This article documents the clinical management protocol for grayanotoxin (GTX) poisoning from mad honey consumption, as established in the peer-reviewed literature, primarily Ullah et al. (2018), Jansen et al. (2012), and the case series synthesised by Salici and Atayoglu (2015). It is a reference document for emergency medicine clinicians, internal medicine physicians, cardiologists, and medical educators.
This article is distinct from the CMHI Emergency Response guide (consumer-facing) and the Ullah et al. (2018) paper summary. It organises the clinical information as a stepwise protocol with the mechanism explanation for each intervention, the escalation criteria, and the evidence basis for each recommendation.
Diagnosis: No Laboratory Testing Required
Mad honey poisoning can be diagnosed on clinical history and physical examination alone, without laboratory confirmation. Ullah et al. (2018) established this explicitly: the combination of bradycardia, hypotension, and dizziness following honey consumption is sufficient to initiate treatment without waiting for toxicological confirmation.
Clinical triad
Bradycardia (heart rate below 60 bpm, typically 40 to 50 bpm in moderate presentations), hypotension (systolic blood pressure below 90 mmHg in moderate to severe presentations), and dizziness with or without secondary neurological symptoms. All three components arising together following honey consumption provide a high-confidence differential diagnosis.
Consumption history
Ask directly: what honey was consumed, how much, and when. In endemic regions (Turkey’s Black Sea coast, Nepal’s highland districts), the differential is immediately clear. In non-endemic settings, Europe, North America, and East Asia, mad honey poisoning may not be the first diagnosis considered. In any patient with unexplained bradycardia and hypotension, dietary history, including honey consumption, should be included in the acute assessment.
ECG: the primary monitoring tool
Obtain an ECG immediately. It establishes the severity of conduction impairment, guides treatment escalation, and provides the baseline for monitoring response. ECG findings in order of severity: sinus bradycardia, first-degree AV block (PR greater than 200 ms), second-degree AV block (Wenckebach / Mobitz I), complete (third-degree) AV block, atrial fibrillation, ventricular escape rhythm. The ECG finding drives the escalation decision.
Severity Stratification
- Mild: HR 50 to 60 bpm, SBP above 90 mmHg, ambulatory, sinus bradycardia on ECG without block. Management: IV access, monitoring, IV saline may be sufficient.
- Moderate: HR 40 to 50 bpm, SBP 70 to 90 mmHg, pronounced symptoms, first or second degree AV block on ECG. Management: IV saline plus atropine required.
- Severe: HR below 40 bpm, SBP below 70 mmHg or unrecordable, complete AV block or haemodynamically compromising arrhythmia, syncope or altered consciousness. Management: full escalation protocol.
The Four-Step Treatment Protocol
| Step | Intervention | Indication | Dose / Details | Mechanism |
| 1 | IV fluid resuscitation | All presentations with hypotension (SBP below 90 mmHg) | Normal saline or Lactated Ringer’s; 500 mL bolus titrated to response | Restores preload; counteracts GTX-induced peripheral vasodilation; addresses the vascular component of hypotension |
| 2 | Atropine sulphate IV | Bradycardia below 50 bpm or any degree of AV block | 0.5 to 3 mg IV; start at 0.5-1.0 mg; repeat every 3-5 min to max 3 mg | Competitive M2 muscarinic receptor antagonist; blocks vagal overstimulation; restores SA node automaticity and AV conduction |
| 3 | Catecholamine support | Persistent haemodynamic compromise after adequate fluids and atropine | Noradrenaline 0.1-0.3 mcg/kg/min IV; adrenaline if severe persistent bradycardia | Beta-1 chronotropic effect; alpha-1 vasoconstriction supplements atropine where vagal blockade alone is insufficient |
| 4 | Temporary transvenous pacemaker | Complete AV block unresponsive to atropine; ventricular escape with haemodynamic compromise | Rate 60-80 bpm; maintain until spontaneous AV conduction resumes as GTX clears (6-24h); then wean and remove | Bridges complete conduction failure; GTX cleared by normal metabolism; pacemaker is temporary by design |
Step 1: IV Fluid Resuscitation
IV fluid resuscitation addresses hypotension by restoring circulating volume and peripheral vascular filling pressure. GTX produces hypotension through two simultaneous mechanisms: reduced cardiac output from bradycardia, and peripheral vasodilation from impaired sympathetic vasoconstrictor tone. Saline addresses the vascular filling component but not the cardiac rate component, which is why atropine is required alongside rather than instead of it.
Normal saline (0.9% NaCl) or Lactated Ringers are both appropriate. A 500 mL bolus titrated to haemodynamic response is a reasonable starting point. In elderly patients with pre-existing cardiac conditions, volume loading should be titrated carefully.
Step 2: Atropine Sulphate, Mechanism, Dosing, and Response
Why atropine works specifically for GTX poisoning
GTX amplifies vagal tone through two compounding mechanisms: sustained VGSC depolarisation in autonomic neurons increases acetylcholine release at cardiac nerve terminals, and direct VGSC disruption in nodal cells impairs intrinsic pacemaker and conduction function. Atropine is a competitive antagonist at M2 muscarinic receptors at the SA and AV nodes. By blocking M2, atropine counteracts the vagal amplification regardless of acetylcholine release levels.
Atropine’s efficacy in most GTX poisoning cases pharmacologically confirms that vagally-mediated bradycardia is the dominant mechanism in typical presentations. The SA node’s pacemaker function is suppressed rather than damaged; it recovers as GTX clears.
Dosing and response
Ullah et al. (2018) document atropine doses of 0.5 to 3 mg IV across the case record. Start at 0.5 to 1.0 mg IV and repeat every 3 to 5 minutes if heart rate response is inadequate. The maximum total dose is typically 3 mg in adults. Heart rate normalisation in atropine-responsive cases typically occurs within minutes of IV administration.
When atropine is insufficient
Cases where atropine provides only partial reversal involve elderly patients, those with pre-existing conduction abnormalities, or very high GTX exposure. The residual impairment reflects direct VGSC disruption in nodal tissue that is not mediated by muscarinic receptors and cannot be addressed by muscarinic blockade alone. This is the mechanistic explanation from Jansen et al. (2012) for why escalation beyond atropine is necessary in some cases.
Step 3: Catecholamine Support
Catecholamine support is indicated when haemodynamic compromise continues after adequate fluids and atropine. Noradrenaline at 0.1 to 0.3 micrograms per kg per minute IV addresses both components of GTX haemodynamic compromise: its beta-1 receptor effect provides chronotropic support, and its alpha-1 vasoconstrictor effect counters peripheral vasodilation that atropine does not directly address.
Catecholamine support is a bridging measure while GTX clears. Titrate to maintain adequate haemodynamic parameters and wean as the patient improves.
Step 4: Temporary Transvenous Pacemaker
Temporary pacemaker insertion is reserved for complete (third-degree) AV block unresponsive to pharmacological management. When AV conduction has completely failed, a ventricular escape rhythm at 20 to 40 bpm provides inadequate cardiac output. A temporary pacemaker at 60 to 80 bpm restores adequate output while GTX clears.
The temporary designation is pharmacologically justified: GTX produces a reversible pharmacological blockade, not structural myocardial damage. As GTX is metabolised and eliminated, typically within 6 to 24 hours, AV conduction resumes spontaneously. The pacemaker is removed once the patient demonstrates an adequate spontaneous rhythm. A permanent pacemaker is not indicated for GTX poisoning.
ECG Monitoring: Findings and Actions
| ECG Finding | Severity | Action | Notes |
| Sinus bradycardia | Mild to moderate | HR below 50: give atropine. HR 50-60: monitor and IV saline. | Most common finding. Present in almost all GTX poisoning cases. |
| First-degree AV block (PR >200 ms) | Moderate | Give atropine if not given. Monitor for progression. | Confirms AV nodal involvement. Atropine typically sufficient. |
| Second-degree AV block (Wenckebach) | Moderate to severe | Atropine; titrate dose; prepare pacemaker if response is inadequate. | Progressive PR prolongation with dropped beats. |
| Complete (third-degree) AV block | Severe | Atropine plus catecholamine. Temporary pacemaker if no atropine response. | Complete conduction failure. Ventricular escape at 20-40 bpm. Haemodynamically compromising. |
| Atrial fibrillation | Moderate to severe | Rate control and haemodynamic support. Titrate atropine carefully, as it may accelerate the ventricular rate in AF. | Less common than AV block. Rate management is a priority. |
| Ventricular escape rhythm | Severe | Pacemaker insertion indicated. | Result of complete AV block. 20-40 bpm. Inadequate output. |
Special Populations
Elderly patients have reduced cardiovascular reserve and age-related conduction slowing as baseline. GTX-induced impairment is superimposed, producing more severe presentations at comparable exposures. Anticholinergic atropine side effects are more pronounced; monitor for confusion and urinary retention.
Beta-blocker users present with combined bradycardia from two independent mechanisms: GTX vagal amplification and beta-1 blockade. Atropine addresses the vagal component; the beta-blocker effect remains. In severe persistent cases, glucagon may be considered extrapolated from beta-blocker overdose management, though this specific combination in GTX poisoning is not formally studied.
Pre-existing cardiac conditions, sick sinus syndrome, existing AV block, and documented arrhythmia are high-risk. A low threshold for early atropine and early pacemaker preparation is appropriate.
What Not to Do
| Management approaches that are harmful or inappropriate in GTX poisoning Calcium channel blockers as rate control for AF: these reduce AV conduction independently of GTX and can produce complete AV block. Contraindicated as rate-control agents in GTX-associated atrial fibrillation. Digibind or digoxin-specific antibody fragments: GTX is a Site 2 sodium channel toxin, not a cardiac glycoside. Digibind has no role. Misattributing GTX-related ST changes to acute coronary syndrome: antiplatelet or thrombolytic therapy based on GTX-related ST changes is inappropriate. GTX poisoning precedes ACS as the working diagnosis when a honey consumption history is present. Delaying atropine for complete AV block: clinical diagnosis can be made on history and physical examination alone. Laboratory confirmation is not required before initiating treatment. Aggressive atropinisation without monitoring: atropine near the 3 mg maximum can produce significant tachycardia as GTX clears. Monitor heart rate throughout. |
Discharge Criteria and Observation Period
Observation in the case record ranges from 6 to 72 hours, depending on initial severity. Mild cases responding to saline may be discharged after 6 to 12 hours with documented normal sinus rhythm. Moderate cases typically require 12 to 24 hours. Severe cases requiring pacemaker insertion require ICU-level observation until the pacemaker is successfully weaned.
Discharge criteria: spontaneous HR above 60 bpm without atropine or pacemaker support; blood pressure adequate without vasopressor; no ongoing conduction impairment on ECG; patient ambulatory; tolerating oral intake. No anti-arrhythmic prophylaxis is required; GTX is a reversible pharmacological effect.
Evidence Base and Limitations
The protocol derives from retrospective clinical case series rather than randomised controlled trials. No RCT has evaluated any component. The dose ranges and escalation hierarchy are supported by convergent findings across hundreds of cases in the Turkish and Nepalese records. The absence of RCT evidence does not undermine the protocol’s utility: GTX has a well-characterised mechanism, and the treatment choices follow logically from it.
What We Don’t Know Yet
Optimal atropine dosing has not been established by a controlled trial. The 0.5 to 3 mg range reflects what was used in documented cases, not what has been pharmacologically optimised. The role of catecholamines in GTX poisoning has not been formally evaluated; use is extrapolated from general emergency medicine principles. Optimal monitoring duration has not been established by evidence-based criteria.
Summary Protocol Reference
Diagnose based on history plus triad. ECG immediately. No laboratory testing required to initiate treatment.
Mild (HR above 50, sinus bradycardia): IV saline plus monitoring. Moderate (HR 40-50, AV block): IV saline plus atropine 0.5-1 mg IV. Severe (HR below 40, complete AV block, compromise): IV saline, atropine to 3 mg, catecholamine support, prepare pacemaker.
Temporary pacemaker for a complete AV block unresponsive to atropine. Wean when spontaneous conduction resumes. Observe 6+ hours mild, 12-24h moderate, ICU for severe. Discharge when spontaneous HR above 60 bpm, adequate BP without support, and no conduction impairment.
