Alcohol intolerance

Alcohol intolerance may occur in ME/CFS. It usually develops after the onset of the illness, where the patient was previously able to tolerate alcohol. It may form part of a wider range of allergies and sensitivities that may develop during the course of the illness.

A 2019 study by Stanford ME/CFS Initiative reported that 66% of subjects meeting the Fukuda 1994 CFS criteria were less able to tolerate alcohol compared to their pre-illness state.

Prevalence

 * 1995, Katrina Berne, PhD, reported an estimated prevalence of 45-75% for alcohol intolerance (although she notes that this symptom may be underreported and therefore more prevalent than indicated).
 * 2001, In a Belgian study, 59.5% of patients meeting the Fukuda criteria and 63.7% of patients meeting the Holmes criteria, in a cohort of 2073 CFS patients, reported alcohol intolerance.ref>

Possible causes

 * Channelopathy has been proposed as a mechanism of the illness which would explain intolerance to alcohol and other drugs.
 * Gut fermentation problems
 * Alcohol is a depressant of the central nervous system, which tends to be hyper-reactive in people with ME/CFS
 * Alcohol is toxic for the liver, and many people with ME/CFS have suboptimal liver function
 * Alcohol can interfere with the methylation cycle
 * Alcohol is a vasodilator - this will exacerbate vascular symptoms such as neurally mediated hypotension or POTS

Potential treatments
If a patient presents with alcohol intolerance, alcohol should be avoided, including that in mouthwashes and herbal tinctures.