Effects on caffeine

The Buzz About Caffeine

It’s always tempting to kick-start our day with a caffeinated boost, and it may even be a form of motivation for us to get out of bed. But do we know what caffeine really is and what it does to our bodies? Let’s explore the science behind this stimulant!
By the team at Speedoc,
March 15, 2024

In today's fast-paced world, many of us turn to caffeine to kick-start our mornings or push through a mid-afternoon slump. Whether it's in the form of coffee, tea, energy drinks, or supplements, caffeine is one of the most widely consumed psychoactive substances in the world. However, many of us do not know what caffeine exactly is, and what it does to our bodies.

What is caffeine?

Caffeine is a natural central nervous system stimulant of the methylxanthine class found in tea, coffee and cacao plants. It works by blocking the action of adenosine, a neurotransmitter responsible for promoting sleep and relaxation which leads to increased alertness and reduces the perception of fatigue, making it a popular choice for combating drowsiness.

What does caffeine do to your body?

Caffeine has several effects on the body, including:

  1. Laxative effect
  2. Dilation of airways
  3. Increased heart rate
  4. Mood enhancement
  5. Constriction of blood vessels
  6. Enhanced physical performance
  7. Central nervous system stimulation
  8. Diuresis (aka increases urine production)
Array of coffee options

Signs of caffeine toxicity

Most adults can safely consume about 400 milligrams of caffeine a day (approximately four average-sized cups of brewed coffee) but there are many factors that one should take into consideration as to how much caffeine you can tolerate.

Some of the signs and symptoms of having too much caffeine:

  • Dizziness
  • Headaches
  • Dehydration
  • Rapid heartbeat
  • Trembling hands
  • Difficulty sleeping
  • Increased urination
  • Restlessness and excitability

Alternative sources of caffeine

There are several alternatives to caffeine for those seeking a boost in energy or alertness without the side effects and health implications associated with caffeine consumption.

Vitamin B12 supplements: Chronic tiredness and fatigue may be a result of the deficiency in vitamin B12. In such instances, supplements may be a better option to nip the problem at the bud instead of chugging caffeine-laden beverages.

Chicory coffee: A caffeine-free substitute made from roasted, ground, and brewed chicory root.

Kombucha: Contains about one-third the amount of caffeine as one cup of black tea would have.

Matcha: Aside from being a powerful antioxidant and its long list of health benefits, one serving of matcha contains a lot less caffeine than a serving of coffee. 

Who should take special precaution when consuming caffeine?


Kids should limit their daily caffeine intake to 2.5mg per kilogram of body weight. Exceeding this recommended amount can potentially affect sleep and behaviour, negatively impacting their ability to thrive in school.

Pregnant women

Pregnant women are advised to limit their caffeine intake to 200mg per day or less, due to its potential effects on foetal development.

People with GERD or acid reflux

Caffeine can stimulate the production of stomach acid, which may worsen symptoms of gastroesophageal reflux disease (GERD) or acid reflux. Individuals with these conditions may experience increased heartburn or discomfort after consuming caffeine and may need to limit their intake.

Speedoc doctor consultation on safe caffeine dosage

The ubiquitous availability of caffeinated products at every turn paired with its known stimulating effects on the body and mind, it is no wonder why caffeine is pegged as the “world’s favourite drug”.

While moderate consumption can offer benefits such as increased alertness, improved cognitive function and enhanced physical performance, it is essential to be mindful of potential risks associated with excessive intake. By understanding how caffeine affects our bodies and practising moderation, we can enjoy its perks while minimising potential drawbacks.

As with any dietary component, it is always wise to consult with a healthcare professional to determine what level of caffeine consumption is safe for you.

Consult a doctor virtually at your convenience!
Download the App