From the Guidelines
Muscle twitches caused by high doses of caffeine are typically mild to moderate in severity and temporary, resolving once caffeine levels in the body decrease. These twitches, also called fasciculations, occur because caffeine stimulates the central nervous system and can increase nerve excitability, leading to involuntary muscle contractions. According to a recent study 1, consuming more than 400mg of caffeine daily (equivalent to about 4 cups of coffee) increases the risk of these symptoms. While uncomfortable, caffeine-induced muscle twitches are rarely dangerous for most healthy individuals.
To reduce these symptoms, it is recommended to decrease caffeine intake gradually rather than suddenly to avoid withdrawal symptoms, stay hydrated, and ensure adequate intake of electrolytes like magnesium and potassium. People with certain medical conditions such as anxiety disorders, heart problems, or seizure disorders should be particularly cautious with caffeine consumption as it may exacerbate their conditions and potentially cause more severe neuromuscular symptoms. A study on caffeine consumption found that intake 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.
Some key points to consider:
- Caffeine stimulates the central nervous system, increasing nerve excitability and leading to involuntary muscle contractions 1
- Consuming more than 400mg of caffeine daily increases the risk of muscle twitches 1
- Decreasing caffeine intake gradually, staying hydrated, and ensuring adequate electrolyte intake can help reduce symptoms
- Certain medical conditions, such as anxiety disorders or heart problems, may be exacerbated by caffeine consumption 1
- Healthy adults can generally consume up to 400mg of caffeine daily without adverse effects 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, nonpurposeful jaw and lip movements, ... The severity of muscle twitches caused by a high dose of caffeine can be severe, as evidenced by symptoms such as:
- Fine tremor of the extremities
- Hypertonia
- Tonic-clonic movements These symptoms suggest that the muscle twitches can be intense and potentially debilitating. 2
From the Research
Severity of Muscle Twitches
The severity of muscle twitches caused by a high dose of caffeine can vary depending on several factors, including the amount of caffeine consumed and individual sensitivity.
- Studies have shown that high doses of caffeine can cause severe muscle twitching, as well as other symptoms such as agitation, tremor, and vomiting 3.
- In one case study, a 20-year-old woman experienced severe agitation, tremor, and vomiting after ingesting a large amount of concentrated caffeine, and subsequently developed life-threatening cardiac dysrhythmias 3.
- Another study found that caffeine can cause coronary artery vasospasm, which can lead to chest pain and other cardiac symptoms 4.
- However, other studies have found that moderate caffeine consumption does not typically cause significant muscle twitching or other adverse effects in most people 5.
- In terms of the specific effects of caffeine on muscle twitching, one study found that caffeine can convert activity-induced shortening of half-relaxation times into prolongations in both fast-twitch and slow-twitch muscles 6.
Factors Influencing Severity
The severity of muscle twitches caused by caffeine can be influenced by several factors, including:
- Dose: High doses of caffeine are more likely to cause severe muscle twitching and other adverse effects.
- Individual sensitivity: Some people may be more sensitive to the effects of caffeine and experience more severe muscle twitching at lower doses.
- Other health conditions: Certain health conditions, such as anxiety or heart problems, may increase the risk of adverse effects from caffeine consumption.
- Caffeine can also interact with other substances, such as diazepam, and counteract their effects 7.