There are reliable tests for the actual use of alcohol, one common test being that of blood alcohol content (BAC). These tests do not differentiate alcoholics from non-alcoholics; however, long-term heavy drinking does have a few recognizable effects on the body, including:

- Macrocytosis (enlarged MCV)

- Elevated GGT

- Moderate elevation of AST and ALT and an AST: ALT ratio of 2:1

- High carbohydrate deficient transferrin (CDT)

With regard to alcoholism, BAC is useful to judge alcohol tolerance, which in turn is a sign of alcoholism.

However, none of these blood tests for biological markers is as sensitive as screening questionnaires.

The World Health Organization, the European Union and other regional bodies, national governments and parliaments have formed alcohol policies in order to reduce the harm of alcoholism. Targeting adolescents and young adults is regarded as an important step to reduce the harm of alcohol abuse. Increasing the age at which licit drugs of abuse such as alcohol can be purchased, the banning or restricting advertising of alcohol has been recommended as additional ways of reducing the harm of alcohol dependence and abuse. Credible, evidence based educational campaigns in the mass media about the consequences of alcohol abuse have been recommended. Guidelines for parents to prevent alcohol abuse amongst adolescents, and for helping young people with mental health problems have also been suggested.

The Alcohol Use Disorders Identification Test (AUDIT) is considered the most accurate alcohol screening tool for identifying potential alcohol misuse, including dependence. It was developed by the World Health Organisation, designed initially for use in primary healthcare settings with supporting guidance.

Different countries recommend different maximum quantities. For most countries, the maximum quantity for men is 140 g–210 g per week. For women, the range is 84 g–140 g per week. Most countries recommend total abstinence during pregnancy and lactation.

Preventing or reducing the harm has been called for via increased taxation of alcohol, stricter regulation of alcohol advertising and the provision of brief Interventions. Brief Interventions for alcohol abuse reduce the incidence of unsafe sex, sexual violence, unplanned pregnancy and, likely, STD transmission. Information and education on social norms and the harms associated with alcohol abuse delivered via the internet or face-to-face has not been found to result in any meaningful benefit in changing harmful drinking behaviours in young people.

According to European law, individuals who are suffering from alcohol abuse or other related problems cannot be given a license, or if in possession of a license cannot get it renewed. This is a way to prevent individuals driving under the influence of alcohol, but does not prevent alcohol abuse per se.

An individual's need for alcohol can depend on their family's alcohol use history. For instance, if it is discovered that their family history with alcohol has a strong pattern, there might be a need for education to be set in place to reduce the likelihood of reoccurrence (Powers, 2007). However, studies have established that those with alcohol abuse tend to have family members who try to provide help. In many of these occasions the family members would try to help the individual to change or to help improve the individual's lifestyle.

Alcoholic liver disease is a major public health problem. For example, in the United States up to two million people have alcohol-related liver disorders. Chronic alcohol abuse can cause fatty liver, cirrhosis and alcoholic hepatitis. Treatment options are limited and consist of most importantly discontinuing alcohol consumption. In cases of severe liver disease, the only treatment option may be a liver transplant from alcohol abstinent donors. Research is being conducted into the effectiveness of anti-TNFs. Certain complementary medications, e.g., milk thistle and silymarin, appear to offer some benefit. Alcohol is a leading cause of liver cancer in the Western world, accounting for 32-45% of hepatic cancers. Up to half a million people in the United States develop alcohol-related liver cancer. Moderate alcohol consumption also increases the risk of liver disease.

If the symptoms of alcohol dementia are caught early enough, the effects may be reversed. The person must stop drinking and start on a healthy diet, replacing the lost vitamins, including, but not limited to, thiamine. Recovery is more easily achievable for women than men, but in all cases it is necessary that they have the support of family and friends and abstain from alcohol.

The existence of alcohol-related dementia is widely acknowledged but not often used as a diagnosis, due to a lack of widely accepted, non-subjective diagnostic criteria; more research is needed. Criteria for alcohol-induced persistent dementia in the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) include the following:

There are problems with DSM diagnostic criteria, however. Firstly, they are vague and subjective. Furthermore, the criteria for diagnosis of dementia were inspired by the clinical presentation of Alzheimer's disease and are poorly adapted to the diagnosis of other dementias. This has led to efforts to develop better diagnostic models.

Oslin (Int J Geriatr Psychiatry 1998) proposed alternative clinical diagnostic criteria which were validated. The criteria include a clinical diagnosis of dementia at least 60 days after last exposure to alcohol, significant alcohol use (i.e. minimum 35 standard drinks/week for males and 28 for women) for more than 5 years, and significant alcohol use occurring within 3 years of the initial onset of cognitive deficits. Oslin proposed the new and refined diagnostic criteria for Alcohol Related Dementia because he hoped that the redefined classification system would bring more awareness and clarity to the relationship between alcohol use and dementia.

Oslin's proposed classification of ARD:

- "Definite" Alcohol Related Dementia

At the current time there are no acceptable criteria to definitively define Alcohol Related Dementia.

- "Probable" Alcohol Related Dementia

Definitive diagnosis relies on a blood test for alcohol, usually performed as part of a toxicology screen.

Law enforcement officers in the United States of America often use breathalyzer units and field sobriety tests as more convenient and rapid alternatives to blood tests.

There are also various models of breathalyzer units that are available for consumer use. Because these may have varying reliability and may produce different results than the tests used for law-enforcement purposes, the results from such devices should be conservatively interpreted.

Many informal intoxication tests exist, which, in general, are unreliable and not recommended as deterrents to excessive intoxication or as indicators of the safety of activities such as motor vehicle driving, heavy equipment operation, machine tool use, etc.

For determining whether someone is intoxicated by alcohol by some means other than a blood-alcohol test, it is necessary to rule out other conditions such as hypoglycemia, stroke, usage of other intoxicants, mental health issues, and so on. It is best if his/her behavior has been observed while the subject is sober to establish a baseline. Several well-known criteria can be used to establish a probable diagnosis. For a physician in the acute-treatment setting, acute alcohol intoxication can mimic other acute neurological disorders, or is frequently combined with other recreational drugs that complicate diagnosis and treatment.

Alcoholic polyneuropathy is very similar to other axonal degenerative polyneuropathies and therefore can be difficult to diagnose. When alcoholics have sensorimotor polyneuropathy as well as a nutritional deficiency, a diagnosis of alcoholic polyneuropathy is often reached.

To confirm the diagnosis, a physician must rule out other causes of similar clinical syndromes. Other neuropathies can be differentiated on the basis of typical clinical or laboratory features. Differential diagnoses to alcoholic polyneuropathy include amyotrophic lateral sclerosis, beriberi, Charcot-Marie-Tooth disease, diabetic lumbosacral plexopathy, Guillain Barre Syndrome, diabetic neuropathy, mononeuritis multiplex and post-polio syndrome.

To clarify the diagnosis, medical workup most commonly involves laboratory tests, though, in some cases, imaging, nerve conduction studies, electromyography, and vibrometer testing may also be used.

A number of tests may be used to rule out other causes of peripheral neuropathy. One of the first presenting symptoms of diabetes mellitus may be peripheral neuropathy, and hemoglobin A1C can be used to estimate average blood glucose levels. Elevated blood creatinine levels may indicate renal insufficiency and may also be a cause of peripheral neuropathy. A heavy metal toxicity screen should also be used to exclude lead toxicity as a cause of neuropathy.

Alcoholism is normally associated with nutritional deficiencies, which may contribute to the development of alcoholic polyneuropathy. Thiamine, vitamin B-12, and folic acid are vitamins that play an essential role in the peripheral and central nervous system and should be among the first analyzed in laboratory tests. It has been difficult to assess thiamine status in individuals due to difficulties in developing a method to directly assay thiamine in the blood and urine. A liver function test may also be ordered, as alcoholic consumption may cause an increase in liver enzyme levels.

A normal liver detoxifies the blood of alcohol over a period of time that depends on the initial level and the patient's overall physical condition. An abnormal liver will take longer but still succeeds, provided the alcohol does not cause liver failure.

People having drunk heavily for several days or weeks may have withdrawal symptoms after the acute intoxication has subsided.

A person consuming a dangerous amount of alcohol persistently can develop memory blackouts and idiosyncratic intoxication or pathological drunkenness symptoms.

Long-term persistent consumption of excessive amounts of alcohol can cause liver damage and have other deleterious health effects.

Although there is no known cure for alcoholic polyneuropathy, there are a number of treatments that can control symptoms and promote independence. Physical therapy is beneficial for strength training of weakened muscles, as well as for gait and balance training.

Extensive epidemiological studies have demonstrated the cardioprotective effect of alcohol consumption. However the mechanism by which this occurs is not fully understood. Research has suggested several possible mechanisms, including the following.

There is a lack of medical consensus about whether moderate consumption of beer, wine, or distilled spirits has a stronger association with heart disease. Studies suggest that each is effective, with none having a clear advantage. Most researchers now believe that the most important ingredient is the alcohol itself.

The American Heart Association has reported that "More than a dozen prospective studies have demonstrated a consistent, strong, dose-response relation between increasing alcohol consumption and decreasing incidence of CHD (coronary heart disease). The data are similar in men and women in a number of different geographic and ethnic groups. Consumption of one or two drinks per day is associated with a reduction in risk of approximately 30% to 50%".

Heart disease is the largest cause of mortality in the United States and many other countries. Therefore, some physicians have suggested that patients be informed of the potential health benefits of drinking alcohol in moderation, especially if they abstain and alcohol is not contraindicated. Others, however, argue against the practice in fear that it might lead to heavy or abusive alcohol consumption. Heavy drinking is associated with a number of health and safety problems.

A logical possibility is that some of the alcohol abstainers in research studies previously drank excessively and had undermined their health, thus explaining their high levels of risk. To test this hypothesis, some studies have excluded all but those who had avoided alcohol for their entire lives. The conclusion remained the same in some studies: moderate drinkers are less likely to suffer heart disease. A paper concludes, "In this population of light to moderate drinkers, alcohol consumption in general was associated with decreased MI [myocardial infarction ] risk in women; however, episodic intoxication was related to a substantial increase in risk."

An analysis by Dr. Kaye Fillmore and colleagues failed to find significant support. Analyzing 54 prospective studies, the authors found that those studies which were free of the potential error (including former drinkers in the abstaining group) did not demonstrate significant cardiac protection from alcohol, although they continued to exhibit a J-shaped relationship in which moderate drinkers were less likely (but not at a statistically significantly level of confidence) to suffer cardiac disease than lifelong abstainers.

Dr. Arthur Klatsky noted that the flaw pointed out by Fillmore existed in one of his early studies of alcohol consumption, but that his later studies illustrating a protective effect of moderate alcohol consumption did not contain this flaw. To overcome the inherent weaknesses of all epidemiological studies, even when properly conducted, he calls for a randomized trial in which some subjects are assigned to abstain while others are assigned to drink alcohol in moderation and the health of all is monitored for a period of years.

This question of confusion of abstainers with previously heavy drinkers in epidemiologic studies is overcome with studies showing dose response effects. That is, higher amounts of alcohol consumption seem associated with greater cardiovascular benefit. Cardiology associations recommend that people who are currently nondrinkers should not start drinking alcohol.

Blackouts are commonly associated with the consumption of large amounts of alcohol; however, surveys of drinkers experiencing blackouts have indicated that they are not directly related to the amount of alcohol consumed. Respondents reported they frequently recalled having "drunk as much or more without memory loss," compared to instances of blacking out. Subsequent research has indicated that blackouts are most likely caused by a rapid increase in a person's blood-alcohol concentration. One study, in particular, resulted in subjects being stratified easily into two groups, those who consumed alcohol very quickly, and blacked out, and those who did not black out by drinking alcohol slowly, despite being extremely intoxicated by the end of the study.

In another study hospital file data showed, that of 67 participants, 39 had reported a blackout. The presence or absence of blackouts was cross-tabulated against various measures of alcohol problem severity. The presence of blackouts was associated to some degree with some indications of severity such as withdrawal and loss of control, but not with duration of problem drinking, physical complications or abnormal liver function.

The presence of blackouts was related to some measures of severity of the problem – withdrawal symptoms and loss of control. The hypotheses that blackouts either reflect a general vulnerability to the cerebral consequences of alcohol abuse or are associated with other forms of more enduring cognitive impairment did not receive any support.

In another study which looked at subjective responses to alcohol as a prime for 21st birthday alcohol consumption, subjective responses to the initial drink were viewed as a prime for more alcohol consumption during 21st birthday celebrations. Current findings show that subjective responses to alcohol have direct effects on both the final BAC achieved and on the experiences of blackouts and hangover that are not explained by level of intoxication. Where a variety of social factors, such as peer pressure and 21st birthday traditions such as 21 shots may influence the amount of alcohol people consume, their subjective experiences with alcohol have clear influences on both consumption and the physiological consequences of drinking. These physiological responses to alcohol may have a biological vulnerability that extends beyond the dose-dependent effects of alcohol.

Self reports from another study showed that 63% of patients in the study gulped their drinks rather than sipped. Five patients recollected vomiting during the drinking episode while 32 drank on an empty stomach and 41 drank more than originally planned. During the drinking episode 31% subjects described blackouts, 20% described brownouts, and 49% reported no amnesic episode.

A drug-related blackout is a phenomenon caused by the intake of any substance or medication in which short term and long term memory creation is impaired, therefore causing a complete inability to recall the past. Blackouts are most frequently associated with GABAergic drugs. Blackouts are frequently described as having effects similar to that of anterograde amnesia, in which the subject cannot recall any events after the event that caused amnesia. Research on alcohol blackouts was begun by E. M. Jellinek in the 1940s. Using data from a survey of Alcoholics Anonymous (AA) members, he came to believe that blackouts would be a good determinant of alcoholism. However, there are conflicting views whether this is true. The negative psychological effects of an alcohol-related blackout are often worsened by those who suffer from anxiety disorders. Impairment of the liver will also allow more alcohol to reach the brain and hasten the individual's blackout.

The term "blackout" can also refer to a complete loss of consciousness, or syncope.

Alcohol tolerance refers to the bodily responses to the functional effects of ethanol in alcoholic beverages. This includes direct tolerance, speed of recovery from insobriety and resistance to the development of alcoholism.

The tolerance to alcohol is not equally distributed throughout the world's population, and genetics of alcohol dehydrogenase indicate resistance has arisen independently in different cultures. In North America, Native Americans have the highest probability of developing alcoholism compared to Europeans and Asians.

Higher body masses and the prevalence of high levels of alcohol dehydrogenase in an individual increase alcohol tolerance.

Not all differences in tolerance can be traced to biochemistry. Differences in tolerance levels are also influenced by socio-economic and cultural difference including diet, average body weight and patterns of consumption.

An estimated one out of twenty people have an alcohol flush reaction. It is not in any way an indicator for the drunkenness of an individual. It is colloquially known as "face flush", a condition where the body metabolizes alcohol nearly 100-times less efficiently into acetaldehyde, a toxic metabolite. Flushing, or blushing, is associated with the erythema (reddening caused by dilation of capillaries) of the face, neck, and shoulder, after consumption of alcohol.

In general, alcohol abusers with withdrawal symptoms, such as alcoholic hallucinosis, have a deficiency of several vitamins and minerals and their bodies could cope with the withdrawal easier by taking nutritional supplements. Alcohol abuse can create a deficiency of thiamine, magnesium, zinc, folate and phosphate as well as cause low blood sugar. However, several tested drugs have shown the disappearance of hallucinations. Neuroleptics and benzodiazepines showed normalization. Common benzodiazepines are chlordiazepoxide and lorazepam. It has been shown that management has been effective with a combination of abstinence from alcohol and the use of neuroleptics. It is also possible to treat withdrawal before major symptoms start to happen in the body. Diazepam and chlordiazepoxide have proven to be effective in treating alcohol withdrawal symptoms such as alcoholic halluciniosis. With the help of these specific medications, the process of withdrawal is easier to go through, making alcoholic hallucinosis less likely to occur.

Ethanol is the type of alcohol found in alcoholic beverages. It is a volatile, flammable, colorless liquid that acts as a central nervous system depressant. Ethanol can impair different types of memory.

College drinking is the consumption of alcohol by students on the campus of any college or university. The age at which it is legal to drink varies by country and affects whether college drinking is considered illegal (e.g., as in the United States, where it is illegal for those under the age of 21 to drink).

The short-term effects of alcohol (also known formally as ethanol) consumption–due to drinking beer, wine, distilled spirits or other alcoholic beverages–range from a decrease in anxiety and motor skills and euphoria at lower doses to intoxication (drunkenness), stupor, unconsciousness, anterograde amnesia (memory "blackouts"), and central nervous system depression at higher doses. Cell membranes are highly permeable to alcohol, so once alcohol is in the bloodstream it can diffuse into nearly every cell in the body.

The concentration of alcohol in blood is measured via blood alcohol content (BAC). The amount and circumstances of consumption play a large part in determining the extent of intoxication; for example, eating a heavy meal before alcohol consumption causes alcohol to absorb more slowly. The amount of alcohol consumed largely determines the extent of hangovers, although hydration also plays a role. After excessive drinking, stupor and unconsciousness can occur. Extreme levels of consumption can lead to alcohol poisoning and death (a concentration in the blood stream of 0.40% will kill half of those affected). Alcohol may also cause death indirectly, by asphyxiation from vomit.

Alcohol can greatly exacerbate sleep problems. During abstinence, residual disruptions in sleep regularity and sleep patterns are the greatest predictors of relapse.

In the early stages, patients with ALD exhibits subtle and often no abnormal physical findings. It is usually not until development of advanced liver disease that stigmata of chronic liver disease become apparent. Early ALD is usually discovered during routine health examinations when liver enzyme levels are found to be elevated. These usually reflect alcoholic hepatic steatosis. Microvesicular and macrovesicular steatosis with inflammation are seen in liver biopsy specimens. These histologic features of ALD are indistinguishable from those of nonalcoholic fatty liver disease. Steatosis usually resolves after discontinuation of alcohol use. Continuation of alcohol use will result in a higher risk of progression of liver disease and cirrhosis. In patients with acute alcoholic hepatitis, clinical manifestations include fever, jaundice, hepatomegaly, and possible hepatic decompensation with hepatic encephalopathy, variceal bleeding, and ascites accumulation.Tender hepatomegaly may be present, but abdominal pain is unusual. Occasionally, the patient may be asymptomatic.

In people with alcoholic hepatitis, the serum aspartate aminotransferase (AST) to alanine aminotransferase (ALT) ratio is greater than 2:1.AST and ALT levels are almost always less than 500. The elevated AST to ALT ratio is due to deficiency of pyridoxal-6-phosphate, which is required in the ALT enzyme synthetic pathway. Furthermore, alcohol metabolite–induced injury of hepatic mitochondria results in AST isoenzyme release. Other laboratory findings include red blood cell macrocytosis (mean corpuscular volume > 100) and elevations of serum γ-glutamyl transferase, alkaline phosphatase, and bilirubin levels. Folate level is reduced in alcoholic patients due to decreased intestinal absorption, increased bone marrow requirement for folate in the presence of alcohol, and increased urinary loss.The magnitude of leukocytosis reflects severity of liver injury. Histologic features include Mallory bodies, giant mitochondria, hepatocyte necrosis, and neutrophil infiltration at the perivenular area. Mallory bodies, which are also present in other liver diseases, are condensations of cytokeratin components in the hepatocyte cytoplasm and do not contribute to liver injury.Up to 70% of patients with moderate to severe alcoholic hepatitis already have cirrhosis identifiable on biopsy examination at the time of diagnosis.

Binge drinking occurs when students drink large amounts of alcohol in a relatively short space of time in order to feel the full effects of alcohol consumption. The National Institute of Alcohol Abuse and Alcoholism defines binge drinking as a pattern of drinking that brings a person's blood alcohol concentration, also known as BAC, to 0.08 grams percent or above. This is usually seen when men consume five or more drinks, and when women consume four or more drinks in a two-hour time period.

Young adults who participate in binge drinking experience higher rates of physical and sexual assault, and unwanted, unplanned, and unprotected sexual activity. There are also links between heavy alcohol consumption and depression.

The motivations among young students have changed as well. In recent years, more students are drinking with the intended purpose of getting drunk.