Buprenorphine Does Not Cause Lock Jaw (Trismus)
Buprenorphine is not associated with trismus (lock jaw) based on available clinical evidence and guidelines. The provided guidelines and research do not identify trismus as a recognized adverse effect of buprenorphine in patients with substance use disorder or chronic pain 1.
Known Adverse Effects of Buprenorphine
The documented side effects of buprenorphine include 2:
- Headache, dizziness, and somnolence
- Constipation, dry mouth, nausea, and vomiting
- Pruritus and erythema (particularly at application sites for transdermal formulations)
- Respiratory depression (with a ceiling effect, making it safer than full opioid agonists) 1, 3
Recent FDA safety communications have highlighted xerostomia (dry mouth) and dental caries associated with sublingual and buccal formulations of buprenorphine 4. However, trismus is not mentioned in these warnings.
Important Distinction: Trismus from Other Medications
While trismus is not associated with buprenorphine, it has been reported with other psychotropic medications:
- Bupropion (not buprenorphine) has been documented to cause acute dystonia presenting as trismus, neck stiffness, and TMJ subluxation 5
- Duloxetine has been reported to cause isolated trismus as a manifestation of acute dystonia 6
Clinical Pitfall to Avoid
Do not confuse bupropion (an antidepressant) with buprenorphine (an opioid partial agonist). The similar names can lead to medication errors, but their side effect profiles are entirely different 5.
Formulation-Specific Considerations
Different buprenorphine formulations have distinct safety profiles 1, 7:
- Sublingual tablets/films: Approved for opioid use disorder; associated with dental issues due to local acidic effects 4
- Transdermal patches: Approved for chronic pain; bypass first-pass hepatic metabolism and may provide superior analgesia with fewer systemic side effects 1, 3
- Neither formulation is associated with trismus or jaw dysfunction
Clinical Recommendation
If a patient on buprenorphine develops trismus, investigate alternative causes 5, 6:
- Review all medications for agents known to cause dystonic reactions (antipsychotics, bupropion, duloxetine, metoclopramide)
- Assess for dental/TMJ pathology unrelated to medication
- Consider neurological causes of jaw dysfunction
- Do not discontinue buprenorphine based on concern for trismus, as this is not a recognized adverse effect and discontinuation may precipitate withdrawal or loss of OUD treatment efficacy 1, 7