General Health

Effects of Caffeine That Nobody Talks About

January 24, 2022

Medically reviewed by

David Culpepper, MD

It’s no secret that the United States – nay, the world – runs on caffeine.

According to one survey, more than 85 percent of Americans consume at least one caffeinated beverage every day. Another study found that 154 million American adults (a little over half of us) drink coffee every day.

Caffeine is a powerful stimulant that has a host of physiological effects on your body beyond what everyone knows — it can boost alertness, reduce feelings of fatigue, improve your memory, and even give guys stronger erections.

It’s easy to see why so many people drink caffeine with side effects like that, but not all of caffeine's effects are positive. Hold that second pot of coffee for a second.

Where Does Caffeine Come From?

You can find caffeine in coffee, soft drinks, tea, and energy drinks. Caffeine is even found in candies like dark chocolate, gum, jelly beans, syrup, and marshmallows. Some of these foods naturally contain caffeine, but many have caffeine added during production.

Caffeine is a stimulating chemical compound, scientifically called 1,3,7-trimethylxanthine and found in more than 60 plant species around the planet. Coffee beans, tea leaves, cacao beans, kola nuts, and guarana berries are a few of the more common sources of caffeine.

These plants use caffeine as a natural pesticide. When insects try to feed on them, caffeine can paralyze and even kill them. Obviously, the effect that caffeine has on humans isn’t quite the same, but too much caffeine may have you thinking you need to go to the emergency room.

Interestingly, some prescription and non-prescriptipn medications contain caffeine. Some versions of Excedrin® (acetaminophen) contain caffeine to help fight the effects of migraine and tension headache pain, for example.

How Long Does Caffeine Stay in Your System?

You should start feeling the effects of caffeine within 15 minutes of consuming it. Peak levels of caffeine usually occur after an hour, and most people usually feel the effects for three to five hours.

The exact time that your body takes to eliminate caffeine from your blood will vary based on a few factors. For most people, it takes 10 to 12 hours before it’s removed from your system. Although the effects won’t be as strong as that first energy spike, caffeine can continue to affect your body as long as it stays in your blood.

What Are Some of the Positive Effects Of Caffeine?

Caffeine consumption stimulates the central nervous system and has a significant effect on your heart, muscles, blood pressure, and brain. When consumed in the right amount, caffeine can have several positive side effects.

Increases Alertness

The stimulating properties of caffeine can boost your brain’s production of dopamine. This neurochemical helps maintain concentration, improve focus, and boost your working memory — not to mention it’s your brain’s “reward” chemical, which is part of the reason just smelling coffee can make you warm and giddy.

For some people, caffeine may improve alertness, though not necessarily improve mental function.

Enhances Endurance

The boost of energy provided by caffeine generally helps to improve endurance. Specifically, it helps to disguise how much effort you're actually putting into physical exercise. As a result, you may be able to push yourself harder without feeling like you’re trying harder than usual.

Oddly, in some individuals caffeine has been found to have a negative effect on endurance depending when consumed.

Gets Rid of Headaches

Caffeine is commonly added to aspirin, ibuprofen, and acetaminophen in order to help these medications treat migraines more effectively. By adding caffeine, the effects of these medicines can be increased by as much as 40 percent.

Kick-starts Weight Loss

Caffeine can suppress your appetite hormones and can also stimulate thermogenesis so your body burns more fat when it’s digesting food. A combination of these factors is why studies have concluded that caffeine can be effective for reducing weight, BMI, and body fat.

Leads to Stronger Erections

Caffeine helps to relax your muscles and increase blood pressure. Both of these factors are crucial for achieving and maintaining an erection. Not only can caffeine help give you a stronger erection, it can also help to lower the odds of developing erectile dysfunction, too.

Protects Against Cognitive Decline

Caffeine can boost working memory in the short term and may be able to elevate it in the long term as well. One study showed that middle-aged coffee drinkers had a 65 percent reduced risk of developing cognitive decline, dementia, and Alzheimer’s disease.

Helps Your Colon

Caffeine has been shown to make your colon 60 percent more active than it is with water alone. Having a more active colon can benefit digestion and help your body eliminate waste faster and more efficiently — yes, we're basically validating the fact that you “go” every morning after your first few sips of coffee, and yes, it’s mostly a good thing that you do.

Are There Any Negative Side Effects of Caffeine?

The World Health Organization recognizes caffeine as an addictive substance. That's your first word of warning. Caffeine addiction can lead you to consume more than the recommended maximum dose of 400 mg of caffeine a day. While 400 milligrams of caffeine is quite a lot at first, it can be easy to slide past this boundary if or as you build up a tolerance — this is just a few standard energy drinks, or refilling your cup of coffee every few hours throughout your workday.

An 8 ounce cup of coffee (which is small) contains about 100 mg of caffeine. A 20 oz soda contains about 55 mg of caffeine.

It’s important to note that caffeine is technically a drug in the same sense as cocaine, amphetamines, and heroin. While caffeine is nowhere near as dangerous, they do have some things in common. In addition to addictive qualities, each of these drugs stimulates the same biochemicals in your brain and alters bodily function.

As a result of these changes, it’s possible to experience the following side effects:

Insomnia and Sleep Deprivation

Your body naturally produces a chemical called adenosine that slows down your heart rate, blood flow, muscle functions, and brain activity. Adenosine is the reason why you feel tired by the end of the day, and it helps you to fall asleep.

One of the primary effects of caffeine is that it blocks your adenosine receptors. You won’t feel the effects of adenosine as much, and you’ll feel awake, focused, and fresh throughout the day. While that’s good in the morning and afternoon, it can be a real problem at night or at bedtime.

Without adenosine to help your body slow down, it can be much harder to fall asleep and stay asleep. The next day you may be more tired and will probably drink more caffeine, which can create a vicious cycle of you tricking your body into thinking it’s not tired.

Worsens Anxiety

It’s unlikely that drinking caffeine will cause anxiety, but it does seem to make anxiety symptoms like restlessness, muscle tremors, irregular heartbeat, and nervousness much worse.

Anxiety is a condition where you feel intense dread or worry about everyday situations. You may perceive regular activities as threatening, triggering a “fight or flight” response even though there’s no real danger. Stress hormones increase.

Caffeine boosts your brain function so your mind is working much faster than usual, not to mention it literally stimulates your central nervous system. Stimulating an anxiety-prone brain and the already-restless CNS that’s paired with it can essentially magnify anxiety symptoms and keep them heightened until the caffeine wears off, even in the presence of anxiety medicine.

Digestive Problems

We’re not taking back our validation from earlier, but too much caffeine can be an issue for people with digestive problems such as irritable bowel syndrome. Even people without digestive conditions may experience diarrhea or other stomach issues with too many cups of joe.

Another issue is that caffeine is a diuretic; being under-hydrated can lead to constipation, as there isn’t enough fluid in your colon. You can probably see how it can be a problem to have an overactive colon that doesn’t have enough fluid to operate properly.

The Takeaway

Caffeine can provide benefits in small or manageable doses, but you need to be careful not to drink too much.

Moderation is key with caffeine, and it makes sense to keep your intake levels in check. When consumed in the proper amounts, caffeine can provide several benefits, helping you to stay focused, feel less tired, and even lose weight. Caffeine can even provide a positive boost to your sex life.

The tricky thing about caffeine is that it can be addictive and habit-forming. If you start to drink more than the recommended value of 400 milligrams a day, it may lead to health problems.

Make sure that you're only using caffeine as an occasional boost and not relying on it to function. If you’re a coffee addict, at least there’s always decaf.