Many people don't know that caffeine is a drug. It's a stimulant that's found in coffee, tea, energy drinks, some pain medicines, as well as in foods and drink.
Some common products with caffeine amounts are:
Other products that have caffeine include:
Caffeine can be used to treat some types of headaches, including migraines. Some pain medicines have caffeine. Your doctor or pharmacist can tell you if caffeine might work for you.
Less than 200 mg of caffeine (1 or 2 cups of coffee) can make you more alert, put you in a better mood, and make you feel less tired. It can also improve physical work and thinking. The effects usually start within half an hour and can last up to 12 hours.
Some people are sensitive to caffeine, and even small amounts can make them feel sick.
Small amounts of caffeine might make your blood pressure go up, increase your heart rate, and make you pee more. If you have caffeine close to bedtime, you may have trouble falling asleep, sleep for a shorter time, or not sleep as deeply.
Larger amounts of caffeine (600 mg or more) can:
People with anxiety disorders or heart problems shouldn't use large amounts of caffeine because it can make their condition worse.
It's rare for adults to die from having very large amounts of caffeine (overdose). People born with heart problems have died from drinking large amounts of energy drinks that contain caffeine and herbal stimulants.
Most healthy adults that use low to moderate amounts of caffeine (up to 3 cups of coffee) every day don't seem to have any long-term effects.
Regular use of more than 600 mg of caffeine a day might cause long-term effects such as sleep problems, thinning of bones and fractures, more anxiety, and stomach acidity. It can also increase blood pressure, and if you already have high blood pressure, it can get worse.
More than 300 mg of caffeine (about 2 to 3 cups of coffee) in a day may be linked to miscarriages and low-birth weight in babies.
Caffeine is passed through breastmilk, which might make your baby irritable or have trouble sleeping.
If you're pregnant or breastfeeding you may want to limit or not have any caffeine.
Caffeine doesn't help you sober up if you drink too much alcohol.
Mixing caffeine and alcohol puts you at higher risk of drinking and driving or getting into a vehicle with someone who has been drinking. You might not realize the person has had too much alcohol, and the caffeine or energy drink might mask the drowsiness from alcohol.
You might also drink more than normal if you combine alcohol and caffeine (such as mixing alcohol with an energy drink). The more alcohol you drink, the higher the risk that you may pass out or have an alcohol-related injury.
Some products with caffeine, such as some energy drinks, have higher than the recommended doses of caffeine for children and teens. Because children and teens weigh less than adults, even a low amount of caffeine may harm them.
Children who drink pop or energy drinks with caffeine may feel restless, have behaviour problems, be irritable, have trouble sleeping, or wet the bed. Children can get very sick from even small amounts of caffeine.
Some teens who use a lot of caffeine may have health problems such as an increased or abnormal heart rate and chest pain. If this happens, they may have to go to the hospital or need an ambulance.
College and university students might use lots of caffeinated products (such as coffee, energy drinks, caffeine pills) to stay awake and study longer.
Lack of sleep and stress from school might make the effects of caffeine worse. It's important to find healthy ways to manage stress and get enough sleep.
As your body gets used to caffeine, you need more and more of it to get the same effect (tolerance). As the amount of caffeine you have goes up so does the risk of side effects.
If you suddenly stop drinking caffeine, you might have withdrawal symptoms such as:
Withdrawal symptoms begin 12 to 24 hours after you stop caffeine. Most symptoms go away within a few days.
If you're concerned about your or someone else's caffeine use, or you want to learn more about substance use, call the Addiction and Mental Health Helpline, any time of the day or night, at 1-866-332-2322 (Alberta only).
Current as of: June 1, 2023
Author: Poison & Drug Information Service, Alberta Health Services
This material is not a substitute for the advice of a qualified health professional. This material is intended for general information only and is provided on an "as is", "where is" basis. Although reasonable efforts were made to confirm the accuracy of the information, Alberta Health Services does not make any representation or warranty, express, implied or statutory, as to the accuracy, reliability, completeness, applicability or fitness for a particular purpose of such information. Alberta Health Services expressly disclaims all liability for the use of these materials, and for any claims, actions, demands or suits arising from such use.