Final answer:
One of the main things to watch for when starting antihypertensive medicine is dizziness.
Step-by-step explanation:
One of the main things you should tell the 63-year-old female and her husband to watch for when starting her first antihypertensive medicine is dizziness. Dizziness can be a common side effect of antihypertensive drugs, especially when starting a new medication or when the dosage is adjusted. It is important to monitor for dizziness and report it to the healthcare provider if it persists or worsens.