How Much Caffeine Is Safe To Have Daily?

How Much Caffeine Is Safe To Have Daily?

You can't imagine starting a day without a nice cup of coffee. Sweet or unsweetened, strong or with milk, coffee proves to be versatile, and every person has their preferences. When you wake up in the morning, coffee gives the "kick" you need to get ready and function at work. Indeed, the benefits of coffee are numerous but have you ever wondered how much is too much? Thats what were going to talk about in this post – safe daily caffeine dosage. Read on to learn more.

How much caffeine is safe?

Since caffeine is a stimulant that produces alertness and increases energy levels, the general belief is that the more you drink, the more it can do for you. Indeed, the effects of caffeine are largely dose-dependent, but there are some limits you shouldn’t cross. You see, if you consume too much caffeine, you may experience some adverse reactions. We'll discuss the side effects of excessive caffeine intake below.

But how much caffeine is considered safe?

The answer is not so simple because the impact of caffeine differs from one person to another. Your age and overall health play a role here. Lets take a look at the daily amounts of caffeine considered safe for different groups of people.

Caffeine intake in healthy adults

The U.S. Food and Drug Administration (FDA), the European Food Safety Agency (EFSA), Health Canada, and the U.S. National Academies of Science (NAS) agreed that caffeine intake of up to 400mg a day is considered safe and not likely to induce side effects.

Food Standards Australia New Zealand also reported 400mg is considered safe for persons over the age of 18, emphasising a maximum of 200mg of caffeine in a single serving.

How much is 400mg caffeine? It depends on the source of caffeine. But generally speaking, 400mg a day is the amount of caffeine from four cups of brewed coffee. Its also the amount of caffeine in 10 cans of cola or two energy shot drinks. If you tend to consume other caffeine-containing products, make sure to check the labels to see the amount of caffeine they contain. That way, you will know whether you're consuming enough or going overboard.

However, EFSA indicates that 200mg of caffeine at once doesn’t cause health concerns when consumed less than two hours before intense physical exercise. They also call for caution because consuming about 100mg of caffeine close to bedtime may affect the quality of your sleep.

IMPORTANT: the half-life of caffeine is five hours, on average, meaning you probably have caffeine in your blood if you drank coffee within the last 10 hours.

Caffeine intake in pregnant and breastfeeding women

Pregnant and breastfeeding women need to practice caution with diet. Everything you consume can either benefit or harm your child. When it comes to caffeine, 200mg a day is considered safe. Some reviews have found that taking 300mg per day is also safe, but it may not be the best move since you're too close to the daily limit for healthy adults, and thereby the risk of side effects may increase.

When it comes to the consumption of caffeine among pregnant and breastfeeding women, it's important to mention randomised controlled trials in this area are scarce. For that reason, sticking to a lower dosage of caffeine a day (up to 200mg) is a reasonable thing to do. Available evidence on this subject confirms the data about caffeine intake of 300mg a day or higher are limited and conflicting, meaning it could be best to consume less than 300mg.

Sticking to a lower dosage of caffeine per day is particularly important if we bear in mind that the half-life of caffeine increases from an average of three to five hours in a non-pregnant person to 10.5 hours during the last four weeks of pregnancy. Basically, the pregnant body takes a lot longer to eliminate the caffeine you consume. In other words, the body holds on to caffeine you ingest in the morning a lot longer and adds it to the caffeine you consume in the afternoon. This may result in higher doses of caffeine than its considered safe.

Caffeine intake in adults with cardiovascular problems

Millions of people have cardiovascular problems and need to be careful with the foods they eat or beverages they drink. Caffeine ingestion can elevate blood pressure for three to four hours, studies show. That being said, caffeine tolerance appears to diminish the acute effect of caffeine on blood pressure. Those with hypertension (high blood pressure) are more susceptible to blood pressure changes. In other words, the effect of caffeine on blood pressure may decrease with regular intake.

In healthy men and women, caffeine intake of up to 400mg per day isn’t associated with an increased risk of cardiovascular problems. That being said, the long-term effects of caffeine are less certain in persons with hypertension or pre-existing cardiovascular problem. For that reason, it may be wiser to stick to a lower intake of coffee and caffeinated beverages. If you have some cardiovascular problem, you may want to consult a doctor regarding the safest dose of caffeine for your specific condition and health status.

Caffeine intake in children and adolescents

Information to determine safe caffeine intake for children and adolescents is insufficient. Many health organisations recommend parents avoid giving their children caffeinated products. Caution is necessary when it comes to energy drinks as well, which are popular among adolescents but are laden with caffeine.

As Food Standards Australia New Zealand reports, children and adolescents under the age of 18 shouldn’t consume more than 3mg per kg of body weight. Of course, the best thing to do is to ensure your child is not exposed to caffeinated products.

What happens when you consume too much caffeine?

As seen above, consuming more than 400mg of caffeine a day increases the risk of adverse reactions. You may be particularly prone to side effects if youre not a regular coffee drinker. The symptoms that occur with excessive consumption of caffeine include:

  • Anxiety – caffeine is well-known for its potential to increase alertness by blocking the effects of adenosine (a brain chemical that produces tiredness). Simultaneously with blocking adenosine, caffeine stimulates the secretion of adrenaline which gives you energy. That said, higher doses of caffeine pronounce these effects and induce anxiety and nervousness.
  • Insomnia – caffeine is a stimulant that, at higher doses, may increase the amount of time it takes you to fall asleep. Moreover, caffeine may reduce total sleeping time, particularly in older adults. It’s useful to know low or moderate caffeine intake may not affect the quality of sleep.
  • Digestive problems – coffee has laxative effects due to the release of gastrin, a hormone produced in the stomach to accelerate the activity of the colon. Additionally, caffeine may stimulate bowel movements through the increase of peristalsis, the contractions that move food through a person’s digestive system. At large doses, caffeine loosens stools and may cause diarrhoea. Excessive caffeine intake may worsen gastro-oesophageal reflux disease in some persons.
  • Muscle breakdown – although rare, excessive consumption of caffeine may be associated with rhabdomyolysis, a serious condition wherein damaged muscle fibres enter the bloodstream and cause problems such as kidney failure.
  • Dependence – although most people don’t think about it this way, caffeine is habit-forming and may stimulate some brain chemicals similar to the manner in which amphetamines and cocaine do. Although caffeine doesn't induce the same form of addiction as illicit drugs, it may lead to forming physical or psychological dependence, particularly in higher doses.
  • High blood pressure – due to the stimulant properties, caffeine may raise blood pressure. For regular coffee drinkers, this impact isn’t that serious, especially when normal doses are involved. However, consuming excessive doses of caffeine can be harmful to your blood pressure.
  • Rapid heart rate – high doses of caffeine may accelerate heart rate in some persons. These effects may vary from one individual to another. You may want to be cautious if you're at a higher risk of developing cardiovascular problems.
  • Fatigue – although caffeinated products are known for their energy-boosting effects, they may induce the opposite when large doses are consumed. As the effects wear off, you are left feeling more tired than before
  • The urgency to urinate/frequent urination – caffeine is a stimulant, but it doesn't act on the brain only; it can also stimulate your bladder. For that reason, consuming higher doses of coffee may lead to the urgency to urinate or frequent urination.

Can you overdose on caffeine?

People can overdose on a lot of things ranging from medications to illicit substances. But you have probably never thought you could overdose on caffeine. Caffeine overdose is rare but a possible event that occurs with excessive consumption. In the most severe cases, caffeine overdose can be life-threatening. However, in most cases, the affected person experiences unpleasant symptoms that go away once the caffeine is excreted from their body.

While some people consume a lot more than recommended during the day and do not experience an overdose, its important to stick to the recommended values to avoid risking complications. Those who rarely consume caffeine are more likely to overdose. That being said, even if you're a regular consumer of caffeine, you should stop if you experience uncomfortable symptoms.

The most common symptoms of caffeine overdose include:

  • Irritability
  • Dizziness
  • Fever
  • Diarrhoea
  • Headache
  • Insomnia
  • Increased thirst

These symptoms may not seem serious at first, which is why a person may not assume caffeine overdose is the culprit. More serious symptoms may also occur, including:

  • Hallucinations
  • Difficulty breathing
  • Convulsions
  • Uncontrollable muscle movements
  • Vomiting
  • Chest pain
  • Confusion
  • Fast or irregular heartbeat

These symptoms require immediate medical assistance, so you shouldn't ignore them.

If you suspect you have caffeine overdose (or someone else), make sure to inform the doctor about caffeinated items you had consumed before symptoms occur. You should also inform them about the quantity you ingested. The doctor will carry out necessary tests, maybe even a drug test, in order to diagnose the issue.

Upon diagnosis of caffeine overdose, the doctor will recommend a treatment option. The main objective of the treatment is to get the caffeine out of the body while taking care of the symptoms you experience. For example, you may receive activated charcoal to prevent caffeine from getting into the gastrointestinal (G.I.) tract.

In cases when caffeine enters a patient's G.I. tract, the healthcare provider may recommend a laxative or gastric lavage, the use of a special tube to wash out the contents from the stomach. The doctor determines the right approach based on the severity of your symptoms; the goal is to get the caffeine out of the G.I. tract as quickly as possible.

If coffee is decaffeinated”, does it mean it has no caffeine at all?

This is a common misconception – people often believe decaffeinated products have zero caffeine. The reality is that these products only contain lower amounts of caffeine than their counterparts. For instance, an 8oz cup of decaffeinated coffee may still contain about 2mg to 15mg of caffeine. Therefore, if you dont react well to caffeine or want to avoid potential risks, you may want to avoid consuming decaffeinated products too.

How to reduce caffeine intake without side effects?

If youre used to drinking a lot of coffee or other caffeinated beverages and decide to cut back, youre probably worried about potential adverse reactions. The best way to significantly reduce caffeine intake is to do it gradually. You dont want to stop abruptly because it may cause withdrawal symptoms. Instead, lower the intake of caffeine regularly until you stop consuming coffee entirely or at least reach the dosage that works for you.


Most people love coffee, but we often fail to acknowledge it's possible to have too much. Healthy adults shouldn't consume more than 400mg a day. Avoid consuming too much caffeine to so you’re not facing adverse reactions associated with it. Moderate consumption is the solution for those who want to experience the benefits of coffee without risking unpleasant effects.


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