How much alcohol intake is required to trigger withdrawal?

Question

Daily heavy alcohol users frequently experience a withdrawal syndrome if they suddenly stop drinking. I’m pretty confident that 2 standard drinks per day is rarely enough to trigger withdrawal, and those who drink 8-10/day almost always experience some withdrawal, but I’m not clear on where the line is. I realize there is a lot of inter-individual variability in this, but I’m wondering if it has been investigated systematically. The duration of use clearly also affect this.*

Ideally, I would like to see a 3D graph showing the likelihood of withdrawal (at some threshold level of severity) according to daily dosage and length of exposure. Not being confident that this exists, any studies looking into the threshold daily intake required to trigger withdrawal would be welcome.

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_{*There’s also a (somewhat controversial) concept known as ‘kindling’ whereby repeated detox attempts may cause worsening of withdrawal, but for the purpose of this question I’m assuming a first detox attempt.}

Answer 1

I don't think that you will find a definitive answer on this, unfortunately. There are too many factors on an individual basis to make it a blanket kind of projection. The closest that I found for any kind of writeup that addresses it is this published article.

The pertinent part of that is this section here:

How Much Alcohol Must Be Ingested (and over what period) for a Person to Develop Alcohol Dependence and to Be at Risk for Alcohol Withdrawal?

There is no absolute relationship between pattern of alcohol use and the risks of physiologic dependence and withdrawal, which most likely reflects the significant number of variables, in addition to duration and quantity of alcohol use, that can contribute to dependence and withdrawal risk for a given individual. Some of these additional variables include age, medical comorbidities (such as hepatic dysfunction), concomitant medication use, and seizure threshold.

It has been easier to quantify the risk of benzodiazepine withdrawal, based on degree of benzodiazepine use (even though benzodiazepines act at the same receptor as does alcohol and are cross-reactive with it). For example, daily use of 20 mg of diazepam for 3 weeks or longer is believed to be sufficient to induce physiologic dependence.3 However, the shorter half-life of alcohol (1–2 hours) has made similar predictions elusive in the case of alcohol abuse. In general, any suspicion of daily alcohol use over several weeks or more, regardless of quantity, should raise concern over possible alcohol withdrawal.

So, while you can make some possible predictions, you may just have to look at the drinking history pattern and project from that, and make preparations for withdrawal symptoms to occur in cases of extended consumption, even if it the first time the patient has consumed in that manner.

As far as the preparations, there is this article which addresses the clinical features, assessment and management of AWS (Alcohol Withdrawal Syndrome).