Everything You Need to Know About Methanol Poisoning

Although there are usually few cases of methanol poisoning, they're very serious. They can lead to death if not treated in time. Learn more in this article.
Everything You Need to Know About Methanol Poisoning

Last update: 03 October, 2021

Methanol poisoning is a very real problem.

Methanol is a type of alcohol that is colorless and volatile at room temperature. It’s also known as wood alcohol or burning alcohol. It’s commonly used in industry, laboratories, and in the home, as it can be found in many cleaning products, antifreeze, paints, and varnishes.

Intoxication can occur accidentally by handling these products via inhalation. However, in many countries, the most common mode of intoxication is voluntary in the case of suicides.

In addition, there’s fraudulent use of this substance as a substitute for ethanol in clandestinely manufactured alcoholic beverages. They cause several people to become intoxicated at the same time, resulting in an outbreak in the emergency department.

Methanol intoxication is very rare. However, it has a high mortality rate, between 26 and 50 %. On the other hand, in cases where it doesn’t cause death, it leaves a large number of neurological and visual sequelae, including blindness.

Therefore, in this article, we’ll tell you everything you need to know about methanol poisoning, its symptoms, and what to do in case you or a friend or relative is poisoned by this substance.

What is methanol and where is it found?

As we’ve said, methanol is a colorless, volatile, flammable, and non-drinkable type of alcohol. It’s toxic to our body, unlike ethanol, which is in alcoholic beverages. We can obtain it from the distillation of wood, although it can be synthesized from carbon monoxide or methane.

It produces, among others:

  • Antifreeze in car windshield washer fluid and natural gas pipes.
  • Solvents are used in industry to produce inks, resins, adhesives, and dyes. Also, as a solvent to manufacture cholesterol medications, antibiotics, vitamins, and hormones.
  • Fuel for energy production.
  • Methanol is naturally present in many foods such as fruits and vegetables. Methanol helps regulate human genetic activity and facilitates food metabolism. However, the doses in these foods are very small and not at all toxic.
  • Methanol is used to denature ethanol. It prevents people from drinking products containing ethanol, such as mouthwash and fuel mixtures.
  • Methanol can be produced during the production of alcoholic beverages or distillation. In authorized alcoholic beverages, methanol is below toxic doses, but this isn’t the case in those made clandestinely.
  • Aspartame is an artificial sweetener that, when digested in the body, is converted into phenylalanine, aspartic acid, and methanol. However, the amounts produced by the digestion of aspartame are lower than the exposure probably produced by fruits and vegetables.

The dose at which methanol begins to be toxic is 100 mg/kg, which would be equivalent to about 30 milliliters of pure methanol. The toxic level in blood is from 0.2 g/L onwards. Some foods have methanol. However, they’re far from reaching the toxic dose.

alcohol addiction

Why is methanol so dangerous?

When we ingest methanol, the intestine absorbs it and reaches the blood. By itself, methanol isn’t toxic, although it can depress the nervous system, making us dizzy or drowsy. However, the liver breaks down methanol into formic acid, which is a very toxic substance.

What does formic acid do in our body?

Our blood has a level of acidity or pH that has to be kept stable so that the cells in our body can function well. The range of this acidity has to be around 7.35-7.45. If it is less than 7.35 it means that the pH is low, i.e., the blood is more acidic than normal.

So, if we have formic acid in the blood, the pH decreases causing the cells to stop functioning properly and die. This process is called metabolic acidosis and, if left untreated, can be fatal.

What are the symptoms?

The onset of symptoms of methanol poisoning varies from 40 minutes to 72 hours, although symptoms usually appear within the first 12 to 24 hours. However, before this time, the person may become intoxicated by the methanol itself.

stomach ache

Symptoms and signs of intoxication usually affect:

  • Central Nervous System: In mild or moderate intoxication there is headache, dizziness, lethargy, incoordination to move, or simply a state of drunkenness similar to that of ethyl intoxication. However, in severe cases, convulsions, coma, and cerebral edema may occur.
  • Eyes: There are alterations of the vision that appear as blurred vision, photophobia, and dilation of the pupils. Loss of vision and irreversible blindness due to optic nerve atrophy may also develop as a result of the direct toxicity of formic acid on the eyes.
  • Gastrointestinal system: Due to its irritant action, nausea, vomiting, and stomach pain occur. However, if left untreated, intoxication can affect the pancreas, causing it to become inflamed, and the liver.
  • Other manifestations: To compensate for the acidity of the blood, the body tries to eliminate acid by expelling CO2, which gives acid products. In other words, the body starts to breathe very fast and shortness of breath appears.

What should I do if I have methanol poisoning?

If you think you may have ingested or inhaled methanol you should go to the emergency room immediately. The same applies if a family member or friend has taken methanol to harm themselves.

At the hospital, if no more than two or three hours have passed since the ingestion, doctors can perform a stomach pump to prevent the methanol from being absorbed and avoid methanol poisoning.

However, we may not realize that we have methanol poisoning since methanol doesn’t produce symptoms until after one or two days. Although in these situations you would need to go to the emergency room immediately, you won’t need stomach pumping, but other treatments:

  • General measures: Stabilize the affected person by giving bicarbonate to increase pH and decrease acidity, hydration and respiratory support, folinic acid (to avoid ocular sequelae), and vitamins.
  • Avoid conversion of formic acid to methanol in the liver: Ethanol uses the same enzyme as methanol to metabolize in the liver and has a much higher affinity. Therefore, to prevent methanol from using this enzyme and producing formic acid, doctors inject ethanol. Doctors can also use a drug called Fomepizole to inhibit this enzyme, but it’s very difficult to obtain and very expensive.
  • Hemodialysis: This cleans the patient’s blood of methanol and formic acid.

The doctor must perform these treatments quickly to avoid sequelae, especially blindness, and the death of the intoxicated person.

It might interest you...
How to Prevent Food Poisoning
Step To Health
Read it in Step To Health
How to Prevent Food Poisoning

Handling and cooking foods correctly is the determining factor in preventing food poisoning. We'll explain in detail in this article.