Introduction
Few drugs are as revered and feared as antibiotics. They have saved millions of lives, turned once-deadly infections into treatable conditions, and reshaped modern medicine. Yet, paradoxically, they are also among the most overused and misused drugs in the world. Many people still believe that antibiotics can help with almost any illness: a cough, a fever, a sore throat, or even “just in case” when they travel.
The truth is starkly different. Antibiotics fight bacteria, and only bacteria. They do nothing against viruses, and using them inappropriately not only fails to help but also carries significant risks. Misuse contributes to resistance, exposes patients to unnecessary side effects, and interacts dangerously with other medications.
This article explains when antibiotics don’t work, why taking them “just in case” is a bad idea, and how to protect yourself and others through responsible use.
Antibiotics and viral infections
One of the most common myths is that antibiotics are useful for colds and flu. These illnesses are caused by viruses: influenza, rhinoviruses, coronaviruses, adenoviruses. Viruses do not have cell walls for penicillins to block, ribosomes for tetracyclines to shut down, or DNA gyrase for fluoroquinolones to inhibit. They operate with a completely different biology.
Despite this, surveys show that a large proportion of patients expect antibiotics when they visit a doctor with flu-like symptoms. Doctors, under pressure, sometimes oblige. But no matter how strong the antibiotic, it cannot shorten the duration of a cold or prevent viral pneumonia after influenza.
The same mistake happens with acute respiratory viral infections (ARVI). In most cases, runny noses, mild coughs, and fevers in winter are viral. Antibiotics in these situations not only fail to cure but often worsen outcomes by disturbing the gut microbiome or causing side effects. For more detail on possible harms, see
Side effects overview.
There are exceptions: sometimes a viral infection weakens the body enough that bacteria take advantage, leading to “secondary” bacterial pneumonia or sinusitis. But this cannot be predicted at the start of every cold, and routine antibiotics are not the answer. Doctors use clinical signs and sometimes lab tests to decide when bacteria are truly involved.
The illusion of “just in case”
Another dangerous misconception is prophylactic use: taking antibiotics before travel, before a dental visit, or at the first tickle in the throat, “just in case.” The logic feels reassuring: better safe than sorry. The reality is the opposite.
When antibiotics are taken without a clear target, they apply selective pressure to bacteria in the body and environment. The susceptible ones die, but resistant strains survive and multiply. Over time, this makes infections harder to treat, not easier. Resistance does not remain confined to one person: resistant bacteria can spread within households, to classmates, co-workers, or hospital patients. What feels like a small personal safeguard actually contributes to a much larger public health threat.
Unsupervised prophylaxis also creates direct personal risks. Some antibiotics interact with alcohol, contraceptives, or common medications for blood pressure, diabetes, or heart disease. A patient who starts amoxicillin-clavulanate before a long flight “to avoid getting sick” may end up with severe diarrhea in a foreign country, or even an allergic reaction without access to proper care. Another traveler who takes ciprofloxacin preventively might later suffer tendon pain, an uncommon but well-documented complication. The dangers are unpredictable, but they are very real. For more on the interaction risks, see
Drug interactions.
There is also a psychological trap. People who habitually keep antibiotics on hand “for emergencies” may delay seeing a doctor when real bacterial infections develop. They self-medicate for days, sometimes with the wrong drug or the wrong dose, while the infection quietly worsens. By the time they seek professional care, the illness may be advanced or complicated, requiring hospitalization and stronger antibiotics.
Legitimate preventive use exists, but it is tightly defined. A patient with a damaged heart valve might be prescribed a single dose before dental surgery to prevent bacterial endocarditis. A surgical team may administer cefazolin just before an incision to reduce infection risk. These are carefully studied protocols, supported by evidence and tailored to specific risks. They have nothing to do with taking leftover azithromycin before a holiday “just in case.”
The difference is clear: supervised, targeted prophylaxis is medicine; casual, self-prescribed prophylaxis is misuse. The first saves lives, the second wastes one of our most precious resources.
Hidden risks of misuse
Taking antibiotics unnecessarily is not neutral. It carries very real consequences.
The most immediate are side effects. Even common drugs like amoxicillin can cause diarrhea, rashes, or yeast infections. More serious reactions, including anaphylaxis, tendon rupture, liver damage, occur unpredictably. The risk is unjustifiable when there is no bacterial infection to treat.
Another hidden danger is disruption of the microbiome. Our skin, gut, and mucous membranes are populated with beneficial bacteria that play critical roles in digestion, immunity, and protection against pathogens. Unnecessary antibiotics wipe out many of these allies, leaving ecological gaps for resistant or harmful bacteria to colonize.
Finally, resistance remains the greatest long-term risk. Once resistance emerges, it does not stay local. Resistant strains spread across households, hospitals, even continents. Treating infections then requires stronger, more toxic, and more expensive drugs. Every unnecessary antibiotic prescription is a small contribution to a global problem.
Why stewardship matters
The medical community uses the word stewardship to describe the careful, responsible management of antibiotics. It means prescribing them only when needed, at the right dose, for the right duration. Stewardship is not just about preserving drug effectiveness for future generations; it is also about protecting patients here and now from unnecessary harm.
Hospitals and clinics implement stewardship programs to monitor prescribing habits, educate healthcare workers, and provide feedback. But stewardship also begins at the individual level. Patients who resist the urge to demand antibiotics for viral illnesses, or who complete the course exactly as prescribed, are participating in stewardship.
More about this vital framework can be found in
Antibiotic stewardship.
Conclusion
Antibiotics are powerful, but they are not magic bullets for every cough, fever, or sore throat. They do not work against colds, flu, or other viral infections. They are not harmless when taken “just in case.” Misuse exposes patients to unnecessary side effects, dangerous drug interactions, and contributes to the worldwide crisis of resistance.
The rules are simple but critical:
- Take antibiotics only when prescribed by a healthcare professional.
- Do not use them for viral illnesses like colds and flu.
- Avoid self-medication and leftover pills.
- Follow the prescribed dose and duration.
Used wisely, antibiotics remain life-saving tools. Used carelessly, they lose their power – for all of us.