Final answer:
The nurse should teach the older adult client about the possible adverse effect of dizziness when standing due to blood pressure medicine.
Step-by-step explanation:
The nurse should teach the older adult client that a possible adverse effect of the blood pressure medicine is dizziness when standing (option b). This is known as orthostatic hypotension, which occurs when blood pressure drops upon standing quickly. It is important for the client to be aware of this side effect to prevent falls and injuries.
Options a and c are incorrect. Taking the medicine on an empty stomach is not necessary, as blood pressure medicine can be taken with or without food. It is also incorrect to claim that there are no adverse effects from blood pressure medicine. Lastly, option d is not the most important aspect to teach the client about, although a severe drop in blood pressure can occur in some cases.