Coffee is a good way to wake up and stay more alert during the day. However, the caffeine in coffee can cause issues in the body over time. Some vulnerable groups or people with certain health conditions may want to avoid coffee for their own safety.
People who are pregnant or breastfeeding should not drink coffee. You also may want to avoid coffee if you have sleep disorders, frequent migraines, anxiety, GERD/ulcers, take other stimulants, have high blood pressure, or are a child or teenager. Coffee could make these conditions worse over time.
It may be hard to cut coffee out of your diet if you’re used to drinking it every day. However, if you experience any of the previous health problems, you might find that drinking less caffeine can make a big difference in your life.
Coffee’s Main Effects on the Body

If you drink caffeine you will usually be able to feel its effects for the next 4-6 hours. It will stimulate your nervous system which can give you more energy and help you feel more awake. However, it can also cause heartburn or stomachache because it increases the release of acid from your stomach. It also interferes with the levels of salt, water, and calcium in your body.
Pregnancy and Breastfeeding
If you are pregnant or breastfeeding, it is okay to take about one cup a day, but you may want to think about stopping your intake of coffee and caffeine overall. During this time, a mother is sharing her nutrients with her child. So if you intake a lot of caffeine, the child is intaking a lot as well, (but still not as much as you).
A single cup is recommended because it has time to metabolize before getting to the child during breastfeeding (Source). A good way to begin limiting your coffee intake is limiting it to two cups a day, then one, and then none.
Sleep Disorders
In a study done on the effects of caffeine intake before sleep, they found that if you intake caffeine 6 hours before you normally go to sleep, it can affect the kind of sleep you get. The study talked about how the first two stages of sleep before REM sleep were disrupted. REM sleep was not disrupted with an intake of caffeine 6 hours before sleeping. You can review the whole study here.
Although Caffeine may help beat sleepiness, this effect is only temporary and does not replace the benefits of a good night’s sleep.
Source: https://www.sleephealthfoundation.org.au/caffeine-and-sleep.html
A lot of people use caffeine to prevent themselves from falling asleep if they need to get up early or pull an all-nighter. I definitely have an energy drink some mornings while I am at work to stay awake.
However, in some cases, caffeine can cover sleep apnea in the body. A common symptom of sleep apnea is tiredness during the day; which people use caffeine to help them stay awake during the day.

Drinking caffeine can also cause insomnia. Depending on how often you take it and when you take it, caffeine can overtake the time used for sleep. Even if you took caffeine a couple of hours ago, it can still be in your bloodstream and keep you up at night. If you already have insomnia, it is highly recommended to avoid caffeine to prevent further disruption to your sleep.
GERD/ulcers
GERD is the backup of stomach acid in the esophagus. This erodes the esophagus which causes ulcers or open sores. You can tell if you have ulcers if certain foods begin to hurt on the way down to your stomach. Caffeine is a major pain causer if you have ulcers and can make matters worse. Do not drink caffeinated drinks at this time. Let your body heal and in some cases quit altogether to prevent further problems. (Source).
High Blood Pressure
If you have high blood pressure, caffeine can affect your body based on how often you consume it. If you don’t usually drink caffeinated drinks, it can increase your blood pressure. If you have high blood pressure after your normal Starbucks run, it may be high because of the caffeine you just drank. A good way to test yourself is to check your blood pressure before drinking and then again after you had a cup of coffee to see the change. If you have high blood pressure, make sure to check with your doctor if you should drink coffee or caffeine.
Other Negative Effects
Caffeine affects the body in many ways. The main effect is that it stimulates the body. To do this, the caffeine blocks the body’s ability to feel tired. Adenosine is a sleep-promoting chemical that builds up in the body once we run out of energy. But since caffeine blocks the body’s ability to produce that chemical, when you drink caffeine you will still be tired after its effects wear off because it only blocked the feeling instead of getting rid of it. (Source: https://www.sleepscore.com/learn-about-adenosine/)
Caffeine is also very addictive, making it difficult to stop consuming it, even if you need to stop for health reasons. I have had plenty of roommates who say it is not an addiction, but then when they go even a day without their energy drink they get massive headaches.
This is another major problem that comes with caffeine, not consuming it can cause headaches and an increase in anxiety after a while because your body starts to crave it and has withdrawals without it. To prevent possible addiction early on, it is recommended to keep caffeine and coffee from children and teens.

There are some people who can develop a tolerance to the caffeine in coffee. They can start with about a cup a day to keep them awake, but then after a couple of months, they need two cups to stay awake. This can depend from person to person. Some people only need a shot of espresso and they will be jittery the whole day. Whatever your tolerance is, try your best to limit your intake because the more you take can increase the various effects we have discussed.
Overall, in all of these cases, or in your daily life, limit your coffee intake and make sure to talk to your doctor about what works best for you.