What is a common side effect associated with theophylline?

Theophylline is a medication often used to treat respiratory conditions such as asthma and chronic obstructive pulmonary disease (COPD) by acting as a bronchodilator. One of the common side effects associated with theophylline is insomnia. This occurs because theophylline is a methylxanthine, which can stimulate the central nervous system, leading to increased alertness and the potential for difficulty falling asleep or staying asleep.

Understanding the mechanism of theophylline helps in recognizing why insomnia is a likely side effect; it enhances the activity of neurotransmitters that promote wakefulness. Additionally, theophylline can also increase heart rate and metabolic rate, which may contribute to restlessness and difficulty in achieving a restful state during sleep.

In contrast, while fatigue, increased appetite, and headaches can be side effects associated with various medications, they are not typically characteristic of theophylline therapy in a direct manner as insomnia is.