From the Guidelines
Consuming 2000 mg of caffeine poses an extremely high risk of experiencing mild twitching, along with other serious side effects, due to its excessive stimulation of the nervous system. This amount far exceeds the recommended safe limit of 400 mg per day for healthy adults, as suggested by the Dietary Guidelines for Americans (DGA) 1. At 2000 mg, caffeine can cause not only muscle twitches but also more dangerous symptoms, including irregular heartbeat, severe anxiety, panic attacks, tremors, nausea, vomiting, and in extreme cases, seizures or cardiac events.
According to a recent study published in Advances in Nutrition, the evidence generally supports that consumption of ≤400 mg caffeine/d in healthy adults is not associated with adverse cardiovascular effects, behavioral effects, reproductive and developmental effects, acute effects, or bone status 1. However, consuming 2000 mg of caffeine would significantly overstimulate the nervous system, leading to these neurological and muscular effects.
The American population's mean caffeine intake is approximately 165 mg/d, with coffee being the primary source of caffeine (64%; 105.4 mg/d) 1. The study also notes that children and adolescents metabolize caffeine more rapidly than adults, and high caffeine intakes (e.g., >5 mg · kg body weight–1 · d–1) were associated with an increased risk of anxiety and withdrawal symptoms in children 1.
Given the potential risks associated with high caffeine intake, it is strongly advised to immediately reduce caffeine consumption to the recommended safe limit and seek medical attention if currently consuming 2000 mg of caffeine. Even individuals with high caffeine tolerance would experience adverse effects at this dose, and gradual reduction rather than sudden cessation would be recommended to avoid withdrawal symptoms.
From the FDA Drug Label
Following overdose, serum caffeine levels have ranged from approximately 24 mg/L (a post marketing spontaneous case report in which an infant exhibited irritability, poor feeding and insomnia) to 350 mg/L. Serious toxicity has been associated with serum levels greater than 50 mg/L Signs and symptoms reported in the literature after caffeine overdose in preterm infants include fever, tachypnea, jitteriness, insomnia, fine tremor of the extremities, hypertonia, opisthotonos, tonic-clonic movements, nonpurposeful jaw and lip movements, vomiting, hyperglycemia, elevated blood urea nitrogen, and elevated total leukocyte concentration
The FDA drug label does not answer the question.
From the Research
Caffeine Intake and Mild Twitching
- The risk of experiencing mild twitching with a caffeine intake of 2000 milligrams (mg) is not directly addressed in the provided studies.
- However, study 2 mentions that excessive caffeine consumption can cause negative health consequences such as psychomotor agitation, insomnia, headache, gastrointestinal complaints, and adverse effects on the central nervous system.
- Study 3 suggests that consumption of up to 400 mg caffeine/day in healthy adults is not associated with overt, adverse cardiovascular effects, behavioral effects, reproductive and developmental effects, acute effects, or bone status.
- Study 4 reports that one-third (34.4%) of caffeine consumers ingested caffeine above the adverse effect level (3 mg/kgbw-1/day-1) and 14.3% above the safe limit (400 mg/day-1), with most consumers (84.7%) reporting experiencing at least one 'adverse symptom' post-caffeine consumption.
- Study 5 describes a case of fatal caffeine poisoning with an estimated intake of 10,000 mg, which is significantly higher than the 2000 mg in question.
- Study 6 reports a case of acute caffeine overdose in a one-year-old child with an estimated intake of 200-300 mg/kg, resulting in ventricular arrhythmias, seizures, metabolic disturbances, and severe pulmonary edema.
- While these studies do not provide a direct answer to the question, they suggest that high levels of caffeine consumption can lead to adverse effects, including those related to the central nervous system, which may include mild twitching 2, 3, 4, 6.