Why this drug is interesting
Ethanol is the only drug on this site whose antidotal action is the same thing people use it for recreationally. Alcohol dehydrogenase has a far higher affinity for ethanol than for methanol or ethylene glycol, so an ethanol infusion occupies the enzyme and the toxic alcohol is excreted unchanged rather than converted to formate or to glycolate and oxalate. Saturate the enzyme with something harmless and the poison stops being one.
It is also the antidote that best illustrates why a better molecule wins. Everything wrong with ethanol is practical: it sedates a patient you need to assess, the dose depends on how much they normally drink, and it has to be titrated to a blood level that most laboratories will not run quickly out of hours.
Pharmacology
Mechanism
Methanol and ethylene glycol are relatively benign until alcohol dehydrogenase gets to them. Methanol becomes formaldehyde and then formate, which poisons the optic nerve and drives a severe metabolic acidosis. Ethylene glycol becomes glycoaldehyde, then glycolate and oxalate, producing acidosis and calcium oxalate crystal nephropathy.
Ethanol competes for the same enzyme with substantially greater affinity. Maintained at an adequate blood concentration, it prevents the toxic metabolites forming at all, buying time for renal excretion or dialysis to remove the parent alcohol.
Why the dose depends on drinking history
Chronic alcohol consumption induces ethanol metabolism, so a regular drinker clears an ethanol infusion considerably faster than a non-drinker and needs a higher rate to hold the same blood level. This is one of the very few drugs whose maintenance dose is stratified by social history — the UK label tabulates three separate rates for non-drinker/child, average adult and drinker.1
Dosing
Loading dose
600–800 mg/kg, given parenterally as 7.5 mL/kg of a 10% infusion of ethanol in 5% glucose, over 30 minutes, preferably via a central venous catheter.1
Maintenance and dialysis
| Regimen | Absolute (100%) ethanol | Volume of 5% | Volume of 10% |
|---|---|---|---|
| Loading dose, over 30 min | 600–800 mg/kg | 15 mL/kg | 7.5 mL/kg |
| Maintenance — non-drinker or child | 80–83 mg/kg/h | 1.66 mL/kg/h | 0.83 mL/kg/h |
| Maintenance — average adult | 120–138 mg/kg/h | 2.76 mL/kg/h | 1.38 mL/kg/h |
| Maintenance — regular drinker | 184–196 mg/kg/h | 3.92 mL/kg/h | 1.96 mL/kg/h |
| During dialysis — non-drinker or child | 200–213 mg/kg/h | 4.26 mL/kg/h | 2.13 mL/kg/h |
| During dialysis — average adult | 240–268 mg/kg/h | 5.36 mL/kg/h | 2.68 mL/kg/h |
| During dialysis — regular drinker | 308–326 mg/kg/h | 6.52 mL/kg/h | 3.26 mL/kg/h |
Ethanol can also be added to peritoneal dialysate at 1–2 g/L.1
Monitoring
"Blood monitoring should occur every 1–2 hours until a concentration of 1–1.5 g/L is reached and thereafter at 2–4 hourly intervals." After the loading dose, maintenance concentrations should be reduced depending on the patient's normal drinking habits and any concomitant treatments.1
"Patients treated with ethanol require close monitoring preferably in a critical care area because of the risk of CNS and respiratory depression."1
Safety
The obvious hazard
You are deliberately intoxicating a patient who may already have a reduced conscious level from the poisoning, and who has a metabolic acidosis. CNS and respiratory depression are the anticipated effects, not the adverse ones, which is why the label asks for critical care.
Metabolic effects
Contraindications and interactions
- Contraindication: known hypersensitivity to alcohol.1 That is the entire list.
- Disulfiram-like reactions with chlorpropamide, metronidazole and some cephalosporins.1
- Orthostatic hypotension with vasodilators.1
- Aggravates peptic ulcer disease and hepatic impairment.1
- Enhanced CNS depression with hypnotics, antihistamines, muscle relaxants, opioid analgesics, antiepileptics, antidepressants and tranquillisers.1
- Women and older people may be more susceptible to the adverse effects.1
The other licensed indication
The same product was licensed for neurolysis — "severe and chronic pain including that caused by trigeminal neuralgia may be relieved by injection of alcohol close to the nerve", from 0.2 mL for a small nerve root up to 10 mL for coeliac plexus blockade, ideally with radiographic needle placement.1 Two entirely different uses of the same ampoule, and a reason to read the label rather than the drug name.
Practical use in the ED
- Use fomepizole if you can get it. No sedation, no levels, fixed schedule, and a clean dialysis rule. Ethanol is the fallback, not the first choice.
- Find out what your pharmacy actually holds. There is no supplied UK injectable ethanol product; what exists locally may be a specials import or nothing at all.
- Do not improvise with oral spirits. It is described in the literature and in resource-limited practice, but the dose calculation, the aspiration risk in a drowsy patient and the absence of a reliable concentration make it a last resort to be undertaken on explicit poisons-service advice.
- If ethanol is running, treat the level as the endpoint — 1–1.5 g/L, checked 1–2 hourly initially. An untitrated infusion is not treatment.
- Increase the rate when dialysis starts, roughly doubling it, and remember peritoneal dialysate can be supplemented at 1–2 g/L.
- Do not give activated charcoal. Ethanol, methanol and ethylene glycol all carry strong recommendations against it in the 2026 CTRC guideline.2
- Escalate to critical care early — this is a sedating infusion in an acidotic patient who is likely to need dialysis.
Critical appraisal
Ethanol and fomepizole have never been compared in a randomised trial and never will be. The mechanism is identical; the argument is entirely about usability, and fomepizole wins every part of it except cost and availability. That is a legitimate basis for displacement, and the displacement has happened.
What is less often acknowledged is what has been lost. The UK now has a licensed antidote for ethylene glycol only (fomepizole's section 4.1 does not mention methanol), and the product that was licensed for methanol — this one — is discontinued. On the labels alone, the UK has no licensed antidote for methanol poisoning at all. Practice fills the gap with off-label fomepizole, and correctly so, but the regulatory position is worth knowing before an outbreak rather than during one.
References
- 1Dehydrated Alcohol (Absolute Alcohol) BP for Injection — Summary of Product Characteristics. electronic Medicines Compendium, product 3609. Listed as discontinued; SmPC accessed 4 September 2026. Sections 4.1–4.5. Source of the methanol indication, the full loading and maintenance dose table including the dialysis rows, the 1–1.5 g/L target and monitoring intervals, the central venous catheter and critical care statements, the peritoneal dialysate concentration, the neurolysis indication, the hypersensitivity contraindication and the interaction list.
- 2Hoegberg LCG, Gosselin S, Buckley NA, Wood DM, et al. Recommendations from the Clinical Toxicology Recommendations Collaborative on the administration of activated charcoal in acute oral overdose. Clinical Toxicology 2026;64(6):419–475. PubMed 41906697. Table 4 and Figure 1: ethanol and the toxic alcohols carry strong recommendations against activated charcoal, and alcohols head the list of poisons not clinically significantly adsorbable. Full text read 4 September 2026.
- 3National Poisons Information Service. TOXBASE · NPIS 0344 892 0111. Required: there is no supplied UK intravenous ethanol product, and fomepizole's UK licence does not cover methanol.