What side effect might a patient experience when using bronchodilators?

When using bronchodilators, a patient might experience tremors as a side effect. This occurs because many bronchodilators, particularly beta-2 adrenergic agonists, stimulate the beta receptors not only in the lungs but also in skeletal muscle. This stimulation can lead to increased muscle excitability and contractions, resulting in the tremors that patients may notice, especially in the hands.

The involvement of nervous system stimuli and muscle activity highlights how bronchodilators can unintentionally affect the body beyond their intended respiratory effects. It's also important to consider that these medications are often used in acute situations, like asthma attacks, where the body might already be under stress, further contributing to the likelihood of tremors.

In contrast, other potential side effects like constipation, pneumonia, or weight gain are not commonly associated with bronchodilator use. Thus, the occurrence of tremors is one of the more notable and expected side effects, distinguishing it from the other choices provided.