Can a tooth cause a sore throat on one side?

The lower wisdom teeth sit in the very back corner of the mouth, a few centimetres from the entrance to the throat. Because inflammation around this tooth is very close to the tonsil area and the pharynx, people sometimes feel it not as "toothache" but as "this side of my throat hurts, and it goes to my ear when I swallow". That is why they may go first to a pharmacy or their GP rather than a dentist.

The first cause coming from the mouth is pericoronitis: inflammation that develops when food debris and bacteria collect under the gum flap covering a partly erupted tooth, most often a lower wisdom tooth. In a study cited by StatPearls, 95 per cent of cases involved lower wisdom teeth. In the acute picture there is severe pain at the back teeth, red and swollen gum, a bad taste, pain on swallowing and difficulty opening the mouth. Its treatment is explained in detail on the pericoronitis page.

The second cause from the mouth is an abscess spreading from a molar. Among the symptoms of a dental abscess, the NHS lists intense pain in a tooth or the gum, a bad taste in the mouth, difficulty opening the mouth and chewing, swelling in the face or jaw, swollen glands in the neck and a high temperature. Infection coming from the lower molars can also move towards the tongue side and the side of the pharynx. People may notice the pain on swallowing on that side of the throat before they notice the toothache.

The commonest non-dental cause is tonsillitis. The NHS lists its symptoms as a sore throat, difficulty swallowing, a high temperature, headache and earache, and writes that the symptoms usually get better within 3 to 4 days. Tonsillitis is mostly on both sides; one side being clearly more painful and swollen shifts the picture towards an abscess forming around the tonsil.

An abscess around the tonsil (peritonsillar abscess, or quinsy) is the urgent face of a one-sided sore throat. The NHS describes it as a collection of pus between the tonsil and the wall of the throat. MSD Manuals writes that it is seen most in teenagers and young adults, that swallowing often causes severe pain that spreads to the ear, that the uvula can swell and be pushed to the side opposite the abscess, that spasm of the chewing muscles stops the mouth from opening, that the person speaks in a muffled voice "as if there were a hot potato in the mouth", that they drool, and that they tilt their head towards the side of the abscess to ease the pain.

What these two pictures, dental inflammation in the mouth and a tonsil abscess, have in common is difficulty opening the mouth and pain that spreads to the ear. The signs that tell them apart have to do with location. In the dental picture, the swelling and tenderness are around the very back tooth, in the gum and along the edge of the jaw; pressing on that tooth or gum makes the pain worse, and there is a bad taste in the mouth. With a tonsil abscess, the swelling is inside the mouth, over the tonsil and on the soft palate; the uvula has shifted to the side and the voice has changed. Checking in a mirror whether the uvula is in the middle can give a clue; but its looking central does not rule out an abscess, and the decision belongs to the examination.

Infection from either source can move on into the deep spaces of the neck. MSD Manuals states that an abscess forming in the side wall of the throat (the parapharyngeal space) takes up more room and is more dangerous than a tonsil abscess. For a sore throat, the NHS also points straight to A&E for difficulty breathing, not being able to swallow, drooling, a high-pitched sound as you breathe, and severe symptoms that are getting worse quickly. With these symptoms, whether the source is a tooth or a tonsil stops mattering.

Finally, a one-sided throat complaint that does not go away. Cancer Research UK counts hoarseness lasting longer than 3 weeks as one of the commonest symptoms of laryngeal cancer and advises seeing a doctor in that case; the same source stresses that hoarseness is most often due to harmless causes such as laryngitis. Among the symptoms of laryngeal cancer, the NHS lists pain when swallowing, a lump in the neck and earache that does not go away; for mouth cancer, too, it gives a mouth ulcer lasting longer than 3 weeks as a reason to see a doctor. One-sided throat and ear pain that has gone on for weeks without any sign of infection, especially in someone who smokes, needs an ENT examination.

The first list shows the signs that suggest the pain is coming from the mouth, from the very back tooth; this picture does not clear at home, but it is sorted out by going to a dentist the same day. If any item on the second list applies, what you need is not a dentist but A&E or an ENT specialist.

The sequence starts with danger, then works down to where the pain comes from. A one-sided sore throat falls within the field of both the dentist and the ENT specialist; these steps decide which door is the right one.

1. 1

   Emergency signs first: stop and go to A&E

   Not being able to swallow, drooling, difficulty breathing, a high-pitched sound as you breathe, not being able to open your mouth, swelling in the mouth or neck that is growing fast. If any of these is present, you do not wait for the tooth-or-tonsil question to be settled; the NHS advises not driving yourself to A&E, having someone take you or calling an ambulance, and taking the medicines you are on with you.

2. 2

   The story of the pain

   Did the pain come after toothache, or with a cold? Is your wisdom tooth partly erupted? Has your mouth been opening less since the morning? Has your voice changed? Do you have a high temperature? How long has the pain been going on? These questions often point to the source before the examination does.

3. 3

   Examining the inside of the mouth

   The gum around the very back teeth, the gum flap, the molars on the painful side and the tooth in the opposite jaw are examined. In the same examination the tonsils, the soft palate and the position of the uvula are looked at; a uvula pushed to the side points to a tonsil abscess.

4. 4

   Testing the teeth, and an X-ray

   A cold test and light tapping are done on the suspect tooth; an X-ray is taken if needed. The position of the wisdom tooth, whether it can come through, and whether there is infection at the root tip are established from this image.

5. 5

   Examining the neck

   The glands under the jaw and in the neck, and where the swelling is and how it feels, are checked. A one-sided lump that is hard, painless and has not got smaller for weeks needs assessment for causes other than infection.

6. 6

   Referral to the right door

   If the source is a tooth, the treatment is done by the dentist. If a tonsil abscess is suspected, an ENT specialist; MSD Manuals writes that the diagnosis is confirmed with ultrasound or CT if needed. For pain and hoarseness that continue without any sign of infection, the place to go is ENT too.

There is no single treatment for a one-sided sore throat; the work changes with the source that is found.

The points below are wrong decisions often seen with a one-sided sore throat.

The timings vary with the source; the plan of the clinician treating you takes priority.

1. Until you reach treatment

   The NHS recommends taking ibuprofen or paracetamol without going over the recommended dose, soft food, plenty of fluids, and avoiding very hot or very cold food. Keep an eye on how far your mouth opens and on your swallowing during the day.

2. After the area under the flap is cleaned or the abscess is drained

   Because the pressure drops, the throbbing pain usually eases quickly and swallowing becomes more comfortable. Mouth opening improves more slowly.

3. With tonsillitis

   The NHS writes that the symptoms usually get better within 3 to 4 days, and that you should see a GP if they have not gone within a week.

4. Once the source is removed

   If the wisdom tooth has been taken out, or root canal treatment on the abscessed tooth has been completed, the recurring sore throat on the same side comes to an end too. If it keeps coming back, the source should be looked for again.

We do not give a single figure here, because behind a one-sided sore throat there may be a viral infection that clears on its own, a wisdom tooth extraction, or an abscess that has to be drained in hospital. These are the items that determine the scope:

What the source is

A picture coming from a tooth is the dentist's field, one coming from a tonsil is the ENT specialist's; the procedures are entirely different.

How severe the picture is

A cleaning done as an outpatient and an abscess needing drainage in hospital and antibiotics into a vein are not the same scope.

The position of the wisdom tooth

Extracting an erupted tooth and the surgical removal of a tooth lying tilted in the bone are different procedures; the X-ray decides this.

How many teeth are affected

A single wisdom tooth problem and a plan covering more than one tooth are not costed the same way.