Mar 10, 2022


How Much Caffeine is Too Much?

Female drinking big cup of coffee

If you are reading this, chances are you are a part of the 90% of American adults who consume caffeine every day. Whether it's to help get you out of bed or through that 3 PM Zoom meeting, caffeine is the go-to for many of us. 

But is there such a thing as too much? Before you grab your next cup of joe, let's explore what's considered a healthy and an unhealthy amount. 

What is caffeine?

Caffeine is a natural stimulant that blocks adenosine, a neurotransmitter responsible for slowing down nerve cell activity and causing sleepiness.

By stimulating the brain and central nervous system, caffeine increases energy levels, improves physical and mental performance, enhances concentration, and can help burn fat

What is caffeine found in?

Caffeine is often associated with coffee, tea, soda, and energy drinks. However, caffeine is also found in numerous foods, drinks, and even medications such as:

  • chocolate 

  • yerba mate

  • weight loss supplements

  • cough syrup 

  • some prescription drugs (i.e., Migergot, Fioricet/Codeine, Norgesic Forte)

  • some over-the-counter pain relievers (i.e., Excedrin Migraine, Goody's Headache Powder, Midol Menstrual Maximum Strength Caplets)

Adverse effects of too much caffeine

While caffeine can positively affect the body, too much of it can cause some bad reactions. If you consume caffeine in excessive amounts, you may experience:

  • increase in body temperature

  • frequent urination

  • dehydration

  • dizziness 

  • headaches

  • rapid heartbeat (palpitations)

  • anxiety

  • irritability

  • trembling hands

  • insomnia or disruptive sleep

Though not typical, it is possible to consume lethal doses of caffeine. Between 5 to 10 grams of caffeine ingested quickly is considered fatal and is often the cause of an overdose on caffeine pills

How much caffeine should you be consuming?

Experts suggest no more than 400 mg per day for the average-weight adult. That's equivalent to roughly 4 cups of coffee, 10 cans of soda, two "5-hour energy shot" drinks or 8 cups of black tea. 

However, that number isn't set in stone and can depend on factors like:

  • bodyweight

  • medications you take

  • sensitivity

  • medical conditions 

  • age


Since researchers based the daily max caffeine amount on the average human weight, the number can adjust depending on your individual weight. If you weigh more, you can safely consume more, and if you weigh less, you should have less. 

You can use a caffeine calculator or speak to your doctor about how much caffeine is safe for your current body weight. We recommend always consulting with your physician if you have other factors to consider in addition to body weight. 

Medications and supplements

According to, there are currently 56 prescription medications that are known to interact with caffeine. 

There are four that can cause severe/major interactions:

Caffeine should be avoided or limited if you are taking any of these below drugs, as well: 

This is not an inclusive list. The above medications mentioned are the brand names only, but you should also avoid caffeine for the generic versions as well. Always ask your pharmacist and doctor about possible interactions with any medicines and supplements you are currently on. 

Sensitivity or allergy to caffeine 

Believe it or not, caffeine sensitivity and caffeine allergy are two different things. 

Some people experience hypersensitivity to caffeine, meaning they can't even tolerate small amounts without experiencing adverse side effects. This sensitivity can be due to genetics or the liver's inability to metabolize fast enough. You may have a sensitivity if you experience the following side effects after just a sip or two of caffeine:

  • racing heartbeat

  • headache

  • jitters

  • anxiousness

  • restlessness

  • insomnia

A caffeine allergy occurs when your immune system thinks caffeine is a harmful invader. As a result, your body produces antibodies to fight it off. An allergic reaction to caffeine often includes:

  • itchy skin

  • hives

  • swelling of the throat or tongue

  • difficulty breathing and anaphylaxis

You should seek emergency care right away if you have an allergic reaction, as it can be life-threatening. 

Medical conditions

Caffeine should be eliminated or decreased for certain medical conditions, as it can cause symptoms to accelerate or cause more severe side effects. 

Pregnant or breastfeeding

The American Pregnancy Association and The American College of Obstetrics and Gynecologists recommend no more than 200 mg of caffeine a day during pregnancy. Because of inconclusive research, many experts say the less you consume, the better. 

Research shows that a small amount of caffeine does cross over to breast milk. However, The American Academy of Pediatrics (AAP) suggests that it's relatively safe for nursing mothers to have caffeine. You should limit how much due to the possibility of it causing sleep issues with your baby. 

Heart disease 

If you have an arrhythmia or similar heart condition, you should consult with your doctor on how much caffeine is safe to consume. Too much caffeine can cause an increase in your heart rate, causing further issues. 

High blood pressure

Often temporary, caffeine can cause a rise in blood pressure. Therefore, if you already suffer from high blood pressure, you should ask your doctor the safe amount to consume. 

Sleep disorders

Caffeine, especially in the afternoon and evening, can cause issues with your sleep quality. Experts recommend avoiding caffeine six hours before bedtime and cutting back altogether if you still suffer from poor sleep. 

Migraines/chronic headaches 

Caffeine can be used to treat headaches, as it's often found in certain over-the-counter pain and migraine medications. However, some studies have found that too much can make migraines worse.


Excessive caffeine can mimic anxiety symptoms. It can also worsen symptoms of those with anxiety. In addition, caffeine can have a negative reaction with many anti-anxiety medications. 


While caffeine doesn't cause GERD or stomach ulcers, it can aggravate symptoms causing them to become worse. Your doctor may recommend you eliminate caffeine from your diet to see if it helps alleviate symptoms. 

Crohn's Disease and Irritable Bowel Syndrome(IBS)

Coffee is acidic and can have laxative properties. Therefore, too much of it and caffeine may result in flare-ups, discomfort, and increased diarrhea in those who suffer from IBS or Crohn's Disease


The AAP recommends that children under 12 shouldn't consume any caffeine. Many experts say teens should limit their intake to less than 100 mg per day. However, there is no safe amount of caffeine for children in general. 

Caffeine has been shown to cause many medical conditions and issues in children, such as:

  • obesity

  • deficiency in essential vitamins and minerals

  • dehydration 

  • tooth decay 

  • sleep problems

  • impact on mental and physical development 

  • behavioral problems 

  • mood swings

  • increased risk of developing anxiety

Final thoughts

A natural stimulant commonly found in coffee, tea, and soda, caffeine is also found in other food, drinks, medications, and supplements. It alters brain and body function while providing positive effects like improved performance, weight loss, and increased energy and alertness. 

Caffeine should be consumed in moderation, as prolonged, excessive caffeine consumption can affect your overall health and wellbeing. 

Those who suffer from adverse side effects, like trouble sleeping, taking certain medications, or living with specific medical conditions, may want to limit or avoid caffeine altogether. 

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