Sympathomimetic Toxidrome
Jaw clenching is most commonly associated with the sympathomimetic toxidrome, particularly from stimulants like amphetamines, methamphetamine, and cocaine. 1, 2
Clinical Presentation
The sympathomimetic toxidrome presents with a constellation of findings that result from excessive adrenergic stimulation:
- Tachycardia and hypertension are hallmark cardiovascular signs 1, 2
- Agitation and hyperactivity reflect central nervous system stimulation 2
- Hyperthermia from increased metabolic activity and muscle activity 2
- Jaw clenching (bruxism) is a characteristic muscular manifestation, particularly prominent with methamphetamine abuse 3
- Mydriasis (dilated pupils) from sympathetic activation 2
Specific Agents Associated with Jaw Clenching
Methamphetamine deserves particular attention as it produces severe jaw clenching through its sympathomimetic effects. In a systematic study of 100 chronic methamphetamine abusers, 68% reported jaw clenching and 47% experienced temporomandibular joint pain, with clinical findings showing significantly more bruxism symptoms compared to controls 3. This chronic jaw clenching contributes to the devastating oral health effects seen in "meth mouth" 3.
Other sympathomimetic agents causing this toxidrome include amphetamines, cocaine, caffeine/theophylline, and withdrawal states from sedative-hypnotics 1.
Differential Considerations
While jaw clenching can occur in other contexts, it is not a feature of the other major toxidromes:
- Anticholinergic toxidrome presents with "hot as a hare, blind as a bat, dry as a bone, red as a beet, mad as a hatter" but not jaw clenching 2
- Cholinergic toxidrome causes excessive salivation, lacrimation, urination, and defecation (SLUDGE syndrome) without jaw clenching 2
- Opioid toxidrome produces CNS/respiratory depression, miosis, and bradycardia—the opposite of sympathomimetic effects 1, 2
One notable exception: suxamethonium-induced masseter spasm in malignant hyperthermia-susceptible patients causes exaggerated jaw rigidity, but this is a specific anesthetic complication rather than a toxidrome 1.
Management Priorities
Immediate stabilization takes precedence over toxidrome identification—prioritize airway, breathing, and circulation using standard BLS/ACLS protocols 4, 2.
For confirmed sympathomimetic toxicity:
- Benzodiazepines for agitation control and sedation 2
- Aggressive cooling measures for hyperthermia 2
- IV hydration to prevent rhabdomyolysis from excessive muscle activity 2
- Sodium bicarbonate for life-threatening dysrhythmias from cocaine or sodium channel blockade 2
Contact a regional poison center (1-800-222-1222) or medical toxicologist early to prevent deterioration 4, 2.