Antibiotics Explained: What They Are and Why Using Them Wisely Matters
6 min read / 2026-06-08
Antibiotics are medicines that kill or stop the growth of bacteria, but using them incorrectly can make them stop working for everyone. This explainer covers how antibiotics work, why resistance is a growing concern, and how to use them safely.
What antibiotics are
Antibiotics are medicines designed to fight infections caused by bacteria — tiny, single-celled living things that can sometimes make us sick. Common bacterial infections include strep throat, urinary tract infections (UTIs), and some ear infections. The word 'antibiotic' comes from Greek words meaning 'against life' — specifically, against bacterial life. Antibiotics work either by killing bacteria directly or by stopping them from multiplying so your immune system can handle the rest. They were first discovered in 1928 when scientist Alexander Fleming noticed that a mould called Penicillium was killing bacteria in his lab. That discovery led to penicillin, the world's first antibiotic, which has saved millions of lives since it came into use in the 1940s.
How antibiotics work
Different antibiotics target different parts of a bacterium. Some attack the outer wall of the bacterium, causing it to fall apart. Others stop the bacterium from making proteins it needs to survive. Still others prevent bacteria from copying their DNA, so they cannot reproduce. Because human cells are built very differently from bacterial cells, antibiotics can target bacteria without harming most of our own cells. However, this only works against bacteria. Antibiotics have no effect on viruses — the germs that cause the common cold, flu, and COVID-19. Taking antibiotics for a viral illness will not help you recover faster and can cause unnecessary side effects like stomach pain or diarrhoea.
A simple example
Imagine your friend gets a bacterial throat infection. The doctor prescribes a 7-day course of antibiotics. By day 3, your friend feels much better and stops taking the tablets. Here is the problem: the weakest bacteria were killed first. The slightly stronger ones are still alive, and without the full course of medicine, they survive and multiply. Those leftover bacteria have now 'learned' to resist that antibiotic. If your friend gets sick again, the same medicine may not work. This is why doctors say: always finish the full course, even if you feel better. Think of it like watering a plant halfway — the job is not really done.
Why antibiotic resistance is a big concern
Antibiotic resistance happens when bacteria change over time so that a medicine can no longer kill them. This occurs naturally to a small degree, but it speeds up when antibiotics are overused or misused — for example, taking them without a prescription, using leftover tablets from a previous illness, or giving antibiotics to farm animals to make them grow faster. The World Health Organization (WHO) calls antibiotic resistance one of the biggest threats to global health. The Centers for Disease Control and Prevention (CDC) in the United States estimates that drug-resistant bacteria cause at least 1.27 million deaths worldwide each year. In India, the problem is serious because antibiotics are widely available without a prescription in many areas, which makes overuse common.
What to remember about safe use
A few simple rules can help protect both you and the people around you. First, only take antibiotics when a doctor prescribes them for a confirmed bacterial infection. Second, always complete the full course your doctor recommends. Third, never share your antibiotics with someone else — their illness may be different. Fourth, do not save leftover antibiotics for later use. Fifth, if you have a cold or the flu, rest and fluids help; antibiotics will not. Following these steps helps make sure that antibiotics keep working for everyone who needs them — including future patients who might face life-threatening infections.
Key words
Antibiotic
A medicine that kills bacteria or stops them from multiplying, used to treat bacterial infections.
Antibiotic resistance
When bacteria change so that an antibiotic can no longer kill them, often due to overuse or misuse of the medicine.
Bacteria
Tiny single-celled living organisms; some types can cause infections in humans and animals.
Immune system
The body's natural defence network that identifies and fights germs like bacteria and viruses.
Key facts
- 1Alexander Fleming discovered penicillin, the world's first antibiotic, in 1928 by accident when he noticed mould killing bacteria in his lab.
- 2Antibiotics only work against bacteria — they have no effect on viruses like those that cause colds or the flu.
- 3The WHO lists antibiotic resistance as one of the top ten global public health threats facing humanity.
- 4The CDC estimates drug-resistant infections cause at least 1.27 million deaths worldwide every year.
- 5In many countries including India, antibiotics are sometimes sold without a prescription, which increases the risk of misuse and resistance.
Why it matters
If antibiotics stop working because of resistance, common infections that are easily treated today could become life-threatening — affecting anyone, anywhere.
Sources
- World Health Organization (WHO) — Antimicrobial Resistance Fact Sheet
- Centers for Disease Control and Prevention (CDC) — Antibiotic Resistance Threats Report
