It’s generally safe to drink four 8-ounce (oz) cups of coffee per day, or about 400 milligrams (mg) of caffeine. If you drink more than that, you may feel anxious, jittery, or nauseous. Consuming too much coffee can also negatively affect heart health and pregnancy.
That said, there are health benefits to drinking coffee. Caffeine has antioxidants and anti-inflammatory compounds that may protect against Alzheimer’s disease, heart disease, and liver disease.
Some people are more sensitive to caffeine than others, so the amount of caffeine needed to cause unwanted side effects varies.
Moderate side effects include:
- Facial flushing
- Anxiety or restlessness
- Having to urinate more frequently
- Increased heart rate
- Stomach upset
More severe side effects, usually from very high caffeine intake, include:
- Feeling disoriented
- Hallucinations
While moderate coffee consumption is safe, drinking more than four 8-oz cups daily can increase the risk of certain health complications.
Caffeine Sensitivity
If you drink too much coffee, you might feel jittery, irritable, or nauseous.
Some people may be more sensitive to these effects than others due to variants in the CYP1A2 gene, which controls how fast you metabolize caffeine.
Heart Disease
Heart disease is the leading cause of death worldwide. A study published in 2019 found that drinking six or more cups of coffee per day may increase the risk of heart disease by up to 22%. Large quantities of coffee can cause high blood pressure, which is a risk factor for heart disease.
Pregnancy Complications
Caffeine raises heart rate and metabolism, which can affect the fetus during pregnancy. This stimulant can cross the placenta and may have negative effects on fetal development.
Research has shown that drinking too much coffee during pregnancy can increase the risk of:
American College of Obstetricians and Gynecologists (ACOG) recommendation: Pregnant people should consume no more than 200 milligrams of caffeine daily (the equivalent of one 12-oz cup of coffee).
Coffee contains antioxidant and anti-inflammatory compounds that may reduce your risk of several conditions, including:
- Alzheimer’s disease: This is the most common type of dementia. Research has shown that the antioxidants in coffee may protect the brain against this condition.
- Cancer: Coffee has been shown to reduce the risk of some cancers, such as prostate and endometrial cancer. It may also protect against melanoma, the most severe type of skin cancer.
- Heart disease: Coffee is a source of phenols. These compounds have antioxidant and anti-inflammatory properties that can protect against heart disease. Some evidence also suggests that 1-3 daily cups of coffee may reduce the risk of high blood pressure.
- Liver disease: Coffee may protect against cirrhosis (scarring of the liver) and liver cancer. The compounds found in coffee may decrease inflammation and support liver function.
- Parkinson’s disease: Some evidence suggests that caffeine may block adenosine A2A receptors, which are expressed in people with Parkinson’s disease.
It’s generally safe to drink up to four 8-oz cups of coffee per day. Consider reducing your caffeine intake if you have:
Consider reducing your caffeine intake slowly to avoid caffeine withdrawal. Withdrawal symptoms can include:
- Headaches
- Irritability
- Nausea
Drinking coffee is generally safe if you do so in moderation. You can drink four 8-oz cups, or about 400 milligrams of caffeine, per day. Any more than this amount may lead to side effects like anxiety and nausea. Other health risks include pregnancy complications and an increased risk of heart disease.
