Methanol Poisoning: Symptoms, Treatment and Prevention
- Syed Hassaan Ali
- 2 days ago
- 4 min read
By Dionne Roberts, MSN, RN-BC
Methanol Toxicity: The Silent Threat
Methanol (CH3OH) is a toxic wood alcohol mostly found in household, automotive, and industrial products. Exposure to methanol occurs through ingestion, inhalation or skin exposure. Accidental methanol exposure has occurred due to errors in distillation and fermentation in the production of herbal beverages and bootleg alcohol. Significant morbidity and mortality can result if methanol toxicity is left untreated. (1)
It is estimated that thousands of people die each year from methanol poisoning. If left untreated, fatality rates can be as high as 40% depending on the toxic concentration of methanol and the amount of exposure or ingestion. (2) This is likely an underestimation due to misdiagnosis and lack of public awareness. Asia statistically has the highest prevalence of methanol poisoning worldwide, commonly seen in Indonesia, India, Cambodia, Vietnam, and the Philippines. (2)
Early Warning Signs: Symptoms Not to Ignore
Within 4 hours of ingesting methanol, symptoms may present as gastrointestinal upset such as nausea, vomiting, and abdominal pain. (1) After a latency period of about 6 to 24 hours, metabolic acidosis occurs, presenting as hyperventilation, CNS depression, and blurry or decreased vision. (1)
Ocular examination findings include papilledema (swelling of the optic nerve), abnormal redness, and dilated and twisted retinal veins due to compromised blood flow. (3) Patients not promptly treated face permanent blindness and CNS toxicity that can result in seizures, coma, and death. (1)
Why Methanol is so Dangerous: Understanding its Toxic Effects
Methanol is an alcohol similar to ethanol (grain alcohol), which is what is consumed in alcoholic beverages. Both methanol and ethanol are colorless, flammable, and have a similar smell, but their chemical structures are different. Methanol is composed of one carbon atom, while ethanol has two carbon atoms. (4)
The one-carbon difference affects how methanol is metabolized in the body, making it much more toxic than ethanol. The chemical breakdown of ethanol is acetaldehyde, which is toxic to the body, but is quickly converted to acetate, also known as acetic acid, found in vinegar. Acetate serves as an energy source for the body and as a precursor for lipid synthesis. (4)
By contrast, methanol is converted to formaldehyde and then to formic acid, which poisons the mitochondria, the cells' powerhouses. Formic acid causes severe metabolic acidosis, which leads to central nervous system depression, resulting in unconsciousness, coma, and retinal damage leading to blindness. The retinas are rich in active mitochondria and are sensitive to acidosis-induced damage. (4)
Methanol poisoning is not always fatal if the amount ingested is small and medical treatment is started immediately; however, permanent vision damage can occur even at non-lethal doses. (4)
Fast Treatment Saves Lives
Rapid treatment of methanol poisoning in a hospital is the key to survival and to lessen vision damage. Initially, 1 to 2 g/kg of activated charcoal is given by mouth or as a suspension via nasogastric tube, followed by 30 to 50 ml of sorbitol to stimulate bowel movements. (1)
Formepizole is the preferred treatment for methanol poisoning because it inhibits the metabolism and conversion of methanol to the highly toxic formic acid. (1) If formepizole is not available, grain alcohol (ethanol) can be used. It acts as a competitor, slowing the breakdown of methanol and giving the body time to eliminate it through the lungs, urine, and even perspiration. (5)
Further treatment involves supportive care, including intravenous isotonic bicarbonate, which increases methanol elimination in urine, as well as the initiation of hemodialysis. (1)
Prevention Tips for Consumers
Methanol can appear in alcoholic beverages in several ways. Sometimes it is done deliberately and illegally during or after processing as a cheaper way to increase the alcohol content. Also, traditional brewing methods can inadvertently introduce methanol through unregulated fermentation practices. (4)
Drinking at reputable establishments can reduce the risk of methanol poisoning but does not eliminate it completely. The best practices include making smart drink choices.
Choose labeled beers, wines and ciders, and select premixed cocktails in sealed cans and bottles.
Avoid liqueur-based cocktails, spirits on the rocks, or any drinks presented in jugs, buckets and shots.
Be suspicious of unusually inexpensive drinks claiming to be a popular labeled brand, as they could be counterfeit.
Never accept drinks that have unlabeled bottles or cans, free or "complimentary' shots, or homemade, roadside or 'bootleg' alcohol.
Seek urgent medical care if methanol poisoning is suspected.
Additional Reading
Victims of methanol poisoning in Laos
Melbourne Teen Holly Bowles
Melbourne Teen Bianca Jones
Sources:
“Methanol Poisoning.” Renal and Urology News, 30 Jan. 2024, https://www.renalandurologynews.com/ddi/methanol-poisoning/.
Methanol Poisoning. https://methanolpoisoning.msf.org/en/outbreaks-worldwide/.
Optic Disc Oedema: 5 Dangerous Causes & Signs - Liv Hospital. 29 Dec. 2025, https://int.livhospital.com/optic-disc-oedema-5-dangerous-causes-signs/.
Musgrave, Ian. “What Is Methanol? How Does It Get into Drinks and Cause Harm?” The Conversation, 20 Nov. 2024, https://doi.org/10.64628/AA.65ftcj3fj.
What Is Methanol and How Does It Affect the Body? 22 Nov. 2024, https://www.bbc.com/news/articles/cn42rnp4n9jo.
Partying Safely. 22 Oct. 2025, https://www.smartraveller.gov.au/before-you-go/safety/partying#methanol.
Assessed and Endorsed by the MedReport Medical Review Board
