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How to recognize caffeine overdose

Carreon, Christian “CJ” BSN, RN; Parsh, Bridget EdD, MSN, RN, CNS

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doi: 10.1097/01.NURSE.0000553278.11096.86
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CAFFEINE CAN BE USED to improve cognitive alertness, reduce fatigue, and enhance physical endurance.1 When consumed in moderation, caffeine, or 1,3,7-trimethylxanthine, can offer a variety of other benefits. For example, moderate caffeine consumption (4 to 5 cups of coffee or less each day) is correlated with a reduced risk of cardiovascular disease, type 2 diabetes, and Parkinson disease in healthy adults.2 It is known to treat apnea of prematurity in neonates, various headache disorders, and can be used as a mild diuretic.3,4 Caffeine has also been shown to promote lung function in people with chronic pulmonary diseases and may even play a role in reducing the risk of atrial fibrillation.4,5

However, consuming caffeine in extremely high doses can lead to overdose. This article examines how nurses can recognize the signs and symptoms of caffeine overdose and educate patients on how to prevent it.

Hidden dangers

While coffee, tea, energy drinks, and other beverages account for most caffeine consumption, caffeine can be taken as a tablet and even inhaled for a quicker “energy boost.”6 (See How much caffeine are you consuming?) Further, powdered or liquid forms of highly concentrated caffeine have been marketed directly to consumers as dietary supplements and sold in bulk packaging, but they pose a high risk of being erroneously used at excessive and potentially dangerous doses. One teaspoon of pure powdered caffeine is equivalent to 20 to 28 cups of coffee, and these products have been linked to at least two deaths in otherwise healthy individuals.7 In 2018, the US Food and Drug Administration issued a guidance clarifying that these products are considered unlawful when sold in bulk quantities directly to consumers.8 The increasing popularity and enhanced potency of caffeine predispose consumers to very serious—or even fatal—health and safety risks.9

Caffeine overdose and ensuing withdrawal can take a significant physical and psychological toll, yet caffeine consumption remains popular.10 One survey showed that more than 80% of student athletes reported using energy drinks, and 64% reported using dietary supplements to enhance athletic performance.1

The Diagnostic and Statistical Manual of Mental Disorders, 5th edition, recognizes four caffeine-related diagnoses: caffeine intoxication, caffeine withdrawal, other caffeine-induced conditions such as anxiety and sleep disorders, and unspecified caffeine-related disorder.11 Moderate intake of caffeine is not associated with serious cardiovascular or neuroendocrine effects, but rather mild, transient effects such as increased heart rate and increased BP.12

How much caffeine are you consuming?21-24

Because of their smaller size and decreased caffeine tolerance due to lower habitual intake, children and teens may be more susceptible to the effects of caffeine.13 Signs and symptoms of possible ingestion by infants include nausea and muscular rigidity. Although the FDA does not have established guidelines for children and adolescents, the American Academy of Pediatrics discourages the consumption of caffeine and other stimulants.1 Infant consumption of caffeine should be completely avoided.9

Clinical manifestations

Caffeine is a potent antagonist of central and peripheral nervous system adenosine receptors, thereby stimulating the release of excitatory neurotransmitters.14 Blocked adeno-sine receptors and increased sympathetic nervous system activity can lead to a heightened sense of alertness related to bronchospasm, increased smooth muscle contraction, and increased heart rate.4

Other neurovascular changes can occur at higher serum concentrations (over 25 mcg/mL).12 Caffeine can block the enzyme monoamine oxidase, which leads to increased levels of epinephrine, dopamine, and glutamate in the body. These neurotransmitters stimulate direct and indirect neuroendocrine changes including generalized vasoconstriction, increased heart rate, hypokalemia, and increased sodium and water excretion.9,12 At high levels, caffeine binds to ryanodine receptors, which increases serum calcium levels.4 Both increased calcium availability and low serum potassium levels may lead to cardiac dysrhythmias with toxic levels of caffeine.4,12

Moderate toxicity can cause restlessness, tremors, anxiety, mood changes, and gastrointestinal discomfort (such as vomiting).1 Very high doses of ingested caffeine (more than 6 mg/kg) can decrease both physical and cognitive performance and induce severe gastrointestinal distress.15 Extremely high blood levels (up to 150mg/kg) of caffeine can cause changes including hypokalemia, ventricular dysrhythmias, hypotension, rhabdomyolysis, and death.1 Blood caffeine concentrations around 150 mg/kg of body weight can be fatal. This is equivalent to approximately 50 caffeine pills or 1 tablespoon of powdered caffeine.1

Patients may also present with signs and symptoms such as recurrent seizures, hypertonicity, tachycardia, renal failure, psychosis, or hyperglycemia with acidosis.1 Deaths from caffeine overdose can result from cardiac dysrhythmias or be secondary to renal complications related to rhabdomyolysis.1 A dipstick urinalysis and creatine kinase level can assist with diagnosing rhabdomyolysis. Also anticipate a complete blood cell count to rule out infection, serum electrolytes to monitor for hypokalemia, and toxicity screening to rule out ingestion of other substances. Serum caffeine levels do not influence management, but a theophylline level (a metabolite of caffeine) can help confirm caffeine toxicity.16


Because no antidote or reversal agent is available for caffeine intoxication, management depends on signs and symptoms.17 A classic caffeine overdose treatment follows the three Bs: bolus, benzodiazepines, and beta-blockers. Use bolus crystalloid for significant gastrointestinal losses, diuresis, and any hypotension the patient has. Treat with benzodiazepines for seizure activity and to decrease the catecholamine release contributing to cardiac symptoms. Use a beta-blocker to reduce the unopposed beta agonism of the catecholamine release.18 Assess the patient's respiratory, cardiovascular, and neurologic status frequently.

Although caffeine can act as a bronchodilator, one study found that patients age 12 to 18 years complained of headaches, difficulty breathing, and urinary frequency.19 Complications can arise from cardiac dysrhythmias, so patients should have continuous cardiac monitoring. Provide supplemental oxygen as prescribed. Patients experiencing seizures, hemodynamic instability, or altered mental status may require endotracheal intubation.16

Assess the patient's Glasgow Coma Scale score and mental status frequently. If the ingestion was recent, such as within the hour, anticipate using activated charcoal as a possible intervention.

Patients may appear anxious, stressed, or angry. Inform them that treatment of caffeine overdose varies depending on their presenting signs and symptoms.17 Benzodiazepines may be given for anxiety or seizure activity.16 Assess vital signs and blood glucose levels frequently to monitor cardiac stability and address other factors that may contribute to clinical decompensation.16

Nursing considerations

Nurses should be aware of the rising popularity of highly caffeinated products and the nonspecific signs and symptoms patients may present with.7 It is also important to recognize high-risk populations prone to caffeine toxicity, particularly athletes.9 Teens and young adults also are vulnerable because they may be aware of the perceived benefits of these products but not the risks.7 Behavioral health patients, especially those with undiagnosed or poorly controlled behavioral health disorders such as depression or bipolar disorder, are another high-risk population prone to caffeine overdose.9 Patients with intentional caffeine overdose should receive a psychiatric consultation.16

Patients and families should be informed about the risks of highly concentrated products and excessive amounts of caffeine intake.7 Parents, especially parents of athletes, and coaches should be instructed to counsel against use of energy drinks before or during sports activities despite popular belief that it will enhance performance.20 Combining energy drinks with alcohol, which has become a common practice, should be discouraged as well.20 This can lead to fatal consequences because caffeine can mask alcohol intoxication.8

Educating adult and adolescent patients about the dangers of caffeine ingestion can be difficult because caffeine is an accepted “drug” in society. Assess your patient's knowledge of the effects of all legal drugs, including caffeine, so you can fill in the gaps. Coaches, parents, and students need to understand the potential grave consequences from overdose of caffeine.

Caffeine is not a benign substance, especially when combined with other substances such as certain medications and alcohol. Nurses must quickly identify signs and symptoms associated with caffeine overuse and overdose and educate patients on how to prevent it.


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          caffeine overdose; coffee; energy drinks; liquid caffeine; pure powdered caffeine

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