What is a common side effect of theophylline?

Theophylline is a medication commonly used as a bronchodilator in the treatment of respiratory diseases such as asthma and chronic obstructive pulmonary disease (COPD). One of the more commonly reported side effects of theophylline is insomnia. This occurs because theophylline acts as a stimulant, which can increase alertness and make it difficult for some patients to relax and fall asleep. As a result, those taking theophylline may experience difficulties with their sleep patterns, leading to insomnia.

In the context of the other side effects, while arrhythmias, seizures, and severe headache are notable concerns associated with theophylline, they are generally considered less common than insomnia. Theophylline can lead to increased heart rate and potential arrhythmias, particularly at higher serum concentrations, but the more prevalent complaint is difficulty sleeping. Severe headaches can occur as well, often associated with higher doses or toxicity, but they are not as universally reported as insomnia. Thus, it is crucial to monitor patients for sleep disturbances when prescribing this medication.