Sore Throat: Causes, Tests & When to See a Doctor

What Causes a Sore Throat?

Most sore throats are caused by viral infections like the common cold or flu and resolve on their own within a week. A smaller number are caused by bacteria, most notably strep throat, which needs antibiotics.

Common Causes

Viral infections (cold, flu, mononucleosis)
Strep throat (bacterial)
Allergies and postnasal drip
Acid reflux (GERD)
Dry air or irritants (smoke, pollution)
Tonsillitis

Strep Throat vs. Viral: Key Differences

Feature	Strep Throat	Viral Sore Throat
Onset	Sudden	Gradual
Fever	Often high	Usually mild
Cough	Usually absent	Common
Swollen tonsils with white patches	Common	Less common
Swollen neck lymph nodes	Common	Variable

Tests Your Doctor May Order

Test	Purpose
Rapid strep test	Detects strep bacteria within minutes
Throat culture	Confirms strep if rapid test is negative but suspicion is high
CBC	Checks for infection, especially if mononucleosis is suspected

See a doctor if: Severe difficulty swallowing or breathing, drooling, a sore throat lasting more than a week, or a high fever above 39.4°C (103°F).

Frequently Asked Questions

When does a sore throat need antibiotics?

Most sore throats are viral and settle without antibiotics. Bacterial (strep) throat, suggested by fever, swollen glands, tonsil pus, and no cough, may need them, guided by a clinical score or throat swab.

When is a sore throat an emergency?

Difficulty breathing or swallowing, drooling, a muffled voice, or severe one-sided pain needs urgent care, as these can signal a serious throat infection or abscess.

How long should a sore throat last?

Most resolve within a week. A sore throat lasting more than 3 weeks, or with a persistent lump or voice change, should be assessed to exclude other causes.

Why most sore throats do not need antibiotics

The large majority of sore throats are viral, and antibiotics neither shorten them nor prevent complications. The clinical difficulty is that a viral throat and a streptococcal one can look similar, which is why scoring systems exist. The Centor criteria, and the modified FeverPAIN score used widely in the UK, combine features such as fever, absence of cough, tender neck glands and pus on the tonsils to estimate the chance of a bacterial cause and guide whether to test or treat.

Even with a confirmed strep throat, the benefit of antibiotics is modest for symptoms, shortening illness by around a day. The stronger argument for treating is reducing onward spread and, historically, preventing rheumatic fever, which remains a meaningful concern in some populations and is rare in others.

Sore throats that are not infections

Acid reflux often presents as a persistent morning sore throat with hoarseness and throat clearing, without fever.
Post-nasal drip from allergy or sinus disease irritates the throat continuously and improves when the underlying cause is treated.
Dry air, mouth breathing and voice overuse, common in singers, teachers and anyone recovering from a blocked nose.
Smoking and vaping, and occupational exposure to dust or fumes.
Medication effects: inhaled steroids can cause thrush, and some drugs reduce saliva and leave the throat persistently raw.

When a sore throat is an emergency

A few presentations need immediate assessment rather than a swab. Difficulty breathing, drooling because swallowing is impossible, a muffled or hot-potato voice, severe one-sided pain with trismus, or a swollen neck with high fever can indicate abscess or airway compromise. So can a sore throat with a widespread rash, or one in someone taking carbimazole, methotrexate, clozapine or chemotherapy, where a very low white cell count is possible and needs same-day blood testing.

What helps while it settles

Regular paracetamol or ibuprofen, taken at proper doses rather than sporadically, does more for pain than most throat preparations. Anaesthetic lozenges and sprays give short-lived relief. Warm or cold fluids, whichever suits, keep the throat comfortable and maintain hydration. Honey has reasonable evidence for cough and throat discomfort in adults and children over one year, but must not be given to infants under twelve months.

Sore Throat: Causes, Tests & When to Worry