From the Guidelines
Consuming 900 milligrams of caffeine per day makes muscle twitching almost certain for most individuals, with a likelihood of 8-10 out of 10, due to excessive stimulation of the central nervous system and increased release of calcium within muscle cells. This amount far exceeds the recommended daily limit of 400 mg for healthy adults, as stated in the Dietary Guidelines for Americans (DGA) 1. Caffeine at this high dosage can trigger involuntary contractions or twitches, particularly in the eyelids, hands, arms, legs, and feet.
Some key points to consider:
- The DGA recommends limiting caffeine intake to 400 mg/d, and pregnant women are advised to consume no more than 200 mg caffeine/d 1.
- Adolescent and child caffeine consumption should not exceed 2.5 mg · kg body weight–1 · d–1 1.
- High caffeine intakes, such as 900 mg/d, are associated with an increased risk of anxiety, insomnia, rapid heartbeat, digestive issues, and headaches, in addition to muscle twitching 1.
- To reduce muscle twitching, consider gradually decreasing your caffeine intake to below 400 mg daily, staying hydrated, ensuring adequate magnesium and potassium intake, and getting sufficient sleep.
It is essential to note that individual tolerance to caffeine can vary greatly, and some people may experience more severe side effects than others. If you're consuming this much caffeine regularly and experience persistent twitching, consult a healthcare provider as this could indicate caffeine toxicity or another underlying condition 1.
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 FDA drug label does not answer the question.
From the Research
Caffeine Intake and Muscle Twitching
The likelihood of experiencing muscle twitching with a caffeine intake of 900 milligrams (mg) per day can be assessed based on available research studies.
- Caffeine's effects on neuromuscular function have been studied, and it has been found that caffeine can increase muscle force and power output during all-out single multijoint movements 2.
- A study on the effects of caffeine on neuromuscular function found that caffeine increased maximal voluntary activation at a supraspinal level, but did not alter the force-EMG relationship or motor unit firing rates 3.
- Another study found that caffeine can potentiate twitch force and increase muscle power output during submaximal contractions, possibly by enhancing calcium release from the ryanodine receptor 4.
- However, high doses of caffeine (9 mg/kg) have been found to increase the frequency of adverse side effects, including muscle twitching 2.
- The exact dose of caffeine that would cause muscle twitching is not well established, but it is likely that high doses (such as 900 mg) would increase the risk of twitching.
Assessment of Twitching Risk
Based on the available evidence, it is difficult to provide a precise estimate of the risk of muscle twitching with a caffeine intake of 900 mg per day.
- However, considering the potential for caffeine to increase muscle force and power output, as well as the risk of adverse side effects at high doses, it is possible that muscle twitching could occur at this level of intake.
- A study on the effects of caffeine on fatigue and muscle function found that caffeine can convert activity-induced shortening of half-relaxation times into prolongations, which could potentially contribute to muscle twitching 5.
- Overall, while the exact risk of muscle twitching with 900 mg of caffeine per day is unclear, it is likely that this level of intake would increase the risk of twitching, particularly in sensitive individuals.
Rating of Twitching Risk
Based on the available evidence, a rating of the risk of muscle twitching with 900 mg of caffeine per day could be as follows: