How does Methionine work?

In acetaminophen poisoning, methionine prevents the breakdown products of acetaminophen from damaging the liver.

Are there safety concerns?

Methionine seems to be safe for treating acetaminophen poisoning under the supervision of a healthcare professional. It may be unsafe to use methionine to self-medicate if used in amounts larger than those normally found in foods. Methionine can increase blood levels of homocysteine, a chemical that might cause heart disease. Methionine might also promote the growth of some tumors.

Do not use methionine if:
  • You are pregnant or breast-feeding.
  • You have hardening of the arteries (atherosclerosis).
  • You have cancer.
  • You have a genetic disorder called methylenetetrahydrofolate reductase (MTHFR) deficiency.

Dosing considerations for Methionine.

The following doses have been studied in scientific research:

  • For acetaminophen (Tylenol) poisoning: 2.5 grams of methionine every 4 hours for 4 doses to prevent liver damage and death. Methionine must be given within 10 hours of taking the acetaminophen. This should be done by a healthcare professional.

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Report Problems to the Food and Drug Administration

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.