Which symptom is an indication of theophylline toxicity?

Theophylline is a bronchodilator commonly used in the management of respiratory conditions such as asthma and chronic obstructive pulmonary disease (COPD). However, when therapeutic levels of theophylline are exceeded, it can lead to toxicity, which is characterized by a variety of symptoms. One of the hallmark signs of theophylline toxicity is restlessness. This particularly manifests as an increase in nervousness, anxiety, and an inability to relax.

Restlessness occurs because theophylline impacts the central nervous system, leading to increased arousal and activity. In toxic levels, this stimulation can become excessive, making restlessness a key indicator for healthcare providers to be aware of when monitoring patients on theophylline therapy.

The other symptoms mentioned have different associations. Increased urine output might be a consequence of diuresis, which is not specific to theophylline toxicity. Muscle cramps can occur due to various reasons, including electrolyte imbalances, but are not directly indicative of theophylline toxicity. Coughing is a common symptom in respiratory conditions and does not serve as a specific indicator of toxicity. Hence, restlessness stands out as a distinct and significant symptom of theophylline toxicity.