What Are the Signs of Caffeine Overdose?

Caffeine is a stimulant that triggers the central nervous system. It is the most widely consumed psychoactive substance in the world. In moderate doses, caffeine makes us feel good. But in amounts above 400 milligrams per day, caffeine overdose is possible.

This article reviews caffeine consumption guidelines, high-caffeine drinks, and what to do if you've had too much caffeine. 

Recommended Dosage of Caffeine

Consuming less than 400 milligrams (mg) of caffeine per day is considered a safe dosage for most healthy adults without any medical conditions. The U.S. Food and Drug Administration (FDA) considers excessive caffeine consumption anything above 400 mg/day.

Children under age 12 should avoid caffeine. Teenagers should limit their caffeine intake to about 100 mg per day. Kids and teens should also avoid consuming energy drinks.

Sources of Caffeine

Over 60 plants contain caffeine. The most common natural caffeine sources are:

• Coffee beans
• Tea leaves
• Kola nuts (used in colas)
• Cacao pods (used in chocolate)

Some caffeine is made artificially and added to soft drinks or other products.

A breakdown of caffeine measurements per source is provided below.

Risks and Benefits of Caffeine

Caffeine increases awareness, reduces fatigue, and lifts mood. It can also improve physical and cognitive performance. Low to moderate doses (40 mg to 300 mg) can improve the following:

• Alertness
• Attention
• Executive function
• Memory
• Reaction times
• Vigilance

In moderate to high doses (200 mg to 400 mg), caffeine can improve athletic performance. Athletes who consume very little caffeine (< 40 mg/day) on a regular basis feel the effects more on game day.

Sports-related benefits of caffeine include:

• Endurance and stamina
• Hand-eye coordination
• Peripheral awareness
• Faster sprints

Caffeine consumption comes with risks. Too much caffeine instantly undoes all of its benefits. Although drinking too much coffee or tea can be risky, energy drinks and highly concentrated caffeine in dietary supplements (pills, powders, liquid shots) present the biggest overdose risk.

One teaspoon of pure powdered caffeine can equal 28 cups of coffee. The recommended dose of 1/16 teaspoon is tiny and difficult to measure accurately. Accidental measurement errors are common. A simple mistake of using 1/4 teaspoon could result in a toxic dose being consumed.

Caffeine can be lethal, but fatalities from caffeine are extremely rare. A lethal dose of caffeine is about 5 to 10 grams (5,000 to 10,000 mg) or 150 to 200 mg per kilogram of body weight.

Sub-lethal caffeine overdose may cause symptoms such as chills, flushing, headache, nausea, heart palpitations, and tremors. Excessive consumption of products containing caffeine can also cause rhabdomyolysis and acute kidney injury.

When someone dies from a caffeine overdose, the cause of death is often described as ventricular fibrillation (erratic heartbeat).

Side Effects of Too Much Caffeine

Signs of too much caffeine include anxiety, feeling jittery, insomnia, GI issues, and having your heart race over 100 beats per minute (tachycardia). In rare cases, caffeine toxicity results in death. Individual responses to any dose of caffeine can vary significantly.

Caffeine overdose can cause the following symptoms:

• Anxiety
• Breathing trouble
• Chest pain
• Convulsions
• Diarrhea
• Heart palpitations
• Increased thirst/urination
• Irritability
• Lightheadedness or dizziness
• Nausea or vomiting
• Paresthesia (tingling, pins and needles feeling)
• Profuse perspiration
  
• Rhabdomyolysis (kidney-injuring syndrome)
• Sudden cardiac arrest
• Tremors or shakiness
  

Diagnosis

Exactly how much caffeine is dangerous varies from person to person. If you or someone else accidentally consumes too much caffeine and has overdose symptoms, contact Poison Control right away. Call 911 in the case of emergencies.

Preventing Caffeine Overdose

Educating yourself about how much caffeine is in everything you eat, drink, or swallow is the best way to prevent caffeine overdose.

Caffeine is often hidden in products. Read labels closely and keep tabs on how many milligrams of caffeine you consume each day.

Certain medications increase the risk of caffeine toxicity, including:

• Appetite suppressants
• Bronchodilators
• Decongestants
• Some over-the-counter pain relievers

Accidental caffeine overdose can occur if these are taken with daily amounts of coffee, tea, or soda.

Speak with a healthcare provider about how much caffeine is in the medication you take. Cut back on typical daily intake of caffeine-containing products while taking these medicines to avoid caffeine overdose.

Summary

Overdosing on caffeine is rare, but accidental overdoses happen. The recommended amount of caffeine that adults can consume for their health and safety is approximately 400 milligrams (mg) per day. Children under 12 should avoid caffeine. Teens should limit caffeine to about 100 mg per day.

Energy drinks are one of the most common ways to accidentally overdose on caffeine. Read energy drink labels closely and calculate how much caffeine is in each container. Serving sizes and caffeine per fluid ounce can vary greatly. Call Poison Control or 911 immediately in caffeine-related emergencies.

A Word From Verywell

People of all ages are at risk of caffeine overdose. If you want to cut back on caffeine to lower your risk, there are healthy alternatives. Eating a nutritious diet and getting enough sleep will give you the energy to power through the day with less caffeine. Anytime you cut back on your daily caffeine intake, do so gradually. Caffeine withdrawal is avoidable if you don't go cold turkey.