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Alcohol Intoxication Symptoms and Signs

Alcohol is a depressant.

Alcohol is a depressant of the central nervous system, so it inhibits certain brain functions, such as muscle coordination or ability to concentrate [44]. Alcohol is not a stimulant. If you are sleepy, alcohol will make you more sleepy; if you are tired, alcohol will make you more tired [36].

Symptoms of Alcohol Intoxication

Within as few as 10 minutes after a single alcoholic drink, you may feel more relaxed and less anxious [1]. By continuing drinking, the increasing blood alcohol concentration (BAC) may affect your attention, memory and judgement; other typical symptoms include blurred vision, slurred speech, unsteady gait, impaired coordination and sleepiness. At even higher BACs you may fall in coma or even die.

Chart 1. Alcohol Effects at Certain BAC*


Psychological Effects

Physical Effects

0.01-0.03 Slight relaxation, loss of shyness Slight lightheadedness and sleepiness; decreased ability to perform 2 tasks at the same time (lowered divided attention)
0.04-0.06 “Buzz”, mild euphoria, feeling of warmth and well being, talkativeness, self-confidence, showing off; slightly impaired judgement, memory and self-control Slightly reduced balance and lower ability to focus eyes and track moving objects, slower response to driving emergencies (prolonged reaction time)
0.05 Legal drink driving limit in Australia and many European countries
0.07-0.09 Euphoria, impaired judgement, self-control and memory; persons of the opposite sex seem to be more attractive (“beer goggles”). Impaired balance, coordination, fine motor skills and speech, reduced visual acuity and hearing, impaired estimation of driving speed and distance
0.08 Legal drink driving limit in Canada, United Kingdom and United States
0.10-0.125 Feeling “high,” increased sexual desire, but lower sexual performance Unsteady gait, slurred speech, blurred vision, difficulty maintaining lane position when driving
0.13-0.15 Feeling of unease; blackouts (loss of memory for the events during drinking) Impaired fine motor skills (writing, putting a key in the lock); vomiting
0.16-0.20 Anxiety, restlessness, mood swings, complaining, overly friendly or aggressive behavior “Sloppy drunk” appearance with swaying, bobbing head and sleepy, glassy eyes
0.21-0.30 Depression, apathy, gross mental confusion, disorientation The need for assistance in walking; reduced or absent sensitivity to pain (anesthesia), stupor (responsiveness only to deep pinch or face slapping); impaired temperature regulation (danger of hypothermia or hyperthermia)
0.31-0.40 Violence (in some individuals) Deep snoring. Loss of bladder and bowel control, decreased breathing and heart rate, passing out, possible death. Above 0.35, possible complete absence of feelings to touch (surgical level anesthesia).
0.41 or greater Coma, low blood pressure, irregular breathing; possible death due to a respiratory depression.

*BAC = blood alcohol concentration; Chart 1 sources: [22,23,24,25,26,27] NOTE: Different people may experience various symptoms of alcohol intoxication at very different BACs [22].

Disinhibition and Alcohol Myopia

Typical alcohol effects, such as increased self-confidence, talkativeness, self-disclosure, euphoria, expressing sexual desire, aggression and risky behavior are not caused by brain stimulation, but rather by the inhibition of your learned inhibitions, so by disinhibition [2,3]. Alcohol does not always cause disinhibition, though. For example, when someone clearly reminds you about the dangers of your behavior, your may become even more inhibited about that behavior than when you are sober [2].

Alcohol intoxication may limit your attention to what is in front of you, leaving your long-term problems and moral norms behind [4,5]. This is called alcohol myopia or nearsightedness. Alcohol does not have a specific effect on mood, but it tends to enhance your current mood: when you are happy or in a happy environment, drinking may make you happier, and when you are worried, drinking may make you more worried, especially when you drink alone and do nothing.

Alcohol consumption in combination with a distracting activity that requires some mental effort, for example study or serous conversation, may reduce anxiousness or depression [6].

Signs of Alcohol Intoxication

Eyes and Vision

A person who has been drinking may have difficulty to focus eyes on the moving objects, impaired depth perception, peripheral vision, contrast sensitivity and glare recovery (at BACs above 0.05 g/100 mL) [7,8], blurred vision, limited night and color vision (at BACs above 0.1) [9,10], double vision (at BACs above 0.2) [9] and limited peripheral vision (tunnel vision) [29].

Lateral phoria. A person who has drunk as little as 3 standard drinks may see objects farther to the right or left from their actual position [12].

Glassy eyes may be observed in individuals with BACs above 0.15 g/100 mL.

Bloodshot eyesred appearance of the eye whites due to blood vessels dilation–are a common but nonspecific sign of alcohol intoxication [13]. Chronic alcoholics may have bloodshot eyes when intoxicated or not; it may take several weeks after stopping drinking for their eyes to clear up.

A person with BAC above 0.1 g/100 mL blood will likely have horizontal gaze nystagmus – involuntary jerky eye movements as observed during a field sobriety test [15].

Dilated pupils may be observed in a severely intoxicated comatose persons [14].


Individuals with BACs above 0.08 g/100 mL blood may have decreased hearing ability, especially in the range of speech frequencies (~1000 Hz) [16].

Alcohol and Sleep

One drink before bed may increase the total sleeping time in healthy individuals, but more drinks may decrease it [37].

Both light and heavy drinking before bed, or even moderate drinking for up to six hours before bed, may initially help you fall asleep quicker and make the first few hours of sleep deeper, but heavy drinking may disturb sleep in the second half of the night, probably due to rebound excitation when blood alcohol concentration falls [38,39].

During alcohol withdrawal, insomnia and sleep disturbances are common [29]. Individuals with severe delirium tremens after alcohol withdrawal may fail to fall asleep for several days [30]. Heavy drinkers may drink before bed to prevent insomnia due to alcohol withdrawal, but they still often report insomnia [40]. Some alcoholics experiencing protracted withdrawal syndrome may have sleep disturbances lasting for several weeks or even more than a year [39,44].

In one 1999 study, insomniacs having 2 drinks before bed had improved quality of sleep during the whole night [43].

A single alcohol drink may increase daytime sleepiness and decrease driving ability [42].

Alcohol may aggravate sleep apnea (interruption of breathing for 10 seconds or more during sleep). Sleep apnea is more common in alcoholics than in non-alcoholics and may worsen with age [39,41].

Alcohol relaxes throat muscles and increases the possibility of snoring after evening drinking [39].

Muscles and Exercise Performance

Acute alcohol ingestion does not improve physical performance; it may actually reduce muscle strength and endurance [17,19]. Binge alcohol drinking inhibits the synthesis of proteins and may thus reduce the muscle-growing (anabolic) effect of protein intake and exercise [45].

Alcohol prolongs the reaction time, impairs balance and accuracy of movements [22,23].

Lying in the same position after severe alcohol intoxication with prolonged compression of the limb may result in skeletal muscle disintegration (alcoholic myopathy or rhabdomyolysis) with severe pain, weakness and swelling of the affected limb and dark urine; symptoms may develop over hours or few days and resolve within a week of abstention [18,20,21].

Personal Factors and Alcohol Effects

A person who is not used to drinking may get drunk after much smaller amount of alcohol then a regular drinker of the same body weight who has developed some tolerance to alcohol.

Women tend to be more affected by the same amount of alcohol than men of the same body weight, probably due to greater percent of body fat, in which alcohol is poorly soluble, so more alcohol stays in their blood than in men [35]. In general, women tend to be more aggressive after drinking and are involved in more alcohol-related troubles, such as car accidents, than men [35].

Psychologically sensitive and physically weak persons may be more affected by alcohol than the robust ones.

The expectation about the alcohol effects may have greater effect on your behavior than the alcohol itself. In one study, participants who were drinking non-alcoholic beverages (tonic water), but were told they were drinking gin tonic, experienced decreased anxiety, increased sexual arousal and aggressiveness [30]. In another study, participants who were drinking only tonic water, but were thinking they were drinking tonic water with vodka, were more susceptible for misleading information than participants who were drinking the same tonic water and were told so [31].

Alcohol’s Biphasic Effect

At the beginning of the drinking, as long as your blood alcohol concentration (BAC) is increasing from zero to 0.05-0.06 g/100 ml, you may experience a pleasant “buzz” effect of alcohol, increased energy and well being. After your BAC passes 0.06 g/100 mL, pleasant effects may start to vanish and unpleasant effects, such as an impaired balance, slurred speech, blurred vision and nausea may start to increase. This reversal of feelings during continuing drinking is called biphasic effect of alcohol [7]. When you start to feel bad during drinking, you can not expect to feel better by continuing drinking [7].

Alcohol and Dehydration

Within the first 3 hours of consumption, alcohol inhibits the release of the antidiuretic hormone (ADH) and thus increases the urine excretion, but it later stimulates ADH secretion and thus promotes water retention [32-p.134].

In one study, participants after drinking 1 liter of regular beer containing 4% of alcohol (4% abv) excreted only 150 mL of urine more than after drinking 1 liter of non-alcoholic beer. When the participants were dehydrated when they started to drink, they excreted about the equal amounts of urine both after alcoholic and non-alcoholic beer [33].

Dehydration in alcohol-poisoned persons is not very common and is probably more often caused by alcohol-related vomiting and diarrhea rather by the direct effect of alcohol on the urine excretion [34-p.392].

In summary, alcohol by itself probably does not cause significant dehydration [32-p.134].

Conditions That May Mimic Alcohol Intoxication (Differential Diagnosis)

Euphoria can appear in the exciting, manic phase of the bipolar disorder, and after ecstasy, cocaine or methamphetamine use.

Strange behavior can be due to attention deficit hyperactivity disorder (ADHD), panic attack, hypnosis, Lyme disease, brain tumor, schizophrenia, dementia or ecstasy use.

Nausea or vomiting can result from food poisoning, infectious diseases, gastritis, morning sickness during pregnancy, motion sickness, bulimia, hepatitis, pancreatitis, advanced cancer, chemotherapy, antibiotics, such as metronidazole, or other medications.

Drowsiness or apathy can be due to lack of sleep, sleep apnea, dehydration, depression, liver disease, kidney failure, antihistamines, antidepressants, sleeping pills, barbiturates, morphine, anesthetics, heroin or methadone.

Dizziness can be caused by hypoglycemia, anemia, low blood pressure, vertigo due to inner ear disorders or multiple sclerosis.

Trouble walking can be a symptom of peripheral neuropathy (in long-term drinkers and diabetics), stroke, multiple sclerosis or cerebral palsy.

Falling on the ground and impaired consciousness can occur due to fainting (from fear, pain, heat, severe dehydration, irregular heart rhythm), epileptic attack, hypoglycemia or ketoacidosis in diabetics, kidney failure, liver failure (hepatic encephalopathy with hyperammonemia in heavy drinkers), electrolyte imbalance (hyponatremia, hypernatremia), severe allergic reaction, head injury, stroke, CO2 poisoning, poisoning with methanol, ethylene glycol, suicide attempt by drugs or exhaust gases.

A combination of the above symptoms can appear in hypophosphatemia, vitamin B6 deficiency, mountain sickness, lithium (used in bipolar disorder), inhaling nitrous oxide (laughing gas), ether, gasoline, paint thinners, glue or nail polish remover (acetone).

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