Which of the following conditions requires immediate medical attention when taking ciprofloxacin?

The condition that requires immediate medical attention when taking ciprofloxacin is yellowing of the eyes. This symptom may indicate the development of liver problems, specifically a condition known as jaundice, which can arise from drug-induced liver injury. Ciprofloxacin, being part of the fluoroquinolone class of antibiotics, has been associated with various adverse effects, and liver toxicity is one of the more serious potential reactions.

It is important for patients taking ciprofloxacin to be vigilant for any signs of liver dysfunction, as early detection can be crucial for preventing more severe complications. Other symptoms that could accompany liver issues include dark urine, pale stools, and abdominal pain, but yellowing of the eyes is a prominent and easily noticeable sign that indicates a need for urgent assessment.

The other conditions listed, such as increased appetite, skin dryness, and muscle soreness, while they may be uncomfortable or concerning to patients, do not typically indicate a medical emergency related to ciprofloxacin treatment. Therefore, yellowing of the eyes stands out as the symptom that signals a serious potential complication requiring prompt evaluation.