How Much Caffeine Is Too Much?

Waseem Hussain, MD, is a primary care physician at Luminis Health with expertise in family medicine, including neurologic, pulmonary and cardiac diseases, as well as diabetes and gynecologic care.

Whether it’s coffee to start the day, a cold soda to revive the afternoon, or a beloved pumpkin spice latte to embrace the season, caffeine is a popular pick-me-up for many people. However, while these caffeinated drinks can provide a much-needed boost, excessive consumption can have negative effects on your health. In rare instances, it can even be fatal. That’s why it’s important to know the facts.

What is caffeine?

Caffeine is a naturally occurring stimulant that affects your central nervous system, helping you feel more awake and alert. It’s found in coffee beans, tea leaves, kola nuts, yerba mate, guarana berry and cacao beans.

What is a safe limit for caffeine?

According to the Food and Drug Administration (FDA), most healthy adults can consume 400 milligrams (mg) of caffeine a day without any dangerous effects. If you are pregnant, the American College of Obstetricians and Gynecologists suggests keeping your caffeine intake below 200 milligrams a day.

Caffeine levels in beverages vary, making it easy to overconsume. Here are typical ranges:

• An 8-ounce cup of coffee: 80 to 100 milligrams.
• An 8-ounce cup of green or black tea: 30 to 50 milligrams.
• A 12-ounce can of caffeinated soda: 30 to 46 milligrams.
• An 8-ounce energy drink: 40 to 300 milligrams.

Include all sources of caffeine in your total intake, such as chocolate, baked goods and some medications. Even decaffeinated drinks may have 2 to 15 milligrams of caffeine. Check package labels for caffeine content.

What are some side effects of too much caffeine?

Too much caffeine can cause:

• Agitation or irritability
• Fast heart rate
• Feeling anxious or restless
• Increased urination, leading to dehydration
• Insomnia
• Muscle twitches
• Nausea or upset stomach

Can you overdose on caffeine?

Consuming around 1,200 mg of caffeine at once can cause toxic effects, according to the FDA. While rare, it is possible to overdose on caffeine, which can lead to death. Severe side effects include:

• Cardiac arrest
• Disorientation
• Hallucinations
• Irregular heartbeat
• Muscle breakdown
• Seizures

Overdose risk increases with dietary liquid or powdered caffeine supplements, which often contain high concentrations.

Why should you space out your caffeine intake?

Caffeine takes 45 to 60 minutes to kick in, and its effects last three to five hours. Consuming too much caffeine at once or too close together can lead to dangerous side effects. Limit intake to 400 mg a day and space out consumption to reduce risk. Avoid caffeine at least six hours before bedtime to prevent sleep disruption.

Who should avoid caffeine?

Some medical conditions increase the risk of caffeine side effects. Consult your doctor if you have:

• Cardiovascular disease
• High blood pressure
• Severe anxiety
• Peptic ulcer disease or GERD
• Liver or kidney disease
• Seizures

What’s the bottom line?

People experience caffeine differently. If you have side effects, see the specialist team at Luminis Health to understand your sensitivity to caffeine.

Waseem Hussain, MD, is a primary care physician at Luminis Health with expertise in family medicine, including neurologic, pulmonary and cardiac diseases, as well as diabetes and gynecologic care.