- Methionine is an antidote that can be used to treat paracetamol overdosage, although the standard antidote is n-acetylcysteine, given intravenously.
- The effectiveness of methionine when combined in tablets with paracetamol to try to render an overdose harmless is unknown - clinical trials involving overdoses obviously cannot be carried out.
- All but a very small number of overdoses are taken with the intention of causing self harm. Paracetamol/methionine combinations would probably be avoided by people who intend to take a drug overdose to commit suicide or cause self harm.
- Paracetamol/methionine combinations are of no benefit to people who use paracetamol normally. Methionine neither increases the effectiveness of paracetamol nor its safety in normal doses.
- Adding constituents that are not useful to the vast majority of people using the medicine is considered bad practice by many doctors and members of the public.
- Methionine occurs naturally in foods but animal experiments show that at higher doses it may have side-effects including nausea; vomiting; drowsiness; enlargement of the spleen, kidney, and liver; and possible vitamin deficiency. Methionine should not be taken by people who have liver injury or who have schizophrenia. In people who have methionine intolerance, methionine supplementation may lead to increased risk of cardiovascular disease. Methionine may also stimulate the growth of certain common pre-existing cancer tumours.