How Many Cups of Coffee Is Too Much?

It's generally safe to drink about four 8-ounce (oz) cups of coffee, which contain about 400 milligrams (mg) of caffeine, per day. More than this amount might be too much. You may feel anxious, jittery, or nauseous if you drink too much coffee.

Drinking coffee has some benefits. Caffeine has antioxidants and anti-inflammatory compounds that may protect against Alzheimer's disease, heart disease, and liver disease.

How Much Caffeine Is in a Cup of Coffee?

Caffeine is a substance that's found in more than 60 plants, such as coffee beans and tea leaves. It tastes bitter and is an active ingredient in coffee. There are about 95 to 200 mg of caffeine in an 8-oz cup of coffee.

Side Effects of Too Much Coffee

Consuming the amount of caffeine in your regular coffee habit is likely safe. The side effects of too much caffeine may begin to develop after consuming moderate amounts. The amount of caffeine needed to cause unwanted side effects varies: People can have different levels of sensitivity to caffeine.

Moderate side effects of too much caffeine include:

• Facial flushing
• Feelings of anxiety or restlessness
• Having to urinate more frequently
• Increased heart rate
• Stomach upset

More severe side effects after significant amounts of caffeine can be dangerous. These side effects include feeling disorientated and experiencing hallucinations.

Risks

Up to 400 mg of caffeine—about four 8-oz cups of coffee—per day is typically safe for adults. Drinking more than this amount can increase the risk of health complications.

Some people are more sensitive than others to the effects of caffeine. Consuming a lot of coffee can also negatively affect heart health and pregnancy. 

Caffeine Sensitivity

You might feel jittery, irritable, or nauseous if you drink a lot of coffee. Some people may be more sensitive to caffeine than others.

A study published in 2019 looked at what participants had a specific gene variant called CYP1A2. This variant helps people metabolize caffeine faster than those without it. People with the gene can't safely drink more coffee than those who don't.

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 can cross the placenta and have negative effects on fetal development during pregnancy. It's a stimulant that raises heart rate and metabolism, which can affect the fetus. Research has shown that drinking too much coffee during pregnancy can increase the risk of low birth weight, miscarriage, and stillbirth.

The American College of Obstetricians and Gynecologists (ACOG) advises that you limit your caffeine intake if you're pregnant. Consume no more than 200 mg of caffeine or one 12-oz cup of coffee per day.

Benefits of Drinking Coffee

Research has found numerous health benefits of drinking coffee. Coffee is a source of antioxidants, which can help lower the risk of several diseases.

Some evidence suggests that coffee may lower the risk of the following:

• Alzheimer's disease: This is the most common type of dementia. Research has shown that the antioxidants in coffee may protect the brain against Alzheimer's disease.
• 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 suggests that one to three cups of coffee per day may reduce the risk of high blood pressure.
• Liver disease: Research has found that 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.

Tips for Consuming Caffeine

It's generally safe to drink no more than four 8-oz cups of coffee per day. You may reduce your caffeine intake if you have:

• Acid reflux or stomach ulcers
• Chronic headaches
• Fast or irregular heart rhythm
• High blood pressure
• Painful, lumpy breasts
• Sleep problems
• Stress or anxiety

Make sure to slowly reduce your caffeine intake to avoid caffeine withdrawal. Symptoms can include headaches, irritability, and nausea.

A Quick Review

Drinking coffee is generally safe if you do so in moderation. You can safely drink about 400 mg of caffeine, or four 8-oz cups of coffee, per day. Any more than this amount may be too much. You may develop side effects like anxiety and nausea if you drink too much coffee. Other health risks include increased blood pressure and pregnancy complications.