Final answer:
Ciprofloxacin, a fluoroquinolone antibiotic prescribed for pneumonia, carries a risk of Achilles tendon rupture, among other side effects such as nausea, vomiting, and diarrhea.
Step-by-step explanation:
A patient prescribed Ciprofloxacin, a fluoroquinolone antibiotic, for streptococcal pneumonia is at an increased risk of Achilles tendon rupture. This particular side effect is noted as a serious risk associated with the use of fluoroquinolones. Other common side effects can include gastrointestinal issues such as nausea and vomiting or diarrhea, but tendon rupture, although rarer, is a distinct concern that warrants caution, especially in patients who are older, on corticosteroid therapy, or have kidney, heart, or lung transplants.