Final answer:
The correct instruction for a patient taking amitriptyline, a tricyclic antidepressant, is to sit or lie down when feeling lightheaded due to the risk of orthostatic hypotension.
Step-by-step explanation:
The most appropriate instruction for the nurse to include in the patient teaching session for a patient prescribed amitriptyline (Elavil), a tricyclic antidepressant, is "Sit or lie down when feeling lightheaded." Amitriptyline can cause orthostatic hypotension leading to feelings of lightheadedness, and patients need to know how to respond to these symptoms to prevent falls or injury. Consumption of alcohol should be avoided altogether, not just moderated, due to its potential to increase sedative effects and interact negatively with the medication. Foods containing tyrosine do not specifically need to be avoided when taking tricyclic antidepressants. Lastly, taking the medication in the morning is not standard advice since amitriptyline can cause drowsiness and is often prescribed for bedtime use to help with sleep.