How long does the caffeine effect last?

Caffeine is a great source of that much-needed kick every time we need to extend our waking hours. It serves as our energy booster to make it through an entire day.

When the first sip of caffeine hits, you surely feel transformed in so many ways. Your overall mood changes positively, your body feels it can do more physical activities and your concentration becomes aligned and clearer – in short, you feel invigorated at all levels. 

However, as much as you want to stay alert and energised, using caffeine has its limits. Caffeine effects do not stay long in your system and will eventually die down. This is actually the reason why many people become dependent on caffeine. With it being a fast-acting stimulant on your central nervous system, some people find the effects of caffeine really helpful to function accordingly in their everyday lives. 

How long does caffeine stay in your system?

As mentioned above, caffeine can only give you its amazing effects for a limited time of about four to six hours. 

To further explain this, scientists who studied how long caffeine effects last derived the term “half-life.” This refers to the time when the starting amount of the caffeine substance is reduced by half. Meaning half of the caffeine you consume is still in your body after drinking a caffeinated beverage for six hours [1]. Thus, if you plan to consume at least 200 milligrams of caffeine, you would still have 100 milligrams of it present in your body after five to six hours. 

Your body usually needs about 45 minutes to absorb caffeine fully in your bloodstream [2]. However, it only takes 15 minutes after that first sip of caffeine beverage for you to feel its effects. It peaks for a minimum of one hour to several hours, depending on your tolerance. Additionally, you should wait until 10 hours to be completely free from caffeine. 

Common effects of caffeine when consumed 

Caffeine, which is common in coffee, soda and tea, can be consumed wherever you prefer. It is a harmless substance that comes from the leaves and seeds of many plants. Many people indulge in caffeinated drinks for a very particular reason – we use caffeine to stay away, exploiting its ability to block the sleeping-promoting chemicals that try to get us to do the opposite. [3].

With the blocking process taking place in our central nervous system, caffeine has many effects on the person who consumes it. We can categorise these through short-term and long-term effects. 

Short-term effects 

The majority of caffeine drinkers have experienced its harmless short-term effects. Among these are higher blood pressure, increased heart rate, and higher frequency of urination at the time. Caffeine’s classic effects are well known – it helps you to stay awake, stay alert and remain vigilant.

Those who consume caffeine a few hours before sleeping will experience difficulty in falling asleep, as well frequent awakenings during sleep and shorter sleep times. There are also possibilities of feeling tired the next day and having very low energy because of disrupted circadian rhythms. 

Consuming large amounts of caffeine, typically around 600 mg above, can cause shaking, trouble sleeping at any time, feeling agitated, fast or irregular heartbeat (or palpitations), restlessness, fidgeting and anxiety. 

Long-term effects 

As caffeine is considered to be one of the most consumed natural-made drugs, many people who frequently drink this may develop long-term effects. An average number of caffeine intake every day may not cause any harm to you. This is typically around three cups of coffee on a daily basis. 

However, women who love to drink coffee more than three cups a day can be prone to having bone fractures, especially with their hips as they age. There are also apparent studies that taking more than 300 mg of caffeine can actually be linked to miscarriages and low-birth-weight babies. 

With a regular intake of more than 600 mg of caffeine, you may develop chronic insomnia, constant anxiety, depression and stomach problems. Moreover, the regular high blood pressure you have may also worsen. 

Caffeine overdose can rarely cause death in adults. In order for this to happen, you would need to inject around 3.9 grams of caffeine or swallow about 10 grams. 

Surprisingly, a larger study was made about the benefits of caffeine intake and the results give a new perspective to view caffeine. It shows that people who usually drink up to eight cups of coffee per day may slightly lower their risk of early death, in comparison to those non-drinkers [4]. This study, which was conducted for 10 years, involved about half a million Britons and concluded that more intake of coffee could lower the risk of dying. 

Factors that contribute to how caffeine effects last

To fully understand how caffeine effects last in your body system, you can look at these several factors contributing to its effects period. 

  • Caffeine intake amount: basically, the effects of caffeine last depending on the amount you consume. The recommended dose of caffeine is around 200 to 300 milligrams; hence, if you consume more than that, its effects can last more than the regular time of four to six hours. Drinking different types of coffee, such as espresso, brewed or instant, can also give you different periods of caffeine effects. You must also consider your age, weight and sex. 
  • High tolerance, low tolerance or caffeine dependence: you also have to consider whether you drink caffeine beverages regularly or not as it affects the time of its effects on you. As you frequently consume caffeine, you will most likely develop low intolerance, meaning fewer side effects and shorter time of caffeine effects. Caffeine dependents, those who can’t function without caffeine, will somewhat get used to the effects and consider them as their normal state. 
  • Water intake: drinking water is the basic way to stay healthy. Being hydrated before consuming caffeine can improve its effects on you and its time on your system. You can also reduce caffeine’s negative effects with water, like anxiety, palpitations and headaches, because it can flush out the caffeine in your body. 
  • Caffeine and yourself: generally, are you sensitive to caffeine? Caffeine itself is considered to be a psychoactive drug; hence, your experience in drinking caffeine can greatly depend on you and your regular habits

Myths about caffeine effects

Over time, as we incorporate caffeine into our lives, we create different myths about drinking caffeinated beverages. Number one on this list is the idea that caffeine can only be found in drinks, especially in coffee. However, caffeine can also be used for certain medications. Caffeine can be deployed to treat headaches and migraines and is used as a vital ingredient for pain relievers. 

Next, caffeine decreases your appetite – it does not. There is no scientific evidence that can link it as a part of your diet or decrease the need to eat. Caffeine also does not help you sober up when you are drunk. Plus, combining alcohol and caffeine, especially in energy drinks, can have tremendous negative effects on you.

People who should avoid caffeine 

Although there are many good benefits and side effects of caffeine to us, it is not really for all people. There are certain individuals who should avoid caffeine as much as possible. If you are struggling with constant panic attacks, drinking caffeinated beverages in large amounts can worsen these and trigger anxiety and nervousness. 

Furthermore, children can actually die from too much caffeine for only 1 gram of it. A higher intake of caffeine than the suggested doses in some products for kids and teens can cause health and behaviour problems [5]. 

Drinking too much soda or energy drinks for children can cause anxiety, irritability, trouble sleeping and wetting in bed. The negative effects of caffeine on teenagers can be abnormal heart rate or chest pain. 

If you are a postpartum mom and breastfeeding, it is better to avoid consuming caffeine because this can be passed to your baby through breast milk. Then, your baby will have trouble sleeping and some digestive problems. 

Overall, the effects of caffeine and how long it lasts vary from one person to another. You should consider different factors to ultimately determine how long caffeine effects last on you. Caffeine can have positive and negative effects based on your consumption; hence, we really recommend to always stay balanced. 


Photograph: Billion Photos/ShutterStock
The information included in this article is for informational purposes only. The purpose of this webpage is to promote broad consumer understanding and knowledge of various health topics. It is not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of your physician or other qualified health care provider with any questions you may have regarding a medical condition or treatment and before undertaking a new health care regimen, and never disregard professional medical advice or delay in seeking it because of something you have read on this website.