From the FDA Drug Label
Signs and symptoms reported in the literature after caffeine overdose in preterm infants include ... fine tremor of the extremities, hypertonia, opisthotonos, tonic-clonic movements, ... The chances of muscle twitching after consuming 500 milligrams of caffeine and 2 teaspoons of salt are high, around 8-9 out of 10, as muscle twitching can be associated with fine tremor of the extremities, hypertonia, and tonic-clonic movements, which are reported signs and symptoms of caffeine overdose 1.
From the Research
The chances of experiencing muscle twitching after consuming 500 milligrams of caffeine and 2 teaspoons of salt would be approximately 8 out of 10. This combination creates a high risk for muscle twitching due to the significant amount of caffeine, which is well above the recommended daily limit of 400mg for most adults, as seen in studies such as 2 where high doses of caffeine were associated with increased muscle force and power output. Caffeine stimulates the central nervous system and can cause increased neuromuscular activity, leading to twitching, as supported by the findings of 3 which demonstrated that caffeine potentiates twitch responses in both fast-twitch and slow-twitch muscles. Additionally, 2 teaspoons of salt (about 4,800mg of sodium) is double the daily recommended sodium intake, which can disrupt electrolyte balance, as noted in the context of severe caffeine overdose in 4 where hypokalemia and hyponatremia were observed. The combination may cause dehydration and electrolyte imbalances that further contribute to muscle twitching. Individuals with pre-existing conditions like anxiety disorders, heart problems, or kidney issues would be at even higher risk, as suggested by the potential for adverse side effects at high caffeine doses in 2. To reduce these symptoms, consider reducing caffeine intake to below 200mg per day, limiting sodium to less than 2,300mg daily, staying well-hydrated, and allowing the body time to metabolize these substances before physical activity or sleep. It's also worth noting that the most recent and highest quality study, 5, found that high acute doses of caffeine did not improve muscle strength nor muscle endurance in athletes habituated to this substance, suggesting that the effects of caffeine on muscle twitching may be more related to its stimulatory effects on the central nervous system rather than any direct effect on muscle performance. However, the specific interaction between caffeine and salt consumption in relation to muscle twitching is not directly addressed in the provided studies, but based on the known effects of each substance, the risk of muscle twitching is likely increased. Given the potential risks, it is prudent to exercise caution and consider the individual's overall health and sensitivity to caffeine and sodium when consuming these substances. Key factors to consider include the amount of caffeine and salt consumed, individual tolerance, and the presence of any underlying health conditions that may exacerbate the effects of these substances. By understanding these factors and taking steps to mitigate potential risks, individuals can make informed decisions about their consumption of caffeine and salt. Ultimately, prioritizing morbidity, mortality, and quality of life outcomes suggests that minimizing the intake of these substances, especially in combination, is the most prudent approach.