How alcohol damages the liver
The liver metabolises alcohol via a pathway that produces acetaldehyde — a toxic compound more damaging than alcohol itself. Acetaldehyde damages liver cell DNA and proteins, triggers inflammation, and promotes fibrosis (scarring). When alcohol arrives faster than the liver can process it, and consistently over time, this damage accumulates.
Stage 1: Alcoholic fatty liver (steatosis)
The earliest and most reversible stage. Fat accumulates in liver cells in almost everyone who drinks regularly above NHS guidelines. It typically causes no symptoms and is fully reversible with abstinence or significant reduction in drinking.
Stage 2: Alcoholic hepatitis
Inflammation of the liver, ranging from mild to severe. Mild alcoholic hepatitis may be reversible; severe alcoholic hepatitis has a 28-day mortality of around 30–50%.
Stage 3: Cirrhosis
Extensive scarring replacing normal liver tissue. Cirrhosis is largely irreversible — the scarring itself cannot be undone, though progression can be halted by stopping drinking. Advanced cirrhosis leads to liver failure, bleeding varices, and hepatic encephalopathy.
Alcoholic liver disease is typically asymptomatic until it is advanced. Most people with early cirrhosis have no symptoms — it is often only discovered incidentally or when complications occur. By then, significant damage has occurred.
How many units causes damage?
The NHS 14-unit guideline
The NHS recommends no more than 14 units per week, spread over at least 3 days, with several alcohol-free days per week. This guideline is set as a low-risk threshold — below it, liver damage is uncommon in most people. Above it, risk increases in a roughly linear fashion.
Individual variation
Liver damage risk varies substantially between individuals. Women develop liver damage at lower consumption levels than men (due to lower body water content and alcohol dehydrogenase activity). Genetic variants in alcohol metabolism enzymes, obesity, and hepatitis C infection all dramatically amplify risk.
Regular alcohol-free days are not just a bureaucratic requirement of the guidelines — they are clinically important. The liver requires time without incoming alcohol to complete repair processes. Drinking every day, even within 14 units, is riskier than the same units concentrated on fewer days with alcohol-free days interspersed.
Liver damage risk by consumption level
| Weekly Units | Risk Level | Likely Liver Status |
|---|---|---|
| 0 | None | Healthy baseline |
| 1–14 | Low | Usually normal; fatty liver possible at upper end |
| 15–35 | Moderate–High | Fatty liver likely; fibrosis risk increasing |
| 35–50 | High | Significant fibrosis risk; hepatitis possible |
| 50+ | Very High | High cirrhosis risk over time |
Frequently asked questions
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