What is alcohol hangover

Hangovers are a frequent, unpleasant experience among people who drink to intoxication. An alcohol hangover (also called veisalgia) refers to the mental, emotional and physical symptoms which an individual experiences after they have consumed alcohol. A hangover occurs when the person has recovered from the intoxicating effects of alcohol – that is, when the body has metabolized or processed the alcohol consumed and is sober. People usually suffer from a hangover the morning after they consumed alcohol. Sometimes, however, the person will still be intoxicated when they wake up and will not experience a hangover until they are sober again. Alcohol hangover is characterized by headache, tremulousness, nausea, diarrhea, and fatigue combined with decreased occupational, cognitive, or visual–spatial skill performance ¹⁾. Other symptoms of hangover in varying combinations may include lightheadedness, impaired memory and concentration difficulties. It’s important to be aware that you may not be fit to drive a car or operate machinery while you have a hangover, as you are likely to be drowsy or have difficulty concentrating.

A hangover is also a good sign that you drank too much – that is, you’ve consumed so much alcohol that it might present health risks, including damaging your brain. It’s not surprising that people who report a greater number of hangovers show damage to brain structures.

The symptoms of a hangover seem to be due to a combination of ethanol’s main metabolic product acetaldehyde, congeners including methanol, endocrine and immune system disturbances, dehydration, and sleep disturbance ²⁾. Substantially increased risks of all cause mortality can occur even in people drinking less than recommended maximums, particularly among younger adults. An increased risk of strokes has been observed in young adults, particularly on occasions when alcohol intake is higher than average ³⁾. In addition, during celebrations at Christmas, for instance, alcohol consumption increases and may lead to a rise in fatal alcohol poisonings by 0.4% for every 1% increase in the sales of spirits ⁴⁾.

Patients with hangover may pose substantial risk to themselves and others despite having a normal blood alcohol level. Hangover may also be an independent risk factor for cardiac death.

Despite the prevalence of hangovers, however, this condition is not well understood scientifically. In the workplace, a person with a hangover may experience impaired memory and visual-spatial skills ⁵⁾.

Hangovers and the workplace

In addition to the unpleasant physical, mental and emotional symptoms, hangovers are associated with diminished workplace performance and poorer grades. In particular, the effects of a hangover have been found to impair the workplace performance of pilots, drivers, skiers and managers.

In the United States, related absenteeism and poor job performance cost $148 billion annually (average annual cost per working adult, $2000) ⁶⁾. Although hangover is associated with alcoholism, most of its cost is incurred by the light-to-moderate drinker. Patients with hangover may pose substantial risk to themselves and others despite having a normal blood alcohol level.

Regardless of occupation, people who have a hangover are more likely to:

• Be late;
• Have an accident at work: This is especially dangerous for people who deal with machinery and other safety-sensitive operations;
• Be absent from work;
• Have lower morale while at work;
• Perform their work poorly; and
• Have disputes with peers and/or colleagues.

Not only does this affect the individual and their colleagues, but it also affects the business and the country’s economy as a whole.

Multiple possible contributors to the hangover state have been investigated, and researchers have produced evidence that alcohol can directly promote hangover symptoms through its effects on urine production, the gastrointestinal tract, blood sugar concentrations, sleep patterns, and biological rhythms. In addition, researchers postulate that effects related to alcohol’s absence after a drinking bout (i.e., withdrawal), alcohol metabolism, and other factors (e.g., biologically active, nonalcohol compounds in beverages; the use of other drugs; certain personality traits; and a family history of alcoholism) also may contribute to the hangover condition. Few of the treatments commonly described for hangover have undergone scientific evaluation.

How long does a hangover last

Anyone who has experienced a hangover would probably describe it as an unpleasant experience. It can last anywhere between 8 and 24 hours, and disrupt daily tasks and responsibilities such as going to work, looking after kids or enjoying time with friends and family.

Which ingredients in an alcoholic beverage cause a hangover?

Ethanol is alcohol, or the ingredient in alcoholic beverages that causes intoxication. However, it is not known whether alcohol plays a direct role in causing a hangover, or whether other ingredients or side effects of drinking alcohol cause the hangover. There are other chemicals contained in alcoholic drinks that are believed to play a role in the development of a hangover, in particular congeners.

What are congeners?

Congeners are biologically active chemicals (chemicals which exert an effect on the body or brain) and are often contained in alcoholic beverages, in addition to ethanol, the key biologically active ingredient of alcohol.

Congeners are produced in the process of fermentation or ageing, when organic chemicals (chemicals from plants) in the beverage break down. They may also be added during the production process to contribute to the taste, smell and appearance of the beverage.

Types of congeners

Many different types of congeners can be found in various alcoholic beverages.

• Furfural

Furfural is a congener that inhibits yeast metabolism. It may be added to alcoholic beverages during the fermentation stage.

• Tannins

Tannins are congeners found in wine. Tannins contain powerful antioxidants such as polyphenols.

• Fusel oil

Fusel oil is a congener produced in the process of alcoholic spirit distillation. The name is derived from the German word fusel, which means ‘bad liquor’. In high concentrations, it causes an off flavor. In low concentrations, fusel oil adds to the flavors and aromas of alcoholic beverages.

• Acetaldehyde

Acetaldehyde is a toxic congener produced by the breakdown of ethanol.

• Methanol

Methanol is a congener contained in alcoholic beverages which is thought to contribute to hangover symptoms. When metabolized, methanol breaks down into formaldehyde and formic acid. The elimination of methanol from the body coincides with the onset of a hangover. People who metabolise methanol faster than others will feel greater physical symptoms of a hangover. Whiskey, red wine, brandy and other dark spirits contain the greatest volume of methanol, and have been suggested to cause worse hangovers, although this is yet to be confirmed.

Beverage congener content

Alcoholic beverages with a high congener content appear to cause more severe hangovers than those with a low congener content. One study reported that individuals who became intoxicated drinking bourbon reported more severe hangovers the following day than individuals who became intoxicated drinking vodka ⁷⁾. However, there were no differences between a bourbon and vodka drinker on mental tests performed the following day.

Another study found a lower prevalence of hangover in participants drinking low congener alcohols (white wine, gin, vodka, pure ethanol) compared to participants who drank high congener alcohols (e.g. brandy, whiskey and red wine).

Effects of congeners

Congeners are primarily contained in darker liquors, brandy, tequila, whiskey and wine. The clear liquors, including white rum, vodka and gin, tend to cause hangover less frequently and are preferred by people who have alcohol dependence.

For example, bourbon has almost 40 times the quantity of congeners that is contained in vodka and has been reported to have a greater intoxication effect, though this has not been confirmed. Bourbon is believed to increase the chance of a hangover more than beverages containing fewer congeners. Studies have also found an association between greater drowsiness the next day and bourbon consumption.

Are hangovers more likely with some types of alcohol?

There have been studies conducted to investigate whether different types of alcohol are more or less likely to cause a hangover or affect the severity of a hangover. Many scientists believe that the greater the congener content in the alcohol, the worse the hangover will be. While drinks with more congener content may increase the perceived intensity of a hangover, there is no evidence to suggest that they worsen next-day performance, sleep or thinking ability. These results suggest that a glass of champagne, or a glass of red wine with the same alcohol content, are equally likely to cause a hangover. However, you may feel worse after drinking red wine.

Headaches are more commonly experienced after red wine than white wine. The former is thought to increase serotonin and histamine levels more than the latter; the reason for this is unknown.

Who gets a hangover?

Hangovers are a common side effect of drinking to intoxication. People who drink heavily more often are more likely to experience hangovers. The more intoxicated one becomes, the more severe a hangover is likely to be. For example, one study reported that the greater the concentration of alcohol in a person’s body, the more severe their hangover. Peak alcohol concentration refers to the highest concentration alcohol reaches in your body body when you are intoxicated. It is believed to be a better predictor of hangover than the overall amount of alcohol consumed, adjusted to take into consideration your body weight. Hangovers also become more likely the longer the duration of alcohol consumption.

As such, the prevalence of hangovers is expected to be higher in populations that drink more heavily, including:

• Stressed people: The more stressed a person, the more likely they are to drink larger quantities of alcohol;
• Men: Men are more likely than women to consume intoxicating quantities of alcohol; and
• Youth: Young people tend to binge drink more than their older counterparts.

However, not all people experience a hangover after moderate levels of alcohol consumption, and peak alcohol concentration does not reliably predict whether someone will experience a hangover. For example, one study reported that 76% of participants experienced a hangover the morning after moderate drinking (defined as a quantity of alcohol which caused their alcohol concentration to rise to 0.115 g%, much higher than the .05 level acceptable for driving). Other studies have reported 25–50% of participants did not experience a hangover after intoxication. Interestingly, a study on a group of people with alcohol dependence (alcoholism) determined that 50% of the participants had not experienced a hangover in the previous year.

Biological differences

Biological differences (e.g. physical and mental differences) which affect an individual’s response to alcohol might also affect the incidence and severity of hangover. These include:

• Personality and temperament: Some aspects of personality or temperament have been reported to affect the likelihood of hangover, including personality traits such as neuroticism, anger and defensiveness;
• Family history of alcoholism and other risk factors for alcohol dependence: Has been found to increase the likelihood and severity of hangover. The reasons for this are not well understood, although some researchers believe it is because individuals at greater risk of alcohol dependence may experience more acute hangover symptoms and drink further alcohol to treat such symptoms, and in doing so increase their chances of developing alcohol dependence; and
• Metabolism.

Metabolism of methanol

The rate at which an individual metabolizes methanol (a congener commonly found in alcoholic drinks which produces formic acid and formaldehyde when it is broken down in the body) is thought to influence the experience of hangover. People who metabolize methanol more quickly are thought to experience more severe hangover symptoms. While no studies have examined methanol metabolism, evidence regarding the effects of methanol and the way in which it is broken down by the body support this hypothesis.

Drinks with a higher methanol content are associated with a greater likelihood of hangover, and hangover occurs at the same time the body begins metabolizing methanol. In addition, administering ethanol (alcohol), which stops methanol being broken down to formic acid and formaldehyde, reduces the symptoms of a hangover (note that this should not be used as a treatment).

Metabolism of ethanol

The production of toxic by-products occurs in ethanol metabolism. Acetaldehyde is one such metabolite which has toxic effects on the body in high concentrations. For most people, the acetaldehyde is quickly metabolized and has little time to cause toxic symptoms. However, slow metabolizers can retain acetaldehyde for longer and, because of this, may experience symptoms typical of a hangover such as:

• Rapid pulse;
• Sweating;
• Skin flushing;
• Nausea; and
• Vomiting.

Psychological factors

Psychological factors influence a person’s experience of hangover. Individuals with psychological problems report experiencing more severe hangovers after drinking to intoxication. These factors include:

• Guilt about alcohol consumption;
• Having a neurotic personality;
• Being angry or defensive;
• Becoming angry or depressed whilst intoxicated;
• Having experienced a negative life event; and
• Personality traits associated with a high risk for alcoholism.

These factors have been found in some studies to be more important determinants of hangover symptoms than the amount of alcohol consumed. As only 50–75% of people who drink alcohol to intoxication experience hangovers and many studies have shown no relationship between peak blood alcohol concentrations, these findings are plausible.

Gastrointestinal disturbances

Alcohol causes gastrointestinal disturbances such as:

• Irritation of stomach and intestines;
• Gastritis (inflammation of stomach lining);
• Increased production of gastric acid; and
• Increased production of intestinal secretions.

The gastrointestinal disturbances can cause abdominal pain, nausea and vomiting.

Diuretic effect of alcohol

Alcohol is a diuretic, which means it causes the body to expel more urine than usual. Consumption of four alcoholic drinks causes the elimination of 600-1,000 mL of urine. Alcohol affects the body’s hormone production system and reduces the effect of the anti-diuretic hormone which prevents the expulsion of urine by triggering the kidneys to reabsorb water. When the kidneys do not reabsorb water, the water is expelled and the person urinates more often.

Low blood sugar

A decrease in blood sugar levels is an effect of alcohol consumption. The by-products of alcohol can inhibit glucose production, especially after binge drinking.

Excessive alcohol consumption, particularly when it is coupled with poor nutritional intake, can lead to hypoglycaemia (low blood glucose levels). The resulting hangover effects include weakness, fatigue and mood disturbances.

Alcohol withdrawal

Hangovers are thought to affect the brain in a similar way to alcohol withdrawal, which is the experience an alcoholic has if they do not consume alcohol. The symptoms of both hangovers and alcohol withdrawal are alleviated if the person is given more alcohol.

Scientists believe that the body compensates for alcohol’s sedative effect by changing the way the brain responds, making it more responsive to excitatory stimuli and less responsive to stimuli which usually have an inhibitory effect. Effectively, the brain copes with alcohol by becoming hyper-excited. Once alcohol has been eliminated from the system, the brain remains in a hyper-excited state which induces tremor, sweating and rapid heartbeat.

Sleep deprivation

Sleep deprivation is a major contributing factor to a hangover and as such correlates significantly with emotional, mental and physical symptoms.

Hormones that control the wake/sleep cycle (e.g. serotonin and glutamate) are affected by alcohol consumption. As the blood alcohol level (BAL) rises, an individual is more likely to stay awake. When the blood alcohol level (BAL) decreases, it causes a sedative or sleepy effect.

Alcohol decreases the time it takes to fall asleep, but disturbs the natural sleep cycle. In the first half of sleep when the alcohol is being processed or metabolized:

• The time spent in rapid eye movement (REM) or light sleep is greatly diminished; and
• The time spent in slow wave or deep sleep is increased.

In the second half of sleep when the alcohol has been processed or metabolized:

• The time spent in REM sleep is increased and sleep is lighter than usual;
• The individual will experience increased wakefulness or difficulty sleeping.

The specific effects of sleep deprivation are complex and will depend on the amount of alcohol consumed and the time between consumption and sleep onset. In general, it can be said that alcohol consumption is associated with lighter, less efficient and more disturbed sleep. This will usually have a negative effect on the individual’s mood and thinking the next day.

Other drugs

Using other drugs such as cocaine and tobacco while drinking may increase the severity of hangover, and some drugs may produce their own hangover effect. The associations between combining alcohol and drug use, and the presence or severity of a hangover, are poorly understood.

Hangover complications

When you have a hangover, you’re likely to experience problems with:

• Memory
• Concentration
• Dexterity

Not surprisingly, this temporary dulling of your abilities increases your risk of a number of problems at school or work, such as:

• Absenteeism
• Trouble completing tasks
• Conflict with others
• Falling asleep at school or on the job
• Workplace injuries.

Hangover symptoms

Hangovers produce a range of unpleasant physical, mental and emotional symptoms that combine to create an overall feeling of poor wellbeing. Each person will experience a hangover differently, but there are some common symptoms.

Physical symptoms

The physical symptoms of a hangover can include:

• Headache;
• Muscle soreness;
• Thirst;
• Sensitivity to light and sound;
• Drowsiness and fatigue;
• Nausea;
• Increased systolic blood pressure;
• Rapid heartbeat;
• Tremor;
• Sweating;
• Diarrhea;
• Loss of appetite; and
• Red eyes.

Mental symptoms

The mental symptoms of a hangover can include:

• Dizziness;
• Vertigo;
• Irritability;
• Changes to visual perception;
• Poor performance on identification tasks;
• Difficulty paying attention, staying alert, reacting and processing information;
• Reduced coordination, including hand–eye and limb coordination;
• Poor memory and recall; and
• Poor performance with task-driven activities.

Emotional symptoms

Some people will experience depression, anxiety and/or irritability when they have a hangover, and the more you consume, the more likely you are to experience these emotional symptoms.

However, emotional changes may be indirect effects of a hangover, caused not by the effects of alcohol itself, but by the physical and emotional symptoms of the hangover. For example, a study showed that a person’s mood deteriorates throughout the morning when they have a hangover, making them more prone to be depressed, anxious or irritable as the day wears on. As these disturbed moods only occur as the day progresses, not immediately when the person becomes sober, scientists believe that hangover symptoms such as headaches and difficulty remembering and processing information cause anxiety and depression, rather than the alcohol itself.

What causes a person to feel hungover?

Studies indicate that factors other than the quantity of alcohol consumed also influence whether a hangover is experienced. However, the causes of hangovers remain poorly understood. It is not clear whether a hangover is a direct effect of alcohol, the aftereffects of alcohol, or a combination of the two. Non-alcohol factors such as changes in sleep and eating patterns associated with alcohol intoxication may also play a role.

Various factors may contribute to a hangover. For example:

• Alcohol causes your body to produce more urine. In turn, urinating more than usual can lead to dehydration — often indicated by thirst, dizziness and lightheadedness.
• Alcohol triggers an inflammatory response from your immune system. Your immune system may trigger certain agents that commonly produce physical symptoms, such as an inability to concentrate, memory problems, decreased appetite and loss of interest in usual activities.
• Alcohol irritates the lining of your stomach. Alcohol increases the production of stomach acid and delays stomach emptying. Any of these factors can cause abdominal pain, nausea or vomiting.
• Alcohol can cause your blood sugar to fall. If your blood sugar dips too low, you may experience fatigue, weakness, shakiness, mood disturbances and even seizures.
• Alcohol causes your blood vessels to expand, which can lead to headaches.
• Alcohol can make you sleepy, but it prevents deeper stages of sleep and often causes awakening in the middle of the night. This may leave you groggy and tired.

Researchers have identified a number of factors which potentially play a role in hangovers and may make some people more susceptible to hangovers, including:

• Hormone changes due to increased acetaldehyde levels which occur with alcohol consumption, including changes to insulin production which impair glucose availability;
• Increased heart rate;
• Production of toxic by-products, which occurs when alcohol is metabolised or broken down. These products include acetaldehyde and acetate from the breakdown of ethanol, and formic acid and formaldehyde from the breakdown of methanol, a congener commonly found in alcoholic beverages;
• Increased blood flow to the brain;
• Alcohol triggers the release of neurotransmitters (e.g. histamine, serotonin and prostaglandins), which can cause headache;
• Disruption of body temperature: The body temperature is below normal during intoxication, and above normal during a hangover;
• Electrolyte imbalance and dehydration;
• Unaccustomed physical activity;
• Intermittent upper airway obstruction;
• Beverage congener content;
• Biological differences;
• Psychological state;
• Gastrointestinal disturbances;
• Diuretic effect of alcohol;
• Food deprivation and the corresponding low blood sugar level;
• Alcohol withdrawal;
• Sleep deprivation;
• Use of other drugs.

Risk factors for a hangover

Anyone who drinks alcohol can experience a hangover, but some people are more susceptible to hangovers than others are. A genetic variation that affects the way alcohol is metabolized may make some people flush, sweat or become ill after drinking even a small amount of alcohol.

Factors that may make a hangover more likely or severe include:

• Drinking on an empty stomach. Having no food in your stomach speeds the body’s absorption of alcohol.
• Using other drugs, such as nicotine, along with alcohol. Smoking combined with drinking appears to increase the likelihood of next-day misery.
• Not sleeping well or long enough after drinking. Some researchers believe that some hangover symptoms are often due, at least in part, to the poor-quality and short sleep cycle that typically follows a night of drinking.
• Having a family history of alcoholism. Having close relatives with a history of alcoholism may suggest an inherited problem with the way your body processes alcohol.
• Drinking darker colored alcoholic beverages. Darker colored drinks often contain a high volume of congeners and may be more likely to produce a hangover.

How to prevent a hangover

The best way of preventing a hangover is by avoiding intoxication – in other words, abstaining from alcohol. Hangovers can also be avoided by reducing the amount of alcohol that is consumed and drinking in moderation. Moderate alcohol use for healthy adults means up to one drink a day for women of all ages and men older than age 65, and up to two drinks a day for men age 65 and younger.

People who drink to intoxication may prevent a hangover or reduce the severity of their hangover by rehydrating and taking anti-inflammatory painkillers before sleeping. Avoiding alcoholic beverages with a lot of congeners (e.g. brandy, red wine and whiskey) may also reduce the perceived severity of experiencing a hangover.

Follow these tips to keep hangovers away:

• Don’t drink on an empty stomach. Before you go out, have a meal that includes carbohydrates (such as pasta or rice) or fats. The food will help slow down the body’s absorption of alcohol.
• Don’t drink dark-colored drinks if you’ve found that you’re sensitive to them. They contain natural chemicals called ‘congeners’ (impurities), which irritate blood vessels and tissue in the brain and can make a hangover worse.
• Drink water or non-sparkling soft drinks in between each alcoholic drink. Carbonated (sparkling) drinks speed up the absorption of alcohol into your system.
• Drink plenty of water before you go to sleep. Keep a glass of water by the bed to sip if you wake up during the night.
• Know your limits and only drink in moderation. Decide ahead of time how many drinks you’ll have — and stick to it. Don’t feel pressured to drink.
• Take it slow. Avoid having more than one alcoholic drink in an hour. Stop drinking completely when you’ve reached your limit (or before then).

Some people take over-the-counter pain relievers, such as aspirin or ibuprofen (Advil, Motrin IB, others), to prevent hangover symptoms. But ask your doctor if this is safe for you and what dosage is best for you. These medications may interact with other medications, and acetaminophen (Tylenol, others) may cause liver damage if too much alcohol is consumed.

How to cure a hangover

There are no real cures for hangovers, there are ways to ease the symptoms.

Treatment involves rehydrating your body so it can deal with the painful hangover symptoms (though the best time to rehydrate is before going to sleep).

Over-the-counter painkillers can help with headaches and muscle cramps. Paracetamol-based remedies are usually preferable, as aspirin may further irritate the stomach and increase nausea and sickness.

Sugary foods may help you feel less trembly. In some cases, an antacid may be needed to settle your stomach first.

Bouillon soup, a thin vegetable-based broth, is a good source of vitamins and minerals, which can top up depleted resources. Its main advantage is that it’s easy for a fragile stomach to digest.

You can replace lost fluids by drinking bland liquids that are easy on the digestive system, such as water, soda water and isotonic drinks (available in most shops).

‘Hair of the dog’ (drinking more alcohol) does not help. Drinking in the morning is a risky habit, and you may simply be delaying the appearance of symptoms until the alcohol wears off again.

If you’ve had a heavy drinking session, hangover or not, doctors advise that you wait 48 hours before drinking any more alcohol, in order to give your body tissues time to recover. Sometimes, of course, a hangover makes that advice easier to follow.

Hangover remedies

Testing the effectiveness of various ‘hangover cures’ has received little attention in the health profession. Some health professionals argue that finding a treatment is undesirable because hangovers act as a deterrent to intoxication. However, there is no evidence to suggest that the experience of a hangover deters a person from consuming alcohol, or that an effective hangover cure would lead to increased consumption.

Simple hangover cures

There are many measures which are commonly thought to reduce the intensity of hangover symptoms, but which have not been assessed in scientific studies. These include:

• Consuming fruit, fruit juice and other fructose- or glucose-containing foods (to date, the few studies which have examined the role of fructose have not shown any benefit in reducing hangover symptoms);
• Consuming complex carbohydrates to counteract low blood sugar levels;
• Antacids for gastrointestinal symptoms;
• Sleep to ease the fatigue;
• Consumption of non-alcoholic beverages for rehydration; and
• Caffeine to counteract fatigue and malaise.

If you have a headache or muscles aches, taking aspirin or another NSAID may help. However, be careful using these medicines if you are nauseous.

Research into hangover cures

A limited number of high quality scientific studies have been conducted to assess the effectiveness of various preparations in relieving hangover symptoms, some with positive results:

• In one study, taking γ linolenic acid from Borago officinalis (borage) the morning after intoxication reduced the overall hangover severity and the severity of headache, tiredness and laziness;
• A yeast preparation (250 mg dried yeast, 0.5 mg thiamine nitrate, 0.5 mg pyridoxine hydrochloride, and 0.5 mg riboflavin) was found to reduce symptoms of restlessness, impatience and discomfort in another study; and
• Tolfenamic acid, a prostaglandin inhibitor, has also been shown to reduce overall hangover symptoms and individual symptoms, including headache, nausea, vomiting, thirst, dry mouth, nervousness and tremor, compared to placebo.

However, these hangover remedies are not commercially available and further studies are needed to confirm that they are, in fact, effective.

Hair of the dog

It’s important not to drink more alcohol. While drinking more alcohol (a ‘hair of the dog’ drink) will temporarily relieve symptoms, it will increase toxicity in the long run and your symptoms may be worse when you sober-up again. Drinking to relieve the symptoms of a hangover can also lead to alcohol dependence.

Dietary supplements

Four trials tested dietary supplements: Borago officinalis (borage), Cynara scolymus (artichoke), Opuntia ficus-indica (prickly pear), and a yeast based preparation. Statistically significant differences were observed between the overall hangover symptom scores of groups in one trial using gamma-linolenic acid from borago officinalis (borage) and in another using a yeast-based preparation, when compared with placebo ⁸⁾. Specific reductions in headache, laziness and tiredness were observed in the former trial. In the yeast-based trial, specific reductions in discomfort, restlessness and impatience were observed. The other two trials (testing cynara scolymus and opuntia ficus-indica) did not report any statistically significant differences between the groups.

Another trial tested a combination preparation containing 250 mg dried yeast, 0.5 mg thiamine nitrate, 0.5 mg pyridoxine hydrochloride, and 0.5 mg riboflavin per tablet in participants who consumed vodka (40% volume alcohol) amounting to a total of 100 g absolute alcohol ⁹⁾. The difference in the change for the symptoms discomfort, restlessness, and impatience was statistically significant in favor of the yeast preparation. Two other trials that tested extracts of C scolymus and O ficus-indica reported no intergroup differences for their main outcome measures ¹⁰⁾.

Conventional agents

Four trials tested conventional agents: tropisetron, propranolol, tolfenamic acid, and fructose or glucose. A statistically significant difference was observed in the overall hangover symptom score between groups given tolfenamic acid in comparison with placebo. Specific reductions in headaches, nausea, vomiting, thirst, dry mouth, tremor and irritation were seen. The remaining trials (employing propranolol, tropisetron, and fructose or glucose) did not report any statistically significant differences between the groups. Three other trials, which tested propranolol, tropisetron, and fructose or glucose, reported no beneficial intergroup differences.

The study that evaluated tolfenamic acid reported swollen eyes and slight dysuria in two cases of those receiving the intervention.

Summary of hangover cures being sold over the internet

The paucity of randomized controlled trials is in stark contrast to the plethora of “hangover cures” marketed on the internet. This confirms the unreliability of the internet in healthcare matters. The findings of systematic review ¹¹⁾ show that no compelling evidence exists to suggest that any conventional or complementary intervention is effective for preventing or treating alcohol hangover. Encouraging findings for their main outcome measures exist for γ linolenic acid from B officinalis, a yeast based combination preparation, and tolfenamic acid. However, only single randomized controlled trials for each of the tested interventions were available, most were of small sample size, and all used unvalidated symptom scores. Independent replications of these studies are therefore necessary. The most effective way to avoid the symptoms of alcohol induced hangover is thus to practise abstinence or moderation.