Antibiotics vs. antivirals: What’s the difference?
Written by Dr Nelson Lau, MBBS FRACGP, GP & Digital Health Specialist.

Contents

What is an antibiotic?
Antibiotics are powerful medications that fight bacterial infections. They either kill bacteria or prevent them from growing and reproducing, making them a cornerstone of modern medicine. Antibiotics have saved countless lives by effectively treating infections that would otherwise be life-threatening. For example, penicillin—the first widely used antibiotic—revolutionised medicine by effectively treating infections like pneumonia, syphilis, and strep throat. Antibiotics work on specific structures or processes in bacteria—such as the cell wall or protein synthesis—that are not found in human cells. This makes them highly effective against bacteria while having minimal effects on our own tissues. Also read: Antibiotic ResistanceFeeling sick and unsure why? Speak with a GP online in 15 minutes.
Illnesses treated by antibiotics
- Respiratory infections: Bacterial pneumonia, sinusitis, or bronchitis caused by bacteria such as Streptococcus pneumoniae.
- Urinary tract infections (UTIs): Commonly due to Escherichia coli.
- Skin infections: Examples include cellulitis or infected wounds.
- Strep throat: Caused by Streptococcus pyogenes.
What is an antiviral?
- Inhibiting the virus’s ability to attach to or leave the host cell.
- Blocking the virus from replicating its genetic material within the host cell.
- Supporting the immune system’s ability to fight the infection.
- Oseltamivir (Tamiflu) or zanamivir: For influenza.
- Acyclovir or valacyclovir: For herpes infections.
- Antiretroviral therapy (ART): For HIV.
- Sofosbuvir or entecavir: For certain cases of hepatitis B and C.
- Remdesivir: Used for COVID-19 and sometimes other viral infections.
Antiviral illness treatment
Some antiviral treatments can effectively eliminate certain viruses from the body. For instance, specific antiviral regimens for hepatitis C can lead to a complete cure by clearing the virus. However, in many other cases (e.g., the flu, herpes), antivirals primarily reduce symptom duration or severity rather than fully eradicating the virus.Why don't doctors give antibiotics for viral infections?
A major misconception is that antibiotics can treat all infections. However, antibiotics only target bacteria. Viruses have different structures and rely on the host cell’s machinery to reproduce, so antibiotics can’t act on them. Additionally, overusing or incorrectly using antibiotics contributes to antibiotic resistance—bacteria evolve to survive antibiotic treatment, making future infections harder to treat. This is why using the right medication at the right time is crucial. Also read: Taking antibiotics without a prescriptionWhen should you take antivirals?
Antivirals are generally recommended when:- You have (or are suspected to have) a specific viral infection, such as influenza, herpes, or COVID-19.
- Your symptoms are severe or prolonged: Antivirals can reduce the duration of flu symptoms if taken within 48 hours of onset.
- You are at high risk of complications: For example, if you are pregnant, elderly, or immunocompromised, antivirals may be recommended to prevent serious illness.
When should you take antibiotics?
Antibiotics are prescribed when:- You have a confirmed bacterial infection: Lab tests or a clinical exam may indicate a bacterial cause, for example, a high fever with a sore throat confirmed as strep throat.
- You are likely to develop complications: For instance, a UTI that has spread to the kidneys.
- You are recovering from certain surgeries or injuries and are at high risk of bacterial infection.
Secondary infections
Sometimes, a viral infection can weaken the body’s defenses and lead to a secondary bacterial infection (for instance, pneumonia following influenza). In such cases, both antivirals (to manage the underlying virus) and antibiotics (to address the bacterial component) may be appropriate. This should always be guided by a healthcare professional.When to consider antivirals for the flu?
The flu is a common viral illness ranging from mild to severe. Antivirals like oseltamivir (Tamiflu) are most effective when taken within 48 hours of symptom onset. They won’t necessarily cure the flu but can:- Shorten the duration of symptoms by about one to two days.
- Help prevent serious complications, such as pneumonia, especially in high-risk individuals.
How can telehealth help?
Telehealth offers a fast and convenient way to access prescriptions for antiviral and antibiotic medications without visiting a clinic. With a 24/7 online GP consultation, you can:- Discuss symptoms with an AHPRA-registered online doctor or healthcare practitioner through a telehealth appointment.
- Receive a diagnosis and medical advice remotely within 15 minutes.
- Get instant scripts online, COVID treatment or discuss your treatment options
- You can also avail doctor medical certificates, online doctor referrals and so on using telehealth.
Conclusion
Both antibiotics and antivirals are designed to fight infections, but they target vastly different pathogens. Antibiotics are your best bet for bacterial infections, while antivirals address viral infections. Using the wrong medication can lead to resistance or unnecessary treatment, which is why these drugs should only be taken as advised by a healthcare provider. Knowing the difference helps you make informed decisions and protects the effectiveness of these life-saving medications. The next time you’re ill, you’ll have a clearer understanding of whether you need an antibiotic, an antiviral, or simply rest and supportive care.Need a script instantly? Get your prescription sorted within 15 minutes.
What we treat
- Cough
- Nausea & vomiting
- Fever
- Hayfever
- Fatigue
- Sore throat
- Acne
- Hair loss
- Gout
- Eczema
- Rosacea
- Sunburn
- UTI
- Erectile dysfunction
- Contraception
- Morning sickness
- Morning after pill
- Prostate health
- Anxiety
- Depression
- Stress
- Grief & loss
- Antidepressants
- Premature ejaculation
- Asthma
- Blood pressure
- Blood thinners
- Diabetes
- Cholesterol
- Migraines & headaches
- Allergies
- Body ache
- Heartburn & reflux
- Sleep disorder
- Smoking cessation
- Pain relief
- Gastro
Related Articles
Disclaimer
This content is created for informational purposes only. It is not intended to be a substitute for professional medical advice. Always seek the guidance of your doctor or other qualified health professional with any questions you may have regarding your health or a medical condition. For emergencies please immediately contact 000.
Get affordable healthcare on your terms, with quick access to qualified, Australian-registered telehealth doctors & health practitioners, 24/7, 365 days a year. No more searching for ‘doctors near me‘ – Hola connects you instantly.
Address: 79 St Georges Terrace, Perth WA 6000
For urgent medical help & in case of emergency,
call 000.
Hola Health App
Get affordable healthcare on your terms, with quick access to qualified, Australian-registered telehealth doctors & health practitioners, 24/7, 365 days a year. No more searching for ‘doctors near me‘ – Hola connects you instantly.
Address: 79 St Georges Terrace, Perth WA 6000
For urgent medical help & in case of emergency,
call 000.
© Hola Health, a brand of Packapill Pty Ltd