Other Drugs


What is caffeine?

Caffeine is a central nervous system stimulant. It's one of the most popular drugs in the world, consumed by up to 90% of people in the world in one form or another, but mostly in beverages. It is a naturally occurring substance found in plants like cocoa beans, tea leaves, and kola nuts.

What are the effects of caffeine?

Caffeine's strongest effects are felt for about an hour after taking it, but some effects last 4 to 6 hours. Caffeine causes increased neuron firing in the brain which the pituitary gland perceives as an emergency and therefore causes the adrenal glands to release adrenaline. Caffeine also increases dopamine levels -- the neurotransmitter that is affected by drugs like amphetamines and heroin. Obviously, it does this on a much reduced level from those drugs, but this may be the source of caffeine's addictive quality.

While caffeine is mildly addictive, it has not been shown to have a direct link with any serious health risks. Still, anyone who's been up all night after drinking too much coffee can tell you that caffeine can affect a person's mood and sleep pattern. Here are some of the frequent effects of caffeine:

  • Caffeine is a diuretic. Caffeine prompts the body to lose water through urination. This can lead to dehydration and is the reason that caffeinated drinks are not a good idea when working out or doing other activities that require fluids. In fact, it is suggested that you add 8 ounces of water for every cup of coffee you drink.

  • Caffeine can cause you to feel jittery, skittish, restless, excitable or anxious. It can temporarily speed the heart rate. If you're feeling stressed out, then a cup of coffee can exacerbate, rather than help, this feeling. Too much caffeine can hurt a person's ability to concentrate, making it difficult to study.

  • Caffeine can cause insomnia. It can be very hard to fall asleep when you take a lot of caffeine. This is especially true if you take it at night, but is also true of higher doses earlier in the day.

  • Caffeine at high doses can cause headaches.

  • Some caffeinated beverages can have other health effects. For instance, the acid in coffee can upset the stomach, and coffee (though not the caffeine in it) can worsen ulcers, raise blood pressure and blood cholesterol, and speed up the heart rate, increasing the risk of heart disease.

  • Caffeine can have negative effects on pregnant women or on women who would like to become pregnant including an increased risk for difficult conception and miscarriage. Caffeine is transmitted through the placenta and through breast milk to the baby. Therefore, if you're pregnant or thinking about becoming pregnant, the FDA recommends that you stop taking caffeine or cut back to 1 cup per day.

How much caffeine am I having?

In the U.S., the average person drinks 200 milligrams a day (about two 8 ounce cups of coffee). Check out the list below to see how much you're having.


Serving Size

Average Amt. (mg)

Range (mg)

Brewed Coffee

8 ounce



Instant Coffee

8 ounce



Decaf, Brewed

8 ounce



Decaf, Instant

8 ounce




Single 2 ounce




2 ounce




2 ounce



Black Tea

8 ounce



Decaf Black Tea

8 ounce



Green Tea

8 ounce



Iced tea mix, unsweetened

8 ounce



Iced tea, ready to drink

8 ounce



Cocoa beverage

5 ounce



Chocolate Milk

8 ounce



Dark chocolate, semi-sweet

1 oucne



How do I cut back on caffeine?

Remember that caffeine is addictive. If you feel like you can't get going in the morning, feel overtired during the day from not having caffeine, or get headaches when you try to stop taking caffeine regularly, these are signs of dependence.

If you're having trouble sleeping, feel like you are consuming too much caffeine or you don't like the effects of caffeine on your body, here are some suggestions for quitting or cutting back:

  • Switch to decaffeinated beverages, or to a mixture of decaffeinated and regular coffee.

  • Reduce the number of caffeinated drinks you have every day. If you have coffee in the morning and a Coke in the afternoon, try skipping the Coke and replace it with water or juice.

  • Brew tea for a shorter time. The less time you brew it, the less caffeine it will contain. Try herbal teas which usually don't contain caffeine.

  • Watch out for soft drinks and energy drinks like Red Bull which can contain added caffeine. This will be listed on the label.

  • If you are trying to quit and feel yourself getting a headache, you can try having a small amount of caffeine to alleviate the headache. For some people, this helps keep up the momentum to quit.

  • Know what's in over-the-counter medications. These can contain large doses of caffeine, too.

  • Drink water or non-caffeinated drinks when you're thirsty. Remember, caffeinated beverages will only add to your body's dehydration. 

What other stimulants contain caffeine?

Some herbal stimulants can contain naturally occurring caffeine, especially guarana and mate. This caffeine can have the same effects as coffee or tea. Be careful of energy drinks, which can contain up to 80 mg of caffeine and other stimulant ingredients. See our web page on energy drinks for more information.  

What about caffeine powder?

Powdered, pure caffeine is being sold in stores and on the internet.  It is very dangerous, because one teaspoon of the powder is approximately the equivalent of 25 cups of coffee.  The FDA issued a warning in 2014, urging people to avoid caffeine powder and indicating that at least two young men died after taking the powder.

Symptoms of caffeine overdose can include rapid or dangerously erratic heartbeat, seizures and death. Vomiting, diarrhea, stupor and disorientation are also symptoms of caffeine toxicity. These symptoms are likely to be much more severe than those resulting from drinking too much coffee, tea or other caffeinated beverages. Read more here.

Related Links

How Stuff Works
This link has medical and chemical information on caffeine as well as the breakdown of how much caffeine is in medications like Anacin, Vivarin and Dexatrim.

The American Dietetic Association 
This link has several brief articles on caffeine, including Cutting Down on Caffeine, Chocolate: Facts and Fiction and Straight Facts About Beverage Choices.

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