Alcohol and its health effects

What is it?

Alcohol is the ethanol found in alcoholic drinks, and the World Health Organization describes it as a "toxic psychoactive substance with dependence-producing properties". MedlinePlus says it is a central nervous system depressant that can change mood, behaviour and self-control, and impair memory, clear thinking and motor coordination.

A standard drink contains about 14 grams of pure alcohol according to MedlinePlus and the NIAAA, which is roughly equivalent to 12 ounces (about 355 ml) of regular beer at 5%, or 5 ounces (about 150 ml) of wine at 12%, or 1.5 ounces (about 45 ml) of distilled spirits at 40%.

The CDC and MedlinePlus define "moderate drinking" as one drink or less a day for women, and two drinks or less a day for men. As for "binge drinking", the NIAAA, CDC and MedlinePlus define it as a pattern of drinking that raises blood alcohol concentration to 0.08% or more, typically with four or more drinks for women or five or more drinks for men within about two hours.

"Heavy drinking" is defined by the CDC and NIAAA as eight or more drinks a week for women, and 15 or more drinks a week for men. The NIAAA also describes "high-intensity drinking" as twice the binge drinking threshold or more: eight or more drinks for women, and 10 or more drinks for men on a single occasion.

The World Health Organization stresses that there is no level of alcohol consumption that is completely free of risk, and that the level of risk depends on the amount, frequency, health condition, age, sex, individual characteristics and context of drinking, and that most alcohol-related harm comes from repeated binge drinking or persistent heavy drinking.

Why it matters

The World Health Organization says alcohol has a causal role in more than 200 diseases, injuries and health conditions, although the burden of only 31 of them can currently be measured globally. The organisation estimates that alcohol causes 2.6 million deaths worldwide each year (2019 data): 1.6 million of them from noncommunicable diseases, 700,000 from injuries, and 300,000 from communicable diseases.

According to the organisation, men accounted for about 2 million of these deaths and women about 600,000, and the highest death rates per 100,000 population were in the European (52.9) and African (52.2) regions, and the 20–39 age group was the most affected at 13% of all alcohol-related deaths. The rate of these deaths per 100,000 population globally fell by 20.2% between 2010 and 2019.

The organisation estimates that about 400 million people aged 15 and over (7% of this group) had alcohol use disorders, of whom 209 million (3.7%) had alcohol dependence. The organisation also attributes to alcohol 474,000 deaths from cardiovascular disease, 4.4% of cancers diagnosed worldwide and 401,000 cancer deaths, and 298,000 road traffic deaths (156,000 of them caused by someone other than the deceased drinking).

The World Health Organization describes alcohol as a scientifically established carcinogen, and lists among the cancers linked to it: breast, liver, head and neck, oesophagus, colon and rectum. The NIAAA states (citing the US National Cancer Institute) that there is strong scientific consensus that drinking alcohol can cause several types of cancer, and that just one drink a day may raise a woman's risk of breast cancer by 5% to 15% compared with women who do not drink.

According to the CDC in the United States, drinking any type of alcoholic beverage is linked to an increased risk of cancer, and the risk of some types (including breast cancer in women) rises with any amount of alcohol, and the agency attributes more than 20,000 deaths a year in the United States to alcohol-related cancers.

For the heart and vessels, the NIAAA states that long-term heavy drinking raises the risk of high blood pressure, heart rhythm disturbance and a faster heart rate, may weaken the heart muscle (cardiomyopathy), and raises the risk of ischaemic heart disease and heart attack with chronic heavy drinking, and warns that even low levels of drinking may carry some risk. It also states that alcohol interferes with communication pathways in the brain and can raise the risk of stroke.

The CDC states that long-term health effects of excessive alcohol use include: liver disease, heart disease, stroke, a weakened immune system, alcohol use disorder, and mental health problems including depression and anxiety, and memory problems that may reach dementia.

For the liver, the NIAAA states that heavy drinking can cause a progression of conditions: fat build-up in the liver, then fatty liver inflammation, then hepatitis, then fibrosis, then cirrhosis, and may reach hepatocellular carcinoma. See also alcohol-related liver disease.

As for the pancreas, the NIAAA states that long-term alcohol misuse may lead to pancreatitis, which may impair digestive enzyme production and blood sugar regulation, and that chronic pancreatitis is a risk factor for pancreatic cancer and diabetes.

For immunity: the NIAAA states that binge drinking on a single occasion slows the body's ability to fight infection for up to 24 hours afterwards, and that chronic heavy drinking can weaken multiple parts of the immune response and slow recovery from tissue injury, and may speed the progression of HIV infection in those who have it.

The World Health Organization states that alcohol is also linked to injuries from road traffic crashes, falls, drowning, burns, sexual assault, intimate partner violence and suicide, and to a causal relationship with tuberculosis and with the transmission or worsening course of HIV infection, as well as family, work and financial problems and unemployment with long-term harmful or hazardous use.

In pregnancy, the World Health Organization states that a pregnant woman's drinking raises the risk of fetal alcohol spectrum disorders (the most severe being fetal alcohol syndrome), and may raise the risk of miscarriage, stillbirth and preterm birth.

Key points

There is no level of alcohol consumption that is completely free of risk according to the World Health Organization; most of the harm comes from binge drinking or persistent heavy drinking.

A standard drink is about 14 grams of pure alcohol (MedlinePlus, NIAAA).

Moderate drinking: one drink a day or less for women, and two drinks a day or less for men (CDC, MedlinePlus).

Binge drinking: a blood alcohol concentration of 0.08% or more, usually 4 or more drinks for women or 5 or more for men within about two hours (NIAAA, CDC, MedlinePlus).

Heavy weekly drinking: 8 or more drinks for women or 15 or more for men (CDC, NIAAA).

Alcohol is a scientifically established carcinogen, and about 4.4% of cancers diagnosed worldwide and 401,000 cancer deaths a year are attributed to it (World Health Organization).

The World Health Organization attributes 2.6 million deaths a year worldwide to alcohol, including 474,000 from heart and vascular disease and 298,000 in road traffic crashes.

According to the CDC, about 178,000 people die each year in the United States from excessive alcohol use, of whom more than 20,000 die from alcohol-related cancers.

How to put it into practice

The US Dietary Guidelines (as cited by MedlinePlus) advise adults of legal drinking age not to drink alcohol at all, or to drink in moderation if they choose to drink, and state that drinking less is better for health than drinking more.

For those who want to cut down on how much they drink, the NIAAA (Rethinking Drinking website) suggests practical steps including: tracking the amount you drink (by writing it on a card, calendar or phone note before each drink), learning standard drink sizes and measuring them at home, and setting the number of drinking days and drinks per day while planning alcohol-free days.

The NIAAA also suggests: finding alternatives such as activities, hobbies and new healthy friendships to fill free time and manage mood and stress, avoiding the people, places, times or feelings that trigger drinking, and keeping little or no alcohol at home.

When you feel the urge to drink, the NIAAA advises remembering your reasons for wanting to change, or talking to someone you trust, or occupying yourself with a healthy activity that distracts from the urge until it passes, and preparing a polite and firm refusal for when you are offered a drink.

The NIAAA suggests trying two or three of these steps for a week or two and then adding more when needed, and that if the amount you drink has not fallen after two to three months, it may be helpful to consider stopping completely or seeking help from a professional.

The CDC states that staying away from places with many alcohol outlets and promotion is linked to less drinking, because people tend to drink less when they are not surrounded by it.

The drinking limits or plan to reduce it that suit you are determined by your doctor according to your health condition and medicines.

Special groups

Pregnancy and breastfeeding: there is no known safe level of alcohol consumption during pregnancy according to the World Health Organization, which links it to fetal alcohol spectrum disorders, miscarriage, stillbirth and preterm birth. MedlinePlus lists pregnant women and those trying to become pregnant among the groups who should not drink alcohol at all.

People with liver disease or other health conditions: MedlinePlus states that people with health conditions that could be made worse by alcohol should not drink at all; and for anyone diagnosed with an alcohol-related liver disease (see alcohol-related liver disease), discuss with the doctor whether any amount of drinking is suitable for them.

People taking medicines: MedlinePlus states that people taking medicines that may interact with alcohol should not drink at all, and any decision about alcohol with a particular medicine is discussed with the doctor or pharmacist, and do not change any medicine or its dose on your own.

People below the legal drinking age: MedlinePlus and the CDC state that any drinking below the legal age (21 years in the United States according to these two sources) is classed as unsafe drinking; the legal drinking age differs between countries.

People recovering from alcohol use disorder, or who cannot control how much they drink: MedlinePlus lists them among the groups who should not drink alcohol at all.

Before driving, operating machinery or any task needing skill, coordination and alertness: MedlinePlus advises not drinking alcohol at all beforehand.

The most affected age group: the World Health Organization states that people aged 20 to 39 are relatively the most affected by alcohol-related deaths worldwide (13% of the total).

Risks and cautions

Alcohol poisoning and binge drinking: the CDC and MedlinePlus state that binge drinking raises the risk of injury, traffic crashes, alcohol poisoning and violence (as perpetrator or victim), and the World Health Organization states that alcohol also contributes to falls, drowning, burns, sexual assault, partner violence and suicide.

High-intensity drinking: the NIAAA describes it as twice the binge drinking threshold or more (8 or more drinks for women or 10 or more for men on a single occasion), and it is a higher-risk pattern than usual binge drinking.

The myth that "moderate drinking is completely safe": MedlinePlus says moderate drinking itself can raise the risk of death from some cancers and heart disease, and the NIAAA states that even low levels of drinking may carry some cardiovascular risk.

Alcohol interaction with medicines: MedlinePlus states that people taking medicines that may interact with alcohol should not drink at all, and that this is discussed with the doctor or pharmacist; do not start or stop any medicine because of alcohol without consulting a specialist.

Temporary weakening of immunity: the NIAAA states that binge drinking on a single occasion slows the body's ability to fight infection for hours that may extend to 24 hours afterwards.

Alcohol use disorder: the NIAAA and MedlinePlus state that binge and heavy drinking raise the risk of alcohol use disorder, and that the risk rises with the amount drunk in a single day and with continuing a pattern of excess over time.

Limits of this information

The figures and definitions for a standard drink, moderate, binge and heavy drinking here are mainly drawn from US sources (CDC, NIAAA and MedlinePlus); the definitions of a "standard drink" and recommended drinking limits may differ in other countries. Ask the health authority in your country for local guidelines.

World Health Organization statistics are global estimates for 2019 and population averages, and do not represent a precise prediction of any individual's risk.

The legal drinking age mentioned here (21 years) is specific to the United States according to the CDC and MedlinePlus, and the legal age and laws on the sale and obtaining of alcohol differ between countries.

This page does not cover detailed treatment or medicine recommendations for alcohol use disorder or for managing withdrawal symptoms, as these need specialist assessment; for this reason it does not mention any particular medicine or treatment plan. MedlinePlus directs anyone with such questions to a healthcare provider.

This page does not list in detail the signs of acute alcohol poisoning (such as loss of consciousness or slow breathing); in any case that worries you after drinking use the "Emergency" button at the top of the page.

Common questions