We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What are the Symptoms of Caffeine Intoxication?

By D. Benjamin
Updated Mar 03, 2024
Our promise to you
The Health Board is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At The Health Board, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject-matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

The symptoms of caffeine intoxication can be easily confused with symptoms of mental disorders, such as anxiety. There generally are 12 symptoms of the condition, including restlessness, nervousness, excitement, insomnia, confusion and excessive energy. The symptoms also include a flushed face, excessive urination, upset stomach, muscle twitching, irregular heartbeat and fidgeting. Suffering from five or more of these symptoms after consuming caffeine usually is a sign of caffeine overdose.

Caffeine is a central nervous system stimulant used to increase energy or alertness. Coffee is the most abundant source of caffeine, but it is also found in tea, chocolate, cola and some pain-relief medications. Many popular energy drinks combine large amounts of caffeine with sugar and herbal additives. Consuming too many of these products can lead to caffeine intoxication.

It usually requires at least 250 milligrams of caffeine — equivalent to what is found in two-and-a-half cups of coffee — to cause intoxication from caffeine. Overdose most commonly occurs when caffeine amounts greater than 500 milligrams are consumed. Caffeine naturally has a strong, bitter taste, but some people have become immune to its taste. These people cannot taste it, so they can unknowingly consume too much caffeine.

If this condition does occur, the inability to sleep is one of the most common symptoms. Although this might be temporary, it can develop into a long-term sleep disorder. Restlessness or fidgeting may become so severe that it interrupts daily activities. The condition can also cause a person to experience periods of inexhaustibility. When this happens, it is easy for the person to become dangerously overworked.

Caffeine has a diuretic effect, so excessive urination frequently happens with caffeine intoxication. If left untreated, this can cause dehydration and other dangerous conditions. Gastrointestinal problems such as nausea, vomiting or diarrhea are also common.

Excessive caffeine can make it difficult for one to think clearly. This condition is known as having an overstimulated mind. A person suffering from caffeine overdose might ramble in his or her thoughts or speech. Drinking coffee or other caffeinated drinks to promote alertness might have the opposite effect if too much is consumed.

In addition to the 12 symptoms listed above, some people experience a ringing in their ears after consuming excessive amounts of caffeine. Others have reported seeing flashes of light. Profuse sweating might also accompany intoxication with caffeine. If very high doses — more than 10 grams — of caffeine are taken, a person might experience seizures, respiratory failure and ultimately, death.

Milder forms of caffeine overdose normally will subside within four to six hours. There usually are no lasting effects of typical caffeine intoxication, but repeated caffeine overdose can cause long-term effects. It is linked to infertility, miscarriage and osteoporosis in women. Studies also have linked excessive caffeine consumption to cardiovascular diseases.

The Health Board is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Discussion Comments
By donasmrs — On Dec 10, 2013

I experienced caffeine intoxication once because of energy drinks and it was very scary. I had almost all of the symptoms -- shakes, rapid heart rate, blurry vision, anxiety and de-personalization.

I had drank several energy drinks back to back so that I could study all night for an exam. I couldn't take the exam though because I was in the hospital.

By bear78 — On Dec 10, 2013
@ZipLine-- I'm not a doctor, so this is just my opinion. You clearly had more coffee than what you are used to but I don't think you are poisoned. If you develop more symptoms though or feel ill, you should see a doctor.

I think caffeine poisoning or intoxication usually occurs with caffeine supplements or energy drinks. Most of us don't drink enough coffee for poisoning to occur. If you drink more than what you are used to, you will experience side effects. That doesn't necessarily mean that you are poisoned.

Caffeine pills or powders and energy drinks have extremely high doses of caffeine unlike natural drinks. So it's very easy to overdose with those and you will have many serious symptoms like mood changes, heart issues, hyperactivity, anxiety and dehydration.

By ZipLine — On Dec 09, 2013

Is it possible to have caffeine poisoning from three cups of coffee?

I usually only have one cup of coffee daily but today, I had three. Right now, I have the jitters and some heart palpitations. I've never experienced these issues before so I'm worried.

The Health Board, in your inbox

Our latest articles, guides, and more, delivered daily.

The Health Board, in your inbox

Our latest articles, guides, and more, delivered daily.