What is caffeine?

Caffeine is the stimulant in your coffee, tea, chocolate and soda that reduces tiredness, increases alertness and gives you a boost of energy. It can also cause insomnia, headaches, dehydration and high blood pressure, if you’re not careful. For many, caffeine is a tool to help them wake up, perk up and concentrate. Hack its benefits, and it can help you get through the day.

Caffeine is a white, bitter substance that’s found naturally in over 60 plants, including coffee beans, tea leaves and cacao pods that are used to make chocolate. The U.S. Food and Drug Administration (FDA) considers caffeine to be both a food additive and a drug.

The amount of caffeine in your food and drink varies. For coffee and tea, the amount of caffeine per cup depends on the brand, the type of beans or leaves used, how it is prepared and how long it steeps. Coffee can have as little as two milligrams of caffeine (decaf coffee) per cup, and as much as 200 milligrams per cup. Your typical tea has about 40 milligrams of caffeine, but it can range from nine to 110 milligrams. Twelve ounces of soda pop/soft drink usually has 30 to 60 milligrams of caffeine. Eight ounces of an energy drink has between 50 and 160.

What effect does caffeine have on the body?

Caffeine passes into your bloodstream from your stomach and small intestine. Once in your bloodstream, caffeine stimulates your central nervous system – your nerves, brain and spinal cord – to make you feel more awake and alert. Caffeine reduces fatigue and improves focus and concentration. It also causes the release of acid in the stomach, and you might have heartburn or indigestion after consuming caffeine.

When you drink or eat caffeine, the dopamine signaling in your brain is enhanced. Dopamine is a chemical that helps with controlling motivation, emotions and movement. You feel more alert and awake when the signaling increases.

How much caffeine is too much?

The average American adult consumes 200 mg of caffeine a day. This is the equivalent of two five ounce cups of coffee or four 12 ounce colas. Consuming up to 400 mg or four cups of coffee does not cause problems for most people. But, caffeine affects people differently, depending on their size, gender and sensitivity to it. If you’re sensitive to caffeine, even moderate amounts can cause insomnia (trouble sleeping), rapid heart rate, anxiety and feelings of restlessness. Health and nutrition experts agree that consuming more than 600 mg of caffeine a day (equivalent of four to seven cups of coffee) is too much.

What are the symptoms of having too much caffeine?

Symptoms of having too much caffeine may include:

  • Headache, nervousness, dizziness.
  • Having “the jitters” or feeling shaky.
  • Insomnia or sleep that is “on and off” throughout the night.
  • Racing heart or abnormal heartbeat.
  • Increase in blood pressure.
  • Dehydration.

Who should avoid caffeine?

It’s not safe for everyone to have caffeine in their diet. Ask your healthcare provider how much is ok for your unique body. You may want to avoid caffeine if you:

  • Have any sleep disorder, like insomnia.
  • Have ulcers or GERD.
  • Are pregnant.
  • Are breastfeeding.
  • Have migraines or chronic headaches.
  • Have high blood pressure.
  • Take certain stimulants, antibiotics, asthma medicines and heart medicines. These medications can have interactions with caffeine.
  • Are a child or teenager.
  • Have anxiety.
  • Have a fast or irregular heartbeat.

Is caffeine addictive?

Many people develop a tolerance for caffeine. This means that your body adjusts and gets used to having caffeine every day. Over time, you might find that you must keep increasing your caffeine intake to achieve the desired effects of alertness and ability to concentrate.

Your body can have a dependence on caffeine, but it’s not technically an addiction. It raises dopamine, but the level is small. Illegal stimulants like methamphetamine (“meth”) and MDMA (“ecstasy” or “molly”) cause a huge surge that messes with the reward circuits in your brain. You get “addicted” to ecstasy, and “dependent” on caffeine.

How long does caffeine last in the human body?

The effects of caffeine can be felt as soon as 15 minutes after it is consumed. The level of caffeine in your blood peaks about one hour later and stays at this level for several hours for most people. Six hours after caffeine is consumed, half of it is still in your body. It can take up to 10 hours to completely clear caffeine from your bloodstream.

How is caffeine used in medications?

Caffeine is a common ingredient in many prescription and over-the-counter headache remedies, pain relievers and cold medicines. Through caffeine’s effects on your central nervous system, it helps these drugs act more effectively. It helps your body absorb headache medicines quicker.

If you are concerned about your caffeine intake, read the product label on over-the-counter medications or the information sheet that comes with your prescriptions to determine whether a medication contains caffeine. The FDA requires that the medication labels list the amount of caffeine they contain.

Caffeine is also found in some herbal products that people take as supplements, including guarana, yerba mate, kola nut and green tea extract. These products are not required by law to show their caffeine content on the label, and there is no set standard for caffeine content.

What are some tips for quitting caffeine?

Cut down slowly on the amount of caffeine in your diet. Don’t make the mistake of stopping totally. You’ll likely experience withdrawal symptoms and go back to drinking coffee or soda or taking a headache medication with caffeine in it to make the symptoms disappear. This starts the dependency cycle all over again. Avoiding the withdrawal symptoms is one of the most common reasons why people continue their caffeine habit.

To successfully reduce your caffeine intake, gradually reduce the amount of coffee, tea, soda and energy drinks you have each day. Begin to substitute cold caffeinated beverages with water. Water is a healthy choice and satisfies the need for drinking a liquid. Water also naturally flushes caffeine from your body and keeps you hydrated.

If you are a coffee drinker, gradually switch from regular coffee to decaf. First alternate between decaf and regular, then slowly change to more decaf and taper off regular coffee. Gradually reducing your caffeine consumption over a period of two to three weeks will help you successfully change your habit without causing withdrawal symptoms.

What are the symptoms of caffeine withdrawal?

If you have developed a dependence on caffeine, an abrupt cutback can cause withdrawal symptoms that may include:

  • Headaches.
  • Tiredness.
  • Difficulty concentrating.
  • Nausea.
  • Muscle pain.
  • Irritability.

In general, the more caffeine you are used to consuming, the more severe the withdrawal symptoms are likely to be. Symptoms of withdrawal begin 12 to 24 hours after the last caffeine intake and can last two to nine days.

Caffeine can be a useful tool for an adult who needs help waking up and concentrating. But, it can also cause problems if you’re not careful with it. Don’t use caffeine too much or you could become dependent or have insomnia or headaches. Otherwise, enjoy that coffee or chocolate!

Last reviewed by a Cleveland Clinic medical professional on 12/23/2020.

References

  • Medline Plus. Caffeine. Accessed 12/20/2020.
  • Medline Plus. Medicines in My Home: Caffeine and Your Body. Accessed 12/20/2020.
  • Smith BD, Gupta U, Gupta BS, eds. Caffeinism: History, clinical features, diagnosis and treatment. CRC Press; 2008. Accessed 12/20/2020.
  • International Food Information Council Foundation. Caffeine & Health: Clarifying the Controversies. IFIC Foundation. 2008. Accessed 12/20/2020.
  • NIH: National Institute on Drug Abuse. Is caffeine really addictive? Accessed 12/20/2020.

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Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy