Antibiotics: When They Help, When They Harm
Antibiotics changed medicine. Infections that routinely killed people a century ago are now treated in a few days. That success has made them feel harmless, and they are not. India has one of the highest rates of antibiotic consumption and of antibiotic resistance in the world, and the two are directly connected.
What antibiotics actually treat
Antibiotics kill bacteria or stop them multiplying. They have no effect at all on viruses.
That single fact settles most of the everyday confusion:
- Common cold: viral. Antibiotics do nothing.
- Most sore throats: viral in the large majority of adults. Only streptococcal throat infection benefits.
- Flu and most fevers: viral.
- Acute bronchitis and most coughs: viral, even when the sputum turns yellow or green. Colour reflects immune cells, not bacterial infection.
- Most diarrhoea: viral or self-limiting. Rehydration is the treatment. Antibiotics can prolong carriage in some bacterial causes.
Where antibiotics genuinely matter: pneumonia, urinary tract infection, cellulitis and skin abscess, streptococcal throat, typhoid, tuberculosis, sepsis, meningitis, and infections in people with weakened immunity.
The harms people underestimate
Side effects
Diarrhoea, nausea and rashes are common. More serious are Clostridioides difficile colitis after broad-spectrum use, tendon problems and nerve damage with fluoroquinolones, and allergic reactions that can be severe.
Disruption of the microbiome
A course of broad-spectrum antibiotics reduces gut bacterial diversity for weeks to months. The long-term consequences are still being studied but are not nothing.
Resistance
This is the collective harm. Every unnecessary course applies selection pressure that favours resistant bacteria. In India, resistance to carbapenems, the antibiotics reserved for serious hospital infections, is now common enough that some infections have very few treatment options left. Resistance does not develop in the person; it develops in the bacterial population everyone shares.
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Things that drive misuse here
- Buying antibiotics over the counter without prescription, still widespread despite regulation
- Keeping leftover strips and taking them for the next fever
- Taking a relative’s prescription
- Pressure on doctors for a quick fix, and prescribing to meet expectation
- Antibiotic use in livestock, which contributes to resistant organisms in the food chain
Does the course have to be finished?
The old instruction to always finish the course is being revised. The original rationale, that stopping early breeds resistance, does not hold up well for most community infections; resistance is driven more by total exposure than by stopping early.
Current thinking is more nuanced:
- For some infections, shorter courses are now proven equally effective: three to five days for many uncomplicated pneumonias and urinary infections
- For others, and tuberculosis above all, as well as bone and heart valve infections, completing the full prescribed course is absolutely essential
- The practical rule is to take exactly the course your doctor prescribed and to ask, at the time of prescribing, how many days are needed and why
Do not shorten a course on your own, and equally, do not extend it because you still have tablets left.
Using them sensibly
- Do not ask for antibiotics for a cold, flu or a cough of a few days
- Ask your doctor what the antibiotic is for and how long it is needed
- Take doses at even intervals and complete the prescribed duration
- Never save leftovers for later or share them
- Tell your doctor about previous antibiotic allergies, and be specific about what happened
- Return the strip to a pharmacy take-back scheme where available rather than throwing it in household waste
When you do need to see a doctor
- Fever above 38.5C lasting more than three days, or any fever with rash, stiff neck, confusion or difficulty breathing
- Cough with breathlessness, chest pain or coughing blood
- Burning urination with fever or back pain
- A skin area that is red, hot, swollen and spreading
- Diarrhoea with blood, or dehydration
- Any fever in an infant under three months, which is always urgent
This article is general health information. Antibiotics should only be taken on the advice of a qualified doctor, who can judge whether an infection is bacterial and which drug is appropriate.