How do I know if I need antibiotics when I’m sick?

URTIs are one of the most common reasons people visit their GP in Australia.¹ Often, there’s an expectation of walking away with a prescription for antibiotics. But here’s the problem – most URTIs are caused by viruses, meaning antibiotics are completely ineffective. Taking them unnecessarily can lead to side effects², added costs (who wants to pay for a prescription they don’t need), and most concerningly, growing antibiotic resistance³.

So, what actually helps? In this blog, we break down what URTIs are, how to manage them, and when antibiotics might genuinely be needed.

What are the symptoms of a URTI?

URTIs affect your nose, sinuses, and throat. You might experience:⁴

• A blocked or runny nose
• Cough
• Sore throat
• Sneezing
• Headache
• Feeling generally unwell
• Fever (though this is rare)

Most of the time, these symptoms clear up on their own within two weeks.⁴

What causes URTIs?

About 90% of URTIs are caused by viruses.⁵ In other words, 9 out of 10 cases won’t respond to antibiotics. Common viruses include:

• Rhinoviruses: The most common cause of the common cold, responsible for more than 50% of cases⁶
• Coronaviruses: Including those that cause common colds as well as more severe diseases like COVID-19
• Influenza viruses: Can cause more severe symptoms than the common cold
• RSV (Respiratory Syncytial Virus): Especially common in young children, RSV is a leading cause of bronchiolitis and upper respiratory symptoms
• Parainfluenza viruses: Often linked to croup in kids
• Adenoviruses: Can cause sore throat, fever, and conjunctivitis

Only around 10% of URTIs are caused by bacteria, such as:

• Streptococcus pyogenes: The bacteria behind strep throat
• Haemophilus influenzae: Can cause sinus or ear infections
• Streptococcus pneumoniae: Can contribute to more severe bacterial infections, such as pneumonia, but can also cause sinusitis and middle ear infections
• Moraxella catarrhalis: Often found in cases of middle ear or sinus infections

While it may still be a commonly held belief, green or yellow mucus isn’t a reliable sign of a bacterial infection.⁷ In other words – don’t play doctor based on what’s in your tissue.

How are URTIs treated?

For viral infections, the best treatment is supportive care:

• Rest and stay hydrated
• Use paracetamol or ibuprofen for pain or fever
• Try lozenges or throat sprays
• Use decongestants or saline nasal sprays

Cough medicines are available, but they don’t usually offer much relief.⁸

If your doctor suspects a bacterial infection (like strep throat), antibiotics may be prescribed – but only when clearly needed. One of the ways your doctor can differentiate between a bacterial and viral infection is with a swab from your nose or throat.⁹

When should you see a doctor?

While most URTIs get better on their own, there are some red flags to watch for. These include:

• Fever over 39°C that doesn’t improve
• Severe pain, such as in the sinus or throat that is not relieved by painkillers
• Difficulty breathing or shortness of breath, especially if you have an underlying respiratory condition
• Coughing up blood
• Symptoms lasting more than 10 days without improvement, especially if you experience a worsening cough
• Severe sore throat with difficulty swallowing and bright red tonsils, particularly with white spots, which can be symptoms of strep throat

If you experience any of the above, it’s important to seek medical attention to rule out more serious infections or complications, like pneumonia or bacterial sinusitis.

Why avoiding unnecessary antibiotics matters

Prescribing antibiotics for viral infections is a classic example of low-value care, defined as care that provides little benefit, is unnecessary, or in some cases, actually causes harm. Some studies suggest antibiotics are prescribed up to nine times more often than guidelines recommend for URTIs in Australia.¹⁰

Not only are antibiotics ineffective against viruses, but overusing them contributes to a much bigger problem: antibiotic resistance.

What is antibiotic resistance?

Antibiotic resistance happens when bacteria evolve to resist the effects of medications that once killed them. This makes common infections harder, and sometimes impossible, to treat. According to the World Health Organization, antimicrobial resistance (AMR) was directly responsible for 1.27 million deaths globally in 2019 and contributed to nearly 5 million deaths overall.¹¹

As resistance grows, we risk losing the ability to treat everyday infections. It also puts other medical procedures, like surgeries, cancer treatments, and even childbirth, at greater risk, because they rely on effective antibiotics to prevent and treat infection.¹¹

Every time antibiotics are used when they’re not needed, we increase the risk that they won’t work when they truly are. That’s why it’s so important to use them wisely, and only when your doctor confirms they’re necessary.

The bottom line

If you’ve got a cold, sore throat, or other URTI symptoms, there’s a 9 out of 10 chance you don’t need antibiotics. Instead of asking for a prescription that will likely do you more harm than good, focus on rest, hydration, and symptom relief.