, adverse effects of certain medications.
Observation:
- A 52-year-old male patient experienced sudden bilateral sensorineural hearing loss and tinnitus.
- These auditory symptoms emerged after the initiation of high-dose oral morphine (up to 120 mg daily).
- Extensive investigations ruled out other common causes of hearing loss, including other medications and neurological conditions.
Findings:
- The patient's hearing loss was temporally associated with oral morphine use.
- The adverse drug reaction probability scale classified the event as 'probable' morphine-induced ototoxicity.
- Hearing loss persisted and required hearing aid use even after the discontinuation of oral morphine.
Implications:
- This case highlights the potential ototoxicity of oral morphine, emphasizing the need for vigilance in patients experiencing auditory changes during opioid therapy.
- Further research is warranted to elucidate the mechanisms of opioid-induced ototoxicity and establish clear diagnostic criteria.
- Clinicians should consider morphine-induced ototoxicity in the differential diagnosis of sudden hearing loss and tinnitus, particularly in patients on high-dose or long-term opioid treatment.
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