Feeling rotten with a cold, so you ask the doctor for antibiotics to knock it out, because antibiotics are the big guns that clear up an infection. A lot of people still expect a script, and feel short-changed without one. Cold equals infection equals antibiotics, surely.
Antibiotics do nothing for a cold, because colds and flu are caused by viruses, and antibiotics only kill bacteria. They cannot touch a virus, so taking them for a cold gives you zero benefit and a real downside: side effects, and the bigger picture of antibiotic resistance, where overuse breeds bacteria that our drugs can no longer kill. Health authorities worldwide now run campaigns specifically to stop people demanding antibiotics for viral illnesses, because resistance is one of the serious slow-moving threats in medicine. The things that actually help a cold are rest, fluids, time, and managing symptoms; a cold typically clears in a week or so on its own. Antibiotics are only warranted if a genuine bacterial complication sets in, like some sinus or chest infections, which a doctor decides. So the script you wanted for your sniffle is useless against it, and quietly making the world's bugs tougher.