What causes a sore throat?

Sore throats (pharyngitis) are most commonly caused by viral infections, though they can also stem from bacteria, allergies, environmental irritants, or acid reflux.¹²³

Viral Infections (Most Common)

Viruses account for the vast majority of sore throat cases (up to 85%–95% in adults and children). They usually clear up on their own within a week:¹²³

• Common cold (rhinovirus, coronavirus)
• Influenza (flu)
• Glandular fever (mononucleosis / Epstein-Barr virus)
• COVID-19
• Chickenpox, measles, and croup (in children)¹²³⁴

Bacterial Infections

Bacterial causes are less common than viral ones, typically requiring a medical evaluation and antibiotics:¹²

• Strep throat (Streptococcus pyogenes / Group A streptococcus), most frequent in children and teens
• Bacterial tonsillitis (inflammation of the tonsils)
• Bacterial sinus infections causing postnasal drip¹²³⁴

Non-Infectious Causes & Irritants

• Allergies: Reactions to pollen, dust mites, pet dander, or mold lead to postnasal drip that irritates the throat lining.¹²
• Environmental irritants: Tobacco smoke, secondhand smoke, dry air (from heating or air conditioning), and chemical fumes.¹²³
• Gastroesophageal Reflux Disease (GERD/GORD): Stomach acid backs up into the esophagus and throat, causing a burning pain or sensation of a lump.¹²³
• Muscle strain: Yelling, singing, or talking loudly and continuously without rest.¹²
• Voice box or upper airway issues: Laryngitis or epiglottitis.¹²
• Other medical conditions: Early HIV infection, fungal infections (oral thrush), or, in rare cases, cancerous tumors of the throat, tongue, or larynx.¹²

For general guidance on symptom relief or when to seek care, you can check resources from the NHS Sore Throat Guide or the CDC Sore Throat Basics.¹²To help narrow down what might be going on:

• How long have you or the person affected had the sore throat?
• Are there other symptoms present (like a high fever, cough, runny nose, or swollen neck glands)?

Most sore throats are caused by viral infections like the common cold or flu, though bacterial infections, allergies, and everyday irritants can also trigger throat pain. Most mild cases clear up on their own within a week.¹²³⁴

Viral Infections

Viruses are the most frequent culprit behind throat inflammation (pharyngitis), accounting for the vast majority of cases. Antibiotics do not treat viral infections.¹²³

• Common cold and flu. Rhinoviruses and influenza viruses cause throat pain alongside symptoms like a runny nose, cough, or body aches.
• COVID-19. Coronavirus infections frequently start with a scratchy or painful throat.
• Glandular fever (mononucleosis). Caused by the Epstein-Barr virus, this illness leads to a persistent sore throat, extreme tiredness, and swollen neck glands.
• Other viral illnesses. Measles, chickenpox, and croup can also irritate the lining of the throat.¹²³⁴

Bacterial Infections

Bacterial throat infections are less common than viral ones, and a doctor may prescribe antibiotics to clear them.¹

• Strep throat. Caused by Group A Streptococcus bacteria, this infection causes sudden, severe pain when swallowing, swollen tonsils with white patches, and a fever without a cough.¹²³
• Tonsillitis. While viruses can trigger tonsillitis, bacteria frequently cause the tonsils at the back of the throat to become red, swollen, and painful.¹²
• Bacterial sinus infections. Mucus draining down the back of the throat from infected sinuses can cause significant soreness.¹

Environmental & Lifestyle Irritants

Non-infectious factors often dry out or inflame the sensitive tissues in your throat.¹²

• Allergies and postnasal drip. Reactions to pollen, dust mites, mould, or pet dander cause mucus to drip down the back of the throat, creating a scratchy feeling.
• Smoke and pollution. Smoking, vaping, secondhand smoke, air pollution, and chemical fumes directly irritate the throat lining.
• Dry air and mouth breathing. Sleeping with your mouth open or spending time in dry indoor heat can leave your throat raw, especially in the morning.
• Vocal strain. Yelling, singing loudly, or talking for long periods without rest strains the muscles in your throat and voice box (laryngitis).¹²³⁴⁵⁶

Other Medical Causes

Less frequently, throat pain stems from internal conditions affecting the digestive tract or airway.¹²

• Acid reflux (GERD). Stomach acid flowing back up into the food pipe (oesophagus) can burn and irritate the throat, often causing hoarseness or a lump-like sensation.¹²
• Rare or serious conditions. Very rarely, a persistent sore throat is linked to severe airway swelling (such as epiglottitis or a throat abscess), early HIV infection, or growths and tumours in the throat.¹²³

When to Seek Medical Advice

You can find full guidance on symptom relief and when to contact a GP on the NHS Sore Throat guide or the Mayo Clinic Sore Throat overview. Seek prompt medical attention if your sore throat lasts longer than a week, comes with a very high fever, or makes it difficult to breathe or swallow fluids.¹²

If you're currently dealing with a sore throat, let me know:

• How long it has lasted
• Any other symptoms you have (like a fever, cough, or runny nose)

I can help you narrow down the likely cause or share safe ways to soothe it at home.

A sore throat is usually caused by inflammation or irritation of the throat, often due to an infection. It can make your throat feel scratchy, painful, dry or uncomfortable when swallowing.

Common causes of a sore throat

1. Viral infections (most common)

• Common cold
• Flu (influenza)
• COVID-19
• Viral tonsillitis
• Glandular fever

2. Bacterial infections

• Strep throat (caused by Group A Streptococcus)
• Bacterial tonsillitis
• Scarlet fever

3. Environmental irritation

• Smoking or vaping
• Dry air or central heating
• Dust or pollution
• Shouting or speaking for long periods

4. Allergies

• Hay fever
• Dust mites
• Pet allergies
• Post-nasal drip (mucus running down the back of your throat)

5. Acid reflux Stomach acid travelling up into your throat can cause:

• A burning sensation
• A persistent sore throat
• A lump-in-the-throat feeling
• Hoarseness, especially in the morning

Common symptoms and what they might indicate

How to soothe a sore throat

• Drink plenty of water.
• Gargle warm salt water.
• Try warm drinks with honey.
• Rest your voice.
• Avoid smoking and vaping.
• Consider paracetamol or ibuprofen if suitable for you.

(Seek urgent medical help) if you have difficulty breathing, cannot swallow, are drooling because you cannot swallow, or develop rapidly worsening symptoms.

A few questions to help narrow down the cause

1. Does your throat hurt when you swallow, or is it sore all the time?
2. Is the pain on one side or both sides?
3. Do you have any other symptoms, such as a cough, blocked nose, fever or swollen glands?
4. How long have you had the sore throat?

I can help you work out what might be causing it based on your symptoms.