What is a critical side effect of furosemide that patients should be educated about?

Furosemide, a loop diuretic commonly used to treat conditions like hypertension and heart failure, has a critical side effect that warrants specific patient education: the risk of hearing loss. This is particularly pertinent because furosemide can cause ototoxicity, which refers to damage to the inner ear and can lead to temporary or permanent hearing impairment. This risk increases when the drug is administered in high doses or infused rapidly, which is why patients need to be aware of any changes in hearing as well as the importance of adhering to prescribed dosages.

In contrast, while the other choices may present symptoms or concerns that could be relevant in different contexts of medication management, they are not as immediate or critical as the risk of hearing loss associated with furosemide. Increased risk of infection and fatigue may relate to other factors or medications but are not specific side effects of furosemide. Weight gain could indicate fluid retention, which is counterintuitive to the expected outcome of furosemide, but it does not represent a critical side effect that would require immediate medical attention or awareness.