As we move into the cooler months in Cape Town, it’s very common to start seeing more coughs, sore throats, runny noses and general “flu-like” illnesses. One of the most frequent questions we hear in general practice at this time of year is: “Do I need antibiotics?”

The short answer is that many people don’t.

Understanding the difference between viral infections and bacterial infections helps explain why.

Most Winter Illnesses Are Viral. These include the common cold, influenza (the flu), many sore throats, bronchitis and a large proportion of sinus infections. Viruses infect the body’s cells and use them to replicate, which means antibiotics, which are designed to target bacteria, have no effect on them.

Viral infections typically cause symptoms such as a runny or blocked nose, sore throat, cough, fatigue, headaches, body aches and sometimes a mild fever. While these symptoms can certainly make you feel miserable, viral infections usually improve on their own as the immune system clears the infection. In these cases, treatment focuses on supportive care: rest, hydration, and managing symptoms while the body recovers.

Bacterial infections, on the other hand, are caused by bacteria and require antibiotic treatment. Examples include certain types of pneumonia, urinary tract infections, some throat infections such as strep throat, and specific sinus or skin infections. Occasionally a bacterial infection can develop after a viral illness, but this is far less common than people often assume.

Because symptoms can overlap, it is not always obvious whether an infection is viral or bacterial without a proper clinical assessment. When assessing an infection, doctors consider several factors including the pattern of symptoms, how long the illness has been present, examination findings, and sometimes simple tests. Monitoring how symptoms evolve over time often provides important clues.

It is also helpful to remember that even uncomplicated viral infections can take 7–10 days to fully settle, and a cough after a respiratory virus can sometimes linger a little longer while the airways recover.

This careful approach forms part of what we call antibiotic stewardship, which simply means using antibiotics only when they are truly necessary. In the past, antibiotics were sometimes prescribed “just in case,” but we now know that unnecessary antibiotic use can cause several problems.

Firstly, antibiotics can lead to antibiotic resistance, where bacteria adapt and become harder to treat with the medicines we rely on. This is a growing global health concern and makes serious infections more difficult to manage in the future.

Antibiotics can also have direct downsides for the person taking them. Common side effects include nausea, diarrhoea and stomach upset. They can disrupt the normal balance of bacteria in the gut, which sometimes leads to secondary infections such as thrush or antibiotic-associated diarrhoea. Allergic reactions can occur in some individuals, and although rare, these can occasionally be severe. For these reasons, avoiding unnecessary antibiotics is not only good for public health, but also beneficial for the individual patient.