Final answer:
Clonidine, a medication used for various conditions, can cause bradycardia as an adverse effect. Bradycardia is a slower than normal heart rate.
Step-by-step explanation:
Clonidine is a medication used for various conditions such as hypertension, anxiety, pain, and attention deficit hyperactivity disorder (ADHD). The nurse should inform the client that a potential adverse effect of this medication is bradycardia, which is a slower than normal heart rate. This is because clonidine acts as an alpha-2 adrenergic agonist and can decrease sympathetic nervous system activity, leading to a decreased heart rate.