Quick answer
Antibiotics only work against bacteria: they do nothing for the flu, a cold, or other viral infections. In Mexico, roughly 3 out of 4 families took them in recent months, most without seeing a doctor. Using them without medical guidance makes bacteria resistant, so the treatment stops working when you genuinely need it. At AVA Médica we examine you and run lab work the same day to determine whether antibiotics are actually necessary.
Most of us have been there: a cold starts, there's no time to see a doctor, and someone you trust suggests taking the antibiotic left over from last time. It isn't ignorance — it's practicality. It's fast, it's cheap, and it often feels like you already know what you have. The problem is that with antibiotics, that decision carries consequences worth knowing about.
Why does this matter so much?
A community study in Mexico found that about 75% of families had used antibiotics in the previous six months, most without a medical consultation. Northern Mexico has some of the highest self-medication rates in the country. Globally, the World Health Organization reports that antibiotic resistance rose more than 40% between 2018 and 2023, and Mexico's National Institute of Public Health estimates tens of thousands of deaths a year tied to infections that no longer respond to treatment.
This isn't about scaring anyone. It's about keeping a life-saving resource working for the moment you or your family really need it.
The 5 most common myths
These are the ones we hear most often in the clinic, and what the evidence says about each:
| Myth | What actually happens |
|---|---|
| "Antibiotics cure the flu" | The flu and the common cold are caused by viruses. Antibiotics only act on bacteria: they won't shorten the flu or prevent complications. |
| "I feel better, so I'll stop taking it" | Feeling better doesn't mean the infection is gone. Cutting treatment short leaves the most resistant bacteria alive. |
| "I have one left over, I'll take that" | Every infection and every bacterium responds to a different antibiotic. What worked before may not work now, and leftover doses are almost never a full course. |
| "It worked for my neighbor, so it'll work for me" | The right antibiotic depends on the type of infection and, in many cases, on lab work. It isn't prescribed by word of mouth. |
| "Green mucus means it's bacterial" | Mucus color does not distinguish a viral infection from a bacterial one. It's one of the most widespread beliefs and one of the least accurate. |
What exactly is resistance?
Every time an antibiotic is used unnecessarily or incompletely, the weakest bacteria die and the strongest survive and multiply. Over time those resistant bacteria become dominant, and infections that once cleared in a week start requiring longer, costlier, or intravenous treatment. It's a problem built gradually, at home, through decisions that seem harmless.
When are antibiotics actually needed?
There are situations where treatment is necessary and shouldn't be delayed. These are some of the signs a doctor evaluates:
- High fever lasting more than three or four days.
- Severe ear pain along with fever.
- Visible pus in the throat or in a wound.
- Cough with phlegm and high fever that isn't improving.
- Symptoms that get worse after you had started to improve.
- A lab culture confirming the bacteria.
None of these can be assessed on your own: they all require a medical exam, and several need a test to confirm. That's exactly the difference between treating an infection and guessing at it.
The most practical thing you can do
Before taking something that's been sitting in a drawer, a consultation is worth more. At AVA Médica we see walk-ins seven days a week and have a lab on site, so a single visit can cover the exam, the test if it's needed, and clear guidance: sometimes that means an antibiotic, and many other times the answer is that you don't need one.
This information is general and does not replace a medical consultation. Always consult your doctor for a personalized diagnosis and treatment.