Hangover Symptoms: Causes, Remedies & When to See a Doctor

Hangover symptoms are the unpleasant physical and mental effects that follow a night of heavy drinking, and most Canadians have experienced them at some point — the throbbing headache, the waves of nausea, and the crushing fatigue. Understanding what triggers these symptoms and how to manage them can help you make smarter decisions about alcohol and know when to seek medical care.

What Are the Most Common Hangover Symptoms?

While the hangover causes behind your misery involve dehydration, inflammation, and disrupted sleep, the severity varies from person to person. There is no guaranteed safe amount of alcohol that will prevent a hangover. This guide covers everything Canadian readers need to know, from effective remedies to warning signs that mean it is time to visit your family doctor or a walk-in clinic.

What Is a Hangover?

Common Hangover Symptoms: Severity and What They Mean

Hangover Symptom	Description	Severity	Typical Duration
Headache	Throbbing or pounding pain caused by dehydration, blood vessel dilation, and acetaldehyde buildup in the bloodstream	Mild to Severe	4–12 hours
Nausea and Vomiting	Stomach irritation from alcohol’s effect on the gastrointestinal lining and increased stomach acid production	Mild to Severe	2–8 hours
Fatigue and Weakness	Disrupted sleep cycles, low blood sugar, and the body’s effort to metabolize alcohol deplete energy reserves	Mild to Moderate	6–24 hours
Increased Sensitivity to Light and Sound	Neurological overstimulation caused by alcohol’s rebound effect on the central nervous system after sedation	Mild to Moderate	4–10 hours
Increased Heart Rate (Tachycardia)	Alcohol causes blood vessel changes and dehydration that can elevate resting heart rate during recovery	Mild to Moderate	2–6 hours
Anxiety and Irritability	Known as “hangxiety,” caused by alcohol’s suppression of GABA receptors rebounding, increasing nervous system activity	Mild to Severe	8–24 hours

A hangover is your body’s reaction to drinking too much alcohol. Symptoms typically appear the morning after heavy drinking, when your blood alcohol level drops significantly. The worse the drinking session, the worse the hangover tends to be.

However, there is no set amount of alcohol that will guarantee you avoid a hangover. Every person’s body processes alcohol differently. As a general rule, drinking more always increases your risk.

The good news is that a hangover almost always goes away on its own. In some cases, though, symptoms can last longer than 24 hours. The only truly effective way to prevent a hangover is to drink responsibly — or not at all.

Common Hangover Symptoms

Hangover symptoms can range from mildly annoying to seriously uncomfortable. They usually peak when your blood alcohol concentration returns to zero — often in the early morning hours.

Depending on how much and what you drank, you may experience some or all of the following:

• Fatigue and weakness
• Headache and muscle aches
• Intense thirst
• Dizziness, nausea, or vomiting
• Stomach pain
• Poor or disrupted sleep
• Sensitivity to light
• Sensitivity to loud sounds
• Rapid heartbeat
• Red or bloodshot eyes
• Trembling or shakiness
• Difficulty concentrating
• Anxiety, low mood, or irritability

These symptoms can affect your ability to work, drive, or care for others. In addition, irritability and poor concentration can strain relationships and reduce your performance at work or school.

How Long Does a Hangover Last?

Most hangovers resolve within 12 to 24 hours. However, some people feel the effects for longer, depending on how much they drank and their overall health. Older adults may find hangovers last longer than they did when they were younger.

What Causes a Hangover?

A hangover is not caused by just one thing. Several processes happen in your body at the same time when you drink too much alcohol. Together, they produce the miserable symptoms you feel the next day.

Dehydration

Alcohol causes your kidneys to produce more urine than usual. As a result, your body loses more fluid than it takes in. This dehydration is responsible for symptoms like thirst, dizziness, and headache.

Inflammation

Alcohol triggers an inflammatory response from your immune system. This inflammation can cause difficulty concentrating, memory problems, loss of appetite, and a general feeling of being unwell.

Stomach Irritation

Alcohol irritates the lining of your stomach. It also increases acid production and slows down how quickly your stomach empties. Therefore, nausea, vomiting, and stomach pain are common hangover complaints.

Low Blood Sugar

Drinking alcohol can cause your blood sugar levels to drop. When blood sugar gets too low, you may feel tired, shaky, weak, and moody. Eating a proper meal before or while drinking can help reduce this effect.

Disrupted Sleep

Alcohol may make you feel sleepy, but it actually lowers the quality of your sleep. You are likely to wake up more often and miss out on deep, restful sleep. This poor sleep makes fatigue and dizziness worse the next morning.

Blood Vessel Expansion

Alcohol causes your blood vessels to widen. This expansion is a major cause of the pounding headache that many people experience during a hangover.

Congeners

Many alcoholic drinks contain substances called congeners. These are chemical by-products formed during fermentation that give drinks their flavour and colour. Darker drinks like whiskey, bourbon, and cognac contain more congeners than clear spirits like vodka or gin. Furthermore, drinks with more congeners tend to cause worse hangovers.

For more information on how alcohol affects the body, visit Health Canada’s alcohol information page.

Hangover Risk Factors

Anyone who drinks too much can get a hangover. However, some people are more likely to experience one than others. Knowing your risk factors can help you make better decisions about drinking.

The following factors can increase your risk of a hangover:

• Drinking on an empty stomach: Food slows alcohol absorption. Eating before or while drinking reduces how quickly alcohol enters your bloodstream.
• Smoking while drinking: Combining nicotine and alcohol appears to make hangovers worse. The two substances can amplify each other’s negative effects.
• Not sleeping enough after drinking: Some hangover symptoms are partly caused by poor sleep. Going to bed at a reasonable time can reduce how bad you feel the next day.
• Family history of alcohol problems: If close relatives have struggled with alcohol use, you may have an inherited difference in how your body processes alcohol. This can affect your hangover risk.
• Genetics: Some people carry genes that cause them to flush, sweat, or feel ill after even small amounts of alcohol. This is especially common in some East Asian populations.
• Drinking darker spirits or coloured drinks: As mentioned, drinks with more congeners tend to cause worse hangovers.

Interestingly, research suggests that people who drink frequently may develop some tolerance to hangovers. However, this does not mean frequent drinking is safe — heavy alcohol use carries serious long-term health risks.

According to the Mayo Clinic’s hangover overview, there is no reliable way to prevent a hangover other than drinking less or not at all.

When to See a Doctor

A typical hangover goes away on its own and does not require medical attention. However, you should speak with your family doctor or visit a walk-in clinic if hangovers are regularly affecting your quality of life. Repeated heavy drinking is a serious health concern, and many effective treatments are available through your provincial health plan.

Signs of Alcohol Poisoning — Call 911 Immediately

A severe hangover can sometimes be confused with alcohol poisoning, which is a medical emergency. Alcohol poisoning can be life-threatening and requires immediate care.

Call 911 right away if someone who has been drinking shows any of these signs:

• Confusion or unresponsiveness
• Persistent vomiting
• Seizures
• Fewer than eight breaths per minute
• Irregular breathing
• Blue-tinged or pale skin
• Low body temperature (hypothermia)
• Loss of consciousness or fainting

Do not leave someone alone if you suspect alcohol poisoning. Turn them on their side to prevent choking and stay with them until emergency help arrives.

If you are concerned about your own drinking or someone else’s, the World Health Organization’s alcohol fact sheet offers reliable guidance on alcohol-related harm.

Hangover Remedies: What Actually Helps

There is no magic cure for a hangover. Despite what you may have heard, most popular remedies do not have strong scientific support. However, some simple steps can help ease your symptoms while your body recovers.

Stay Hydrated

Drinking water or an electrolyte drink can help replace fluids lost to alcohol’s diuretic effect. Sip water steadily rather than drinking large amounts all at once.

Eat Something

A light, easy-to-digest meal can help raise your blood sugar and settle your stomach. Toast, crackers, or bananas are good choices. Avoid greasy or heavy foods if you feel nauseous.

Rest

Your body needs time to recover. Rest as much as you can. If you had a poor night’s sleep, try to nap or take it easy during the day.

Pain Relievers — With Caution

Over-the-counter pain relievers like ibuprofen or aspirin may help with headache and muscle aches. However, avoid acetaminophen (Tylenol) if you have been drinking heavily, as combining it with alcohol can cause liver damage. Always follow the dosing instructions on the label and check with a pharmacist if you are unsure.

Avoid “Hair of the Dog”

Drinking more alcohol to cure a hangover is not a safe or effective strategy. It simply delays symptoms and can contribute to unhealthy drinking patterns over time.

Responsible Drinking in Canada

Canada’s guidance on alcohol consumption has become more cautious in recent years. Health Canada and other authorities now recommend limiting alcohol intake significantly to protect long-term health. Any amount of alcohol carries some health risk.

If you are concerned about how much you or someone you care about is drinking, talk to your family doctor. They can connect you with support programmes available through your province, many of which are covered under provincial health plans at no cost to you. Walk-in clinics can also be a good first step if you do not have a regular family doctor.

Key Takeaways

• A hangover is a collection of unpleasant symptoms caused by drinking too much alcohol.
• Common symptoms include headache, nausea, fatigue, thirst, and anxiety.
• Hangovers are caused by dehydration, inflammation, low blood sugar, stomach irritation, poor sleep, and congeners in alcoholic drinks.
• Most hangovers resolve within 24 hours on their own.
• There is no proven cure — rest, water, and light food are your best options.
• Call 911 immediately if someone shows signs of alcohol poisoning.
• If hangovers are a regular problem, speak with your family doctor or visit a walk-in clinic.
• The only reliable way to prevent a hangover is to drink less or not at all.

According to Mayo Clinic’s guide to hangover symptoms and causes, this information is supported by current medical research.

For more information, read our guide on hormonal conditions like Cushing’s syndrome that can mimic fatigue and nausea.

This article is for general information purposes only and is not a substitute for professional medical advice. Always consult your family doctor or a qualified healthcare provider if you have concerns about your health or alcohol use.