Most sore throats are caused by viruses, such as the ones behind colds and flu, and they usually get better by themselves within a week. Irritation from smoke or dry air, allergies with post-nasal drip and acid reflux explain many of the rest. Strep throat, a bacterial infection, is the main cause that needs a test and sometimes antibiotics, which is why the pattern of symptoms matters more than how sore the throat feels.
The medical word for a sore throat is pharyngitis, meaning inflammation at the back of the throat. It is one of the most common reasons people seek care. The useful skill is telling the ordinary kind from the kind that needs testing or urgent attention. This guide covers the usual causes, the clues for each, comfort measures that health services recommend and the warning signs that matter.
Viral infections are the most common cause
The NHS lists colds and flu among the usual causes of a sore throat, and the CDC notes that a cough and runny nose point toward a virus rather than strep. A viral sore throat tends to come with company:
- A runny or blocked nose and sneezing
- A cough or hoarse voice
- Red or watery eyes
- Mild aches and tiredness
- A low fever, or none at all
The throat discomfort is usually worst in the first few days and then fades while the cold symptoms take over. Antibiotics do not work against viruses and do not speed recovery, which is why they are normally not prescribed for a typical sore throat. A less common viral cause is glandular fever (mononucleosis), which can cause a very sore throat with marked tiredness that lasts well beyond a week. If tiredness is severe or the throat is not settling, see a doctor.
Strep throat and other bacterial causes
Group A streptococcus bacteria cause strep throat, which the CDC describes as very contagious. Compared with viral sore throats, strep is the minority cause, but it matters because it can be treated with antibiotics, which help people feel better sooner.
Features the CDC lists for strep include:
- A sore throat that came on very quickly
- Pain when swallowing
- Fever
- Red, swollen tonsils, sometimes with white patches or streaks of pus
- Swollen glands at the front of the neck
- Usually no cough, no runny nose and no hoarseness
Children may also have headache, stomach pain or vomiting, and sometimes a rash. Strep cannot be confirmed by looking at the throat. Clinicians use a rapid test, a throat culture or both. Never take leftover antibiotics or ask for them without a test, and if a clinician prescribes a course, take it as directed. Tonsillitis, an inflammation of the tonsils, can be viral or bacterial, and a clinician can tell you which.
Irritation and environmental causes
Not every sore throat is an infection. Common non-infectious causes include:
- Dry air. Heated indoor air in winter, and sleeping with the mouth open, can leave the throat scratchy on waking, easing through the day.
- Smoke and fumes. The NHS lists smoking as a cause. Tobacco smoke, vaping, wood smoke and strong chemical fumes can all irritate the throat.
- Heavy voice use. Shouting, teaching or singing for hours can leave the throat raw. Laryngitis, an inflamed voice box, often brings hoarseness.
- Mouth breathing. A blocked nose pushes people to breathe through the mouth, which dries the throat overnight.
If the pain follows a place or activity, such as being better on holiday or worse at one workplace, that pattern is a strong clue.
Allergies and post-nasal drip
Hay fever and other allergies cause mucus to drain from the back of the nose down the throat. That constant trickle irritates the lining and leads to throat clearing, a tickle and sometimes a lingering cough. Clues that point toward allergy rather than infection include itchy eyes or nose, repeated sneezing, clear mucus, a seasonal pattern and no fever. If a cough is part of the picture, the guide to when a cough is lingering too long explains how duration changes the question.
Acid reflux
When stomach acid travels upward it can irritate the throat. Sometimes there is no obvious heartburn. Reflux-related soreness tends to be mild and persistent, with frequent throat clearing, a feeling of a lump in the throat, hoarseness or a sour taste, often worse in the morning or after large or late meals. Fever and swollen glands are not usual with reflux. A throat that stays sore for weeks without cold symptoms is a reason to see a doctor, who can look at reflux and other causes.
Comparing the common causes
| Cause | Typical clues | What to do |
|---|---|---|
| Cold or flu virus | Runny nose, cough, mild fever | Rest and fluids; usually better within about a week |
| Strep throat | Sudden painful throat, fever, no cough or runny nose | See a clinician for a test |
| Allergy or drip | Itchy eyes, sneezing, clear mucus, no fever | Ask a pharmacist or doctor about allergy care |
| Dry air or irritants | Scratchy on waking, no fever | Avoid smoke; keep the air comfortable |
| Reflux | Mild long-lasting soreness, throat clearing, hoarseness | Raise with a doctor if it lasts weeks |
What can help while it runs its course
No home remedy cures a viral sore throat, but the NHS suggests several things that ease discomfort:
- Gargle with warm salty water. This is suitable for adults and older children, who must not swallow it.
- Stay hydrated. Drink plenty of cool or warm fluids, and eat soft foods if swallowing hurts.
- Ice lollies or hard sweets can soothe, but should not be given to young children because of the choking risk.
- Rest.
- Over-the-counter pain relief. Paracetamol or ibuprofen can ease pain when taken according to the packet or a pharmacist’s advice. Check with a pharmacist if you take other medicines, and never give aspirin to children under 16.
- Avoid smoke. Smoking makes a sore throat worse and last longer.
Honey in a warm drink is a traditional comfort for adults and children over one year, and it must never be given to a baby under 12 months. Throat sprays and lozenges may give short-term relief, so ask a pharmacist which suit you. For a reminder about checking labels and watching for reactions when you try any product, see side effects to watch for with a new medication.
When to see a doctor
Most sore throats do not need a visit. The NHS advises contacting a GP if:
- The sore throat has lasted longer than a week
- You keep getting sore throats
- You have a lump or mouth ulcer that has lasted three weeks or more
Also seek advice the same day or next day for a sore throat with a high fever and no cough, or if you have a weakened immune system, as that raises the chance of complications. Sore throat with fever is covered in more detail in when to see a doctor for a fever.
Go to emergency care for
Call your local emergency number (for example 911 in the United States or 999 in the UK) or go to the nearest emergency department if there is:
- Difficulty breathing, or a harsh, high-pitched noise when breathing in
- Being unable to swallow, including drooling because saliva cannot be swallowed
- A rapidly worsening, severe sore throat
- Signs of dehydration or being very unwell, with a high fever (the NHS says to call 111 for these if not an emergency)
- A child who is limp, very drowsy or struggling to breathe
Reducing your chances of catching one
Most sore throats follow infections that spread through coughs and sneezes and on hands. Washing hands with soap and water for at least 20 seconds, as the CDC advises, keeping distance from people who are unwell, and staying home when you have a fever all reduce the spread. Not smoking, and managing allergies and reflux with a clinician’s help, reduce the non-infectious kind. More on these routines is in prevention habits that matter most for everyday health.
This article is general information, not medical advice. Talk to a qualified clinician about your own situation.
Where this comes from
This guide is based on the NHS patient guidance on sore throat (causes, self-care, when to call a GP, 111 or 999) and the CDC’s information on strep throat, including its symptoms, testing and treatment, and on the CDC handwashing guidance. Guidance and services change over time and differ by country, so check the current advice from your own health service.