My cheek is swollen: is it a tooth, a salivary gland or an allergy?

The cheek is a soft area lying between the molars of the upper jaw and the skin of the face. Inside it are fatty tissue, part of the chewing muscles and the duct of the large salivary gland in front of the ear. To understand where a swelling is coming from, four routes need thinking about separately: infection spreading from a tooth, inflammation of the salivary gland, a knock, and swelling caused by an allergy or a medicine. Each has its own signature.

With swelling from a tooth, the story usually starts with pain. Among the symptoms of a dental abscess, the NHS lists intense pain in a tooth or the gum, sensitivity to hot and cold, a bad taste in the mouth, redness and swelling in the face or jaw, difficulty opening the mouth and a high temperature. The StatPearls text reviewing odontogenic infections of the face explains that the direction an infection spreads in is decided by which side of the bone the root tip sits on; if the root of an upper molar lies above the line where the cheek muscle attaches to the bone, the infection can spread into the cheek, and infection from the lower molars can also reach the cheek through the outer surface of the bone. So if painful swelling on one side of the cheek comes together with toothache on the same side that has lasted for days, the source is most likely that tooth.

Swelling from a salivary gland sits in a different place. The large salivary gland in front of the ear (the parotid) extends from the back of the cheek to the front of the ear and towards the angle of the jaw; the swelling sits in this area, lifting the earlobe slightly. MSD Manuals describes bacterial inflammation of a salivary gland as fever, chills, pain and swelling on that side of the face, reddening of the skin and sometimes pus coming from the gland's duct; it writes that most of these infections are seen in people whose saliva flow is blocked by a stone or whose saliva is greatly reduced. In a gland blocked by a stone, the swelling gets worse with eating, especially when eating something that increases saliva.

Mumps (parotitis) is inflammation of the same gland caused by a virus. The NHS describes the main symptom of mumps as painful swelling of the cheeks and neck that increases over a few days; the swelling usually starts on one side of the face and then moves to the other, sometimes staying on one side only, and it can cause earache and difficulty chewing and swallowing. Symptoms can start a few days before the swelling. When mumps is suspected, the NHS advises seeing a GP and staying off work or school for at least 5 days after the swelling starts.

The signature of allergic swelling (angioedema) is speed. The NHS defines angioedema as sudden swelling of an area of the body; on the face it particularly affects the lips, tongue and eyelids, and if it is caused by an allergy there is often a raised, itchy rash with it. While a dental abscess grows over hours and days, angioedema can come on suddenly and is not linked to any particular tooth. The NHS states that there is also a non-allergic type, most often linked to ACE inhibitor medicines used for blood pressure. If you take one of these medicines and your lip or cheek has swollen for no reason, make sure you tell your doctor.

With swelling after a knock or a fall to the cheek, bleeding and fluid can build up in the tissue, and bruising can follow. The real question is whether the bone underneath has been affected. If after a knock your teeth do not meet the way they used to, or there is numbness in the cheek or upper lip, double vision or a clearly restricted mouth opening, an emergency assessment is needed the same day.

Then there is expected swelling: after a tooth extraction, especially a wisdom tooth extraction. The NHS writes that after wisdom tooth removal there may be some pain and swelling for up to 2 weeks, that the swelling should start to go down after 1 or 2 days, and that bruising on the cheek and stiffness in the jaw can be seen. What tells them apart is the direction: normal swelling peaks in the first few days and then goes down. Swelling that grows again after a few days instead of going down, and comes with a high temperature and a bad taste, suggests infection; the NHS asks for an urgent dental appointment for pain and swelling that are severe or getting worse and do not respond to painkillers.

The general emergency threshold for a swollen cheek, meaning the situations where the swelling affects the eye or the neck or the mouth will not open, is explained in detail on our facial swelling page. This page focuses on telling the sources apart. But two thresholds apply in every case: for a dental abscess, the NHS counts struggling to breathe, speak or swallow, a swollen eye and problems with vision, a lot of swelling inside the mouth, and not being able to open the mouth as criteria for A&E; for angioedema, it gives sudden swelling of the lips, mouth, throat or tongue as a criterion for 999, which in Turkey means 112.

The two lists below do not make a diagnosis; they send you to the right door. The items on the first list point to the dentist, those on the second to another door or to A&E.

The first thing looked at is not the diagnosis but the danger. Then the location and speed of the swelling, and the symptoms that come with it, point to the source.

1. 1

   Emergency signs first: stop and go to A&E

   If your lips, tongue or throat have suddenly swollen, you are struggling to breathe, speak or swallow, your eye is swollen or painful, your vision has suddenly got worse, you cannot open your mouth, or you have suddenly become lightheaded, dizzy or fainted, call 112 or go to A&E. The NHS advises not driving yourself to A&E and taking the medicines you are on with you. If you have been given an adrenaline auto-injector before, use it as the NHS advises.

2. 2

   How fast the swelling came, and what came before it

   Did it come on within minutes, or grow over hours and days? Beforehand, was there toothache, a cold, a knock, an extraction or a newly started medicine? Does it get worse with eating? These answers often separate the four routes before the examination does.

3. 3

   Where the swelling is and how it feels

   Warm, painful swelling at the front of the cheek, level with the upper molars, suggests a tooth; swelling that runs from in front of the ear to the angle of the jaw suggests the salivary gland; soft, itchy swelling that also affects the lip and eyelid suggests an allergy.

4. 4

   Examining the inside of the mouth, and tests on the teeth

   The teeth on the side of the swelling are checked for decay, fractures and deep pockets, and tapping and cold tests are done. The duct of the gland in front of the ear opens into the inside of the cheek, level with the upper second molar; the dentist gently presses on the gland from the outside and looks at the fluid coming from the duct.

5. 5

   Imaging

   If a dental source is suspected, an X-ray is taken, and a CT scan if needed. If the salivary gland or a lump that can be felt is suspected, ultrasound or CT is used.

6. 6

   Treatment or referral according to the source

   For a dental abscess, draining the pus and treating the source; for a salivary gland infection, fluids, warmth, massage and antibiotics if needed; for mumps, supportive care; for angioedema, finding the trigger and allergy medicines.

Once the cause behind the swelling is found, the work to be done becomes clear.

The points below are the wrong decisions we come across most often with this complaint.

The time varies with the source; the plan of the clinician treating you takes priority.

1. After drainage of a dental abscess

   Because the pressure drops, the throbbing pain eases quickly; the swelling in the cheek goes down more slowly, over a few days. For this period the NHS recommends soft food, a soft toothbrush, and avoiding very hot or cold food.

2. After a tooth extraction

   According to the NHS, the swelling starts to go down after 1 or 2 days, the pain and swelling can last up to 2 weeks, and there may be bruising on the cheek and stiffness in the jaw.

3. With mumps

   The NHS writes that the illness usually gets better within 2 weeks, and that the swelling can increase over a few days.

4. With angioedema

   Once the trigger is removed, and with treatment, the swelling usually goes down. If it keeps coming back, follow-up with a doctor is needed to look for the cause.

We do not give a single figure here, because behind a swollen cheek there may be swelling after an extraction that needs no treatment, an abscess that calls for root canal treatment, or a salivary gland or allergy picture that falls outside dentistry. These are the items that determine the scope:

The source of the swelling

A tooth, a salivary gland, a knock and an allergy are entirely different routes and the field of different clinicians.

How severe the picture is

A drainage done from inside the mouth and a widespread infection needing monitoring in hospital are not assessed within the same scope.

Whether the tooth can be saved

Root canal treatment with a crown on top, and extraction followed by filling the gap, are separate plans.

The need for imaging

In most dental pictures an X-ray is enough; if a salivary gland problem or a lump is suspected, ultrasound, and with widespread infection, a CT scan, is needed.