Final answer:
The nurse should be aware that phenylephrine, an over-the-counter medication for colds and allergies, can cause severe hypertension when taken with tranylcypromine, a MAOI prescribed for major depressive disorder.
Step-by-step explanation:
When a client with major depressive disorder is newly prescribed tranylcypromine, a monoamine oxidase inhibitor (MAOI), the nurse should be alert to potential adverse reactions with certain over-the-counter medications. Phenylephrine, an adrenergic agent found in many cold, sinus, and allergy medications, can cause a dangerous interaction when taken with MAOIs like tranylcypromine, leading to severe hypertension. Other medications, such as lansoprazole, naproxen, and magnesium hydroxide, do not interact adversely with tranylcypromine.