Sore Throat

Causes, symptoms, how to tell viral from bacterial, self-care and when a sore throat needs medical assessment.

What is a sore throat?

A sore throat is pain, scratchiness or irritation of the throat, usually worse when you swallow. The medical term for inflammation of the throat is pharyngitis, referring to the pharynx — the tube running from behind the nose down to the top of the oesophagus and windpipe.

It is a symptom rather than a diagnosis in itself. Something has irritated or infected the lining of the throat, and the pain is your body's inflammatory response to that. Identifying what caused it determines whether treatment is needed and what kind.

The throat is unusually exposed. Everything you breathe and everything you swallow passes through it, so it encounters more airborne viruses, bacteria, allergens and irritants than almost any other tissue in the body. That exposure explains why sore throats are so common, and why most of them are simply the throat doing its job as a first line of defence.

Types of sore throat

Several distinct conditions all present as a sore throat. The terms overlap and are often used loosely, so it is worth separating them.

What causes a sore throat

Viral infections

The most common cause by a wide margin. Rhinoviruses (the common cold), influenza, adenovirus, coronaviruses including the one causing COVID-19, parainfluenza, enteroviruses and the Epstein-Barr virus all commonly produce a sore throat.

These viruses infect the whole upper respiratory tract rather than the throat alone, which is why a viral sore throat almost always arrives with company: a blocked or runny nose, sneezing, a cough, hoarseness or watery eyes.

Bacterial infections

Group A Streptococcus accounts for most bacterial sore throats. It causes roughly 5 to 15 per cent of sore throats in adults and 20 to 30 per cent in children aged 5 to 15.

Unlike respiratory viruses, group A strep colonises the throat and tonsils specifically. That narrower target produces the characteristic pattern: intense localised throat pain and swollen, pus-flecked tonsils, typically without the runny nose and cough of a cold.

Non-infectious causes

A sore throat does not have to mean an infection at all, and these causes are frequently overlooked when a sore throat persists.

Symptoms

The core symptom is throat pain that worsens on swallowing. What accompanies it varies with the cause.

• Pain or scratchiness in the throat, worse when swallowing or talking
• Red, swollen tonsils, sometimes with white or yellow patches of pus
• Tender, swollen glands in the neck, particularly under the jaw
• Fever, often 38C or above with bacterial infection
• Hoarse or muffled voice
• Earache, referred pain because the throat and ear share nerve supply
• Bad breath
• Headache and tiredness
• Loss of appetite, often because swallowing hurts too much
• Cough, runny nose and sneezing where the cause is viral
• Tummy pain, nausea or vomiting, mainly in children with strep

Symptoms usually peak within the first two to three days and then improve steadily.

Viral or bacterial: how to tell

This is the question that determines everything about treatment, and the most common misconception is that severity indicates cause. It does not. A viral sore throat can be excruciating and a bacterial one can be mild.

What discriminates is the pattern of accompanying symptoms.

How a sore throat is assessed in the UK

UK practice relies on clinical scoring rather than routine throat swabbing. NICE recommends the FeverPAIN score, with the older Centor criteria as an accepted alternative.

FeverPAIN

Five criteria, one point each:

• Fever in the last 24 hours
• Purulence — pus visible on the tonsils
• Attend rapidly — sought help within three days of onset
• Inflamed tonsils — severely, not just mildly, inflamed
• No cough or coryza

Centor criteria

Four criteria, one point each: tonsillar exudate; tender anterior neck glands; history of fever above 38C; absence of cough. A score of 0 to 2 makes strep unlikely. A score of 3 or 4 raises the probability to roughly 32 to 56 per cent.

Testing

Rapid antigen tests can detect group A strep from a throat swab in minutes and are sold in some UK pharmacies. A positive result is reasonably reliable; a negative result less so, since these tests can miss genuine infections. Throat culture is more accurate but takes two to three days, by which point most sore throats are already resolving. Neither is used routinely in NHS primary care, because scoring plus clinical judgement is usually sufficient.

Do you need antibiotics?

Usually not. Two facts drive that conclusion.

First, most sore throats are viral, and antibiotics have no effect whatsoever on viruses. Second, even bacterial sore throats are largely self-limiting in otherwise healthy people, and antibiotics shorten symptoms by only about 16 hours on average.

Antibiotics are therefore prescribed not primarily to make you feel better faster, but to reduce the small risk of complications and to shorten how long you remain infectious to others.

When antibiotics are appropriate

• A FeverPAIN score of 4 or 5, or a Centor score of 3 or 4
• You are systemically unwell rather than simply uncomfortable
• Signs suggesting quinsy or another spreading infection, which need urgent assessment
• A weakened immune system, poorly controlled diabetes, chemotherapy or long-term steroids
• Scarlet fever, indicated by a fine sandpaper rash
• Symptoms worsening rather than settling after three to five days

Which antibiotic

Phenoxymethylpenicillin (penicillin V) is first choice in UK guidance, at 500mg four times daily or 1000mg twice daily for 5 to 10 days in adults. Clarithromycin is the alternative for penicillin allergy, and erythromycin is preferred in pregnancy. Amoxicillin is deliberately avoided because it causes a widespread rash if the underlying cause turns out to be glandular fever.

Self-care and symptom relief

For the majority of sore throats, this is the treatment — and it is genuinely effective, provided it is done properly rather than half-heartedly.

Honey, medicated lozenges, cool foods and ice lollies all provide additional comfort. Vitamin C does not shorten an established sore throat, and the evidence for zinc lozenges is weak and inconsistent.

Sore throat in children

Sore throats are more common in children, peaking between ages 5 and 15, and strep accounts for a larger share of cases than in adults.

• Different symptom mix — tummy pain, nausea and vomiting are common and can dominate over the throat complaint
• Dehydration is the main practical risk — watch fluid intake, wet nappies and urine output rather than focusing on the throat
• Higher chance of bacterial cause — 20 to 30 per cent versus 5 to 15 per cent in adults
• Scarlet fever is more likely — watch for a fine sandpaper rash, flushed cheeks and strawberry tongue
• Uncommon under three — strep throat is rare in this age group, where viral causes dominate
• Enlarged tonsils are normal — large tonsils between infections are not a problem unless they disturb sleep or breathing

Sore throat in pregnancy

Sore throats in pregnancy follow the same pattern as outside it — mostly viral, mostly self-limiting — but the treatment options differ.

Paracetamol is the pain reliever of choice. Ibuprofen and other anti-inflammatories are generally avoided in pregnancy, particularly after 20 weeks. Do not assume a pharmacy throat spray or lozenge is automatically suitable; check the specific pack and ask a pharmacist.

Where a bacterial infection genuinely needs treating, phenoxymethylpenicillin is generally considered suitable in pregnancy, with erythromycin preferred if there is a penicillin allergy. Any medicine in pregnancy should be prescribed by a clinician who knows your history — usually your midwife or GP.

Complications

Complications are uncommon in the UK and far rarer than before antibiotics existed. They are nonetheless the reason treatment remains available for the minority who need it.

• Quinsy (peritonsillar abscess) — a pus collection beside a tonsil, occurring in roughly 1 in 50 cases of acute tonsillitis. Severe one-sided pain, difficulty opening the mouth and a muffled voice. Needs same-day hospital assessment.
• Otitis media — middle ear infection spreading from the throat, mainly in children
• Sinusitis — spread of infection into the sinuses
• Scarlet fever — toxin-mediated rash with streptococcal infection. A notifiable disease in the UK.
• Acute rheumatic fever — an immune reaction two to four weeks after infection affecting the heart, joints and nervous system. Now rare in the UK but a major cause of heart disease globally.
• Post-streptococcal glomerulonephritis — kidney inflammation following strep infection
• Invasive group A strep — very rare but serious, causing sepsis or deep tissue infection

Persistent and recurrent sore throat

A sore throat that will not settle behaves differently from one that keeps coming back, and the two need distinguishing.

Persistent sore throat lasting beyond a week is most often a slow-clearing virus, glandular fever, or an ongoing irritant such as reflux, smoking or allergies. Antibiotics are rarely the answer, because duration alone is not evidence of bacterial infection.

Recurrent episodes with well periods in between suggest repeated infections or chronic tonsillitis. UK criteria for considering tonsillectomy referral are seven or more disabling episodes in one year, five or more per year for two years, or three or more per year for three years. Keeping a simple diary of dates and severity is what a GP needs to judge whether those criteria are met.

When to seek help

Contact NHS 111 or your GP the same day if:

• You have a very high temperature, or feel hot and shivery, and cannot bring it down
• Symptoms are getting worse after three to five days rather than better
• A fine red sandpaper rash develops alongside the sore throat
• You have a weakened immune system, are having chemotherapy, or take medicines that suppress immunity
• You cannot keep fluids down

Arrange a routine appointment if your sore throat has lasted more than a week without improving, keeps returning, or is not responding to regular pain relief.

Prevention

You cannot prevent every sore throat, but you can reduce how often you get one and how badly it affects you.

• Wash hands regularly, particularly during winter and after contact with someone unwell
• Avoid sharing cups, cutlery, water bottles, towels and toothbrushes
• Stop smoking and vaping — the single biggest modifiable factor for recurrent throat irritation
• Treat reflux if you have symptoms of it, since untreated reflux causes chronic throat inflammation
• Manage allergies to reduce post-nasal drip
• Humidify dry rooms, particularly bedrooms in winter
• Stay up to date with flu vaccination if eligible
• Stay home while infectious — 24 hours after starting antibiotics, or until you feel well if not taking them