Sore throat, pharyngitis and tonsillitis: when antibiotics actually help

What a sore throat usually is

A sore throat — pharyngitis when the back of the throat is inflamed, tonsillitis when the tonsils themselves are inflamed and sometimes coated with pus — is one of the most common reasons Australians visit a GP. The reassuring headline: in low-risk adults and children, the great majority of sore throats are caused by viruses and resolve within three to seven days with simple supportive care.

That single fact reframes the whole conversation. The clinical question for a GP is not usually “is this serious?” — the great majority are not. It is “is this one of the smaller number that needs antibiotics, or that hides a complication?” The answer depends on the cause, the severity, the risk profile of the person in front of them, and a small number of specific red flags.

This article walks through how to think about that question — drawing on Therapeutic Guidelines, RACGP guidance, NPS MedicineWise, the Royal Children’s Hospital Melbourne clinical practice guidelines, and the RHDAustralia 2020 guideline for higher-risk populations.

What causes a sore throat

Viruses (most cases)

Common viral causes include rhinovirus (the usual common-cold virus), adenovirus, influenza, COVID-19, parainfluenza, enteroviruses, and Epstein-Barr virus. Viral sore throats typically come with one or more accompaniments: runny nose, cough, hoarseness, red or watery eyes, generalised muscle aches, or mild fever. They generally improve steadily over three to seven days.

A particular viral cause worth knowing about is infectious mononucleosis (glandular fever) from Epstein-Barr virus. It tends to affect teenagers and young adults, and presents with severe sore throat, prolonged fatigue, swollen lymph nodes in the back of the neck or more widely, and sometimes an enlarged spleen and liver. A blood test (FBC and monospot or EBV serology) confirms it. Glandular fever is managed with supportive care; antibiotics do not help, and amoxicillin in particular can cause a widespread rash in people with active EBV. Contact sport is avoided for four to six weeks because of the small risk of splenic rupture.

Group A streptococcus (strep throat)

Group A streptococcus is the bacterial cause that matters most. It accounts for roughly 10 to 15 per cent of adult sore throats and around 30 per cent of paediatric sore throats. Classic features are an abrupt onset of throat pain, fever, tender lymph nodes in the front of the neck, white patches or pus on the tonsils, and the absence of cough or runny nose. Strep can also produce scarlet fever — a sandpaper-textured rash, a strawberry-coloured tongue, and pale skin around the mouth.

Untreated strep matters for two reasons. First, in a small subset of people, it can lead to acute rheumatic fever two to four weeks later — an immune response that can damage heart valves. Second, it can occasionally lead to post-streptococcal glomerulonephritis (a kidney complication) one to three weeks later, or, very rarely, to deep neck-space infections.

Other causes

Less common but clinically important causes include gonococcal pharyngitis (often without symptoms; relevant to sexual-health history), HIV seroconversion illness, herpes simplex virus, hand-foot-and-mouth disease in children, candida (thrush, in people on inhaled steroids or who are immunocompromised), and — in adults over 50 with persistent one-sided symptoms — oropharyngeal cancer, particularly HPV-related tonsillar cancer.

How a GP works out what is going on

Clinical scoring tools

Two scoring tools are used in Australian general practice to estimate the likelihood of strep throat and guide whether a swab or antibiotics are warranted:

• Centor (modified McIsaac) score — one point each for: fever above 38 °C, no cough, tender front-of-neck lymph nodes, tonsillar pus, age under 15 (minus one if 45 or older). A score of 3 or more prompts a swab; a score of 4 or more may prompt empirical treatment in some settings.
• FeverPAIN score — one point each for: fever in the last 24 hours, pus on the tonsils, rapid attendance (within three days), inflamed tonsils, no cough or runny nose. A score of 4 or more prompts swab or treatment consideration.

Both tools are imperfect — they neither rule strep in nor rule it out with complete confidence — but they significantly reduce unnecessary antibiotic prescribing while catching most cases that would benefit.

Throat swab and rapid antigen test

A throat swab is a quick, painless sample from the back of the throat and tonsils, sent to a pathology lab for culture and sensitivity. Results take 24 to 48 hours. Some clinics now also have a rapid antigen test (RAT) for strep that gives an answer in about ten minutes, which can support same-visit decisions about antibiotics. A swab is most useful when the clinical score is moderate and the decision about antibiotics is genuinely uncertain.

Blood tests

A full blood count and EBV serology may be added if glandular fever is suspected — particularly for adolescents and young adults with prolonged fatigue, severe sore throat, and swollen lymph glands. HIV and sexual-health screening is considered when the sexual-history context suggests risk. ASO (antistreptolysin O) titres are used in working up suspected rheumatic fever, not for diagnosing acute sore throat.

Treatment: what helps and what does not

Symptomatic care (for almost everyone)

For most sore throats, the most effective things are also the simplest:

• Paracetamol and ibuprofen at standard doses are the most effective pain and fever relief for most people. Ibuprofen is avoided in dehydration, significant kidney impairment, or in children under three months. Refer to HealthDirect or your pharmacist for dosing.
• Warm salt-water gargles — half a teaspoon of salt in a glass of warm water — provide modest but real relief.
• Throat lozenges containing local anaesthetics ease pain transiently.
• Honey and lemon drinks help (avoid honey in children under one year because of the risk of infant botulism).
• Hydration and soft cool foods — ice blocks, yoghurt, smoothies — help when swallowing is painful.
• Rest and staying off school or work while febrile, both to recover and to reduce spreading the infection.

Antibiotic stewardship — when antibiotics are warranted

For low-risk Australian adults and children, NPS MedicineWise and eTG recommend symptomatic treatment first. Antibiotics are considered when:

• Strep is confirmed on swab in someone with significant symptoms
• The clinical picture strongly suggests strep (e.g. scarlet fever)
• There is a complication such as quinsy
• The person is immunocompromised
• The person is at higher risk of rheumatic fever (see next section)

When antibiotics are warranted for strep, penicillin (phenoxymethylpenicillin) for ten days is the standard first-line treatment. People with non-severe penicillin allergy are usually given a cephalosporin; those with severe penicillin allergy receive a macrolide such as azithromycin. Your GP and pharmacist will work through the specific regimen for you — including doses, alternatives if you have allergies, and what to do if symptoms worsen.

Why antibiotic stewardship matters

Unnecessary antibiotics are not free of cost. They cause rash, gut upset and thrush in a meaningful minority. They contribute to antibiotic resistance — a population-level harm Australia takes seriously. And in suspected glandular fever, amoxicillin can produce a widespread rash. The clinical evidence in adults and children at low risk of rheumatic fever shows the benefit of antibiotics over symptomatic care is small in terms of symptom duration (around 16 hours less of symptoms).

Higher-risk populations: rheumatic fever prevention

In some Australian populations, the calculus around antibiotics is genuinely different. Aboriginal and Torres Strait Islander Australians living in remote and northern communities, Maori and Pacific Islander Australians, and people with a previous episode of acute rheumatic fever carry a much higher risk of rheumatic heart disease following strep throat or strep skin infection.

The RHDAustralia 2020 guideline recommends a different approach in these populations: prompt empirical penicillin for any sore throat or skin sore, without waiting for swab results. This may be oral penicillin for ten days, or a single intramuscular injection of benzathine penicillin G if adherence to a ten-day course is uncertain. Household contacts with skin sores or sore throat during outbreaks are also treated.

People who have had a previous episode of acute rheumatic fever are enrolled on a state rheumatic heart disease register and receive monthly penicillin injections as secondary prevention to at least age 21, and longer if there is established rheumatic heart disease. This program is delivered through GPs, Aboriginal Community Controlled Health Services, and specialist services and is one of the highest-impact preventive programs in Australian medicine.

When to see a GP — and when to head straight to ED

See a GP within a day or two

• Sore throat lasting beyond a week without improvement
• Significant fever, severe pain on swallowing, or rapidly worsening symptoms
• Suspected glandular fever (prolonged fatigue, severe sore throat, swollen glands)
• Persistent one-sided throat or ear pain in an adult, particularly over 50
• Sexual-health concerns and pharyngitis together
• A child who is unusually unwell, drinking poorly, or whose parents are worried

Go straight to ED (red flags)

• Drooling — saliva running out because swallowing is too painful
• Stridor — high-pitched noisy breathing in or out
• Severe difficulty breathing, sitting forward to breathe (tripoding)
• Trismus — inability to fully open the mouth
• Muffled hot-potato voice
• Severe one-sided throat pain, particularly with deviation of the uvula or a bulge in the throat — this can indicate quinsy (peritonsillar abscess), which needs urgent drainage and intravenous antibiotics
• Neck stiffness or a swollen, painful neck
• Confusion, lethargy, or signs of sepsis — high fever, fast heart rate, low blood pressure, mottled skin
• A child under five with neck stiffness, fever and drooling — possible retropharyngeal abscess

These are uncommon but serious — and they tip the situation from a general-practice issue to an emergency one.

What this article is and is not

This is general health information drawn from current Australian guidelines — Therapeutic Guidelines, RACGP, the RHDAustralia 2020 guideline, NPS MedicineWise, the Royal Children’s Hospital Melbourne clinical practice guidelines and the Australian Medicines Handbook — plus international references where they are useful. It is not personal medical advice and does not replace seeing your own GP. Specific decisions about whether a swab is needed, whether antibiotics are warranted, and which medication and dose are appropriate are made by your treating clinician, taking your full history and risk profile into account.

For Australian consumer-friendly information: HealthDirect — Sore throat · Better Health Channel — Sore throat.

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Sources cited

1. Therapeutic Guidelines (eTG complete) — Antibiotic: Pharyngitis
2. RACGP — Sore throat in general practice
3. RHDAustralia 2020 — Australian Guideline for ARF and RHD
4. NHMRC — ARF/RHD guideline endorsement
5. NPS MedicineWise — Antibiotics for sore throat
6. Australian Medicines Handbook
7. Royal Children’s Hospital Melbourne — Sore throat clinical practice guideline
8. HealthDirect — Sore throat
9. Better Health Channel — Sore throat
10. NICE NG84 — Sore throat (acute) antimicrobial prescribing