Which muscle groups are most likely to twitch first in cases of caffeine toxicity?

From the Guidelines

In cases of caffeine toxicity, the facial muscles, particularly those around the eyelids, and small muscles of the hands are typically the first to experience twitching. These muscle groups are especially sensitive to caffeine's stimulatory effects on the central nervous system, as evidenced by the study on neonatal drug withdrawal 1. According to the provided evidence, caffeine toxicity can cause jitteriness, vomiting, bradycardia, and tachypnea, with onset at birth and duration of 1-7 days 1. Key factors contributing to muscle twitching in caffeine toxicity include:

• Caffeine's ability to block adenosine receptors, increasing neuronal firing and releasing excitatory neurotransmitters like dopamine and norepinephrine
• The disruption of normal muscle control due to heightened neural activity, causing involuntary contractions or fasciculations
• The increase in calcium release within muscle cells, further promoting muscle irritability Other early-affected muscle groups may include those in the legs and arms, as caffeine's effects are not limited to the facial and hand muscles 1. It is essential to note that reducing caffeine intake and increasing hydration can help alleviate these symptoms, which usually resolve within 24-48 hours as caffeine is metabolized and eliminated from the body. The provided study 1 highlights the importance of considering the effects of caffeine toxicity on the central nervous system and muscle control, particularly in vulnerable populations such as neonates. In real-life clinical practice, it is crucial to prioritize caution and consider the potential for caffeine toxicity when patients present with muscle twitching or other related symptoms, especially if they have a history of high caffeine intake 1.

From the Research

Muscle Groups Affected by Caffeine Toxicity

In cases of caffeine toxicity, various muscle groups can be affected due to the stimulant's impact on the central nervous system and muscle function. The specific muscle groups that twitch first may vary, but based on the available evidence, the following can be inferred:

• Skeletal muscles: Caffeine toxicity can lead to muscle twitching, cramping, and spasms, particularly in the skeletal muscles [ 2 ]. This is often a result of the stimulant's effect on the nervous system, leading to abnormal muscle contractions.
• Respiratory muscles: High levels of caffeine can cause respiratory failure, which may be preceded by twitching or spasms in the respiratory muscles [ 3 ].
• Cardiac muscles: Caffeine toxicity can also affect the heart, leading to arrhythmias, tachycardia, and other cardiac complications [ 4 ]. While not directly related to twitching, these cardiac effects can be life-threatening.

Key Findings

The available evidence suggests that caffeine toxicity can affect various muscle groups, leading to twitching, cramping, and other complications. The specific muscle groups affected may depend on the severity of the toxicity and individual factors. Key findings include:

• Caffeine toxicity can cause muscle twitching, cramping, and spasms [ 2 ].
• High levels of caffeine can lead to respiratory failure and cardiac complications [ 3, 4 ].
• The severity of caffeine toxicity can vary depending on the amount consumed and individual factors [ 5, 6 ].