A 55-year-old patient with a headache explains to the advanced practice registered nurse (APRN) that they have had headaches before, but this one is unusual because of some new symptoms. Which of the following symptoms would prompt an immediate investigation?

A. Headache coming and going over several days is incorrect because intermittent headaches alone are not an immediate red flag unless associated with other concerning symptoms. Many benign headaches, such as tension-type headaches, can be intermittent. B. Fever, night sweats, and recent weight loss is correct because these systemic “red flag” symptoms may indicate a serious underlying condition, such as infection (e.g., meningitis), malignancy, or temporal arteritis. In a patient over 50 with new or unusual headache symptoms, these findings warrant urgent evaluation to rule out secondary causes. C. Losing eyeglasses and using a borrowed pair is incorrect because vision changes due to incorrect glasses prescription are unlikely to indicate an emergent cause of headache. While it can contribute to eye strain, it is not a medical emergency. D. Headache pain similar in nature to prior ones but less severe is incorrect because mild, familiar headaches typically do not require urgent workup, unless associated with new or alarming features (e.g., sudden onset, neurological deficits, or systemic symptoms).