Toothache Causes — Why a Tooth Hurts

A toothache rarely comes out of nowhere. There is usually an underlying reason, and the type of pain you are feeling — sharp, dull, throbbing, triggered by hot or cold — can give a good clue to what is happening. This page walks through the most common causes so you have a calmer picture of what may be going on before you come in.

If a tooth is severely painful, swollen, or keeping you awake, please see our severe toothache page or book an urgent appointment online.

What toothache can feel like

Tooth pain shows up in many ways, and the pattern often matters more than the intensity. You may notice:

A sharp pain when you bite down on something
A jolt when something hot or cold touches the tooth
A dull, lingering ache that comes and goes
Throbbing pain that gets worse when you lie down
Pain that wakes you at night
Tenderness when you tap the tooth
A feeling that one tooth is "higher" than the others
Swelling around the gum or face

Sharp pain that disappears as soon as the trigger is removed often points to sensitivity or a crack. Pain that lingers after a stimulus, builds up, or wakes you up usually means the nerve is involved and needs attention sooner rather than later.

The most common causes of toothache

Tooth decay

Decay is the most common reason a tooth starts to hurt. Bacteria break through the outer enamel, and once they reach the softer dentine underneath, the tooth can become sensitive to sweets, cold, and pressure. Caught early, decay is usually treated with a filling. Larger areas may need a crown, and decay that reaches the nerve usually needs root canal treatment.

A cracked tooth

Cracked teeth are a common source of sharp pain on biting, particularly on back teeth. The crack can be tiny and not visible from the surface. Cold may also trigger discomfort. Treatment depends on how deep the crack goes — see our cracked tooth page for more.

A dental abscess

An abscess is a localised collection of pus, usually caused by an infection at the root of a tooth or in the gum. It tends to cause throbbing, build-up pain, sometimes with swelling, a bad taste, or a pimple-like spot on the gum. An abscess needs prompt attention — see our dental abscess page.

Sensitive teeth

Sensitivity is short, sharp pain triggered by cold, sweet, or sour foods. It is most often caused by exposed dentine at the gum line or by worn enamel. It usually settles between triggers and is rarely associated with swelling. Our sensitive teeth page goes through the causes and the home and in-chair options.

Grinding and clenching (bruxism)

Grinding teeth at night can leave them sore, dull, and tired-feeling in the mornings. You may also notice headaches or jaw pain. A nightguard can protect the teeth and reduce the load on the jaw.

Gum issues

Inflamed or receding gums can cause discomfort and sensitivity, especially around a particular tooth. Persistent bleeding when brushing or flossing is worth investigating — our gum disease treatment page covers the assessment and management.

An old or failing filling

Fillings do not last forever. As they wear, leak, or fracture, decay can develop underneath and the tooth becomes sensitive. Our replacing old fillings page goes through when replacement makes sense.

Wisdom-teeth pressure

Erupting or impacted wisdom teeth can cause aches at the back of the mouth, soreness when biting down, or repeated gum infections (pericoronitis). See our wisdom teeth hub for more.

Sinus pressure

The roots of the upper back teeth sit very close to the maxillary sinuses. When the sinuses are inflamed — for example with a cold, hayfever, or a sinus infection — pressure can refer down to the teeth and feel like toothache. The pain often affects several teeth at once, gets worse when you lean forward, and settles when the sinus issue clears.

Trauma

A recent knock, fall, or hard bite can leave a tooth bruised, sore, or cracked. See our broken tooth page if the tooth has visibly chipped.

Referred pain

Pain in the teeth is sometimes coming from somewhere else — the jaw joint (TMJ), nearby muscles, or even a tooth on the opposite side. We can usually narrow this down with examination and imaging.

What you can do at home before your appointment

Take over-the-counter pain relief at the recommended dose
Use a cold pack on the cheek for 10–15 minutes at a time
Rinse with warm salt water once or twice a day
Avoid hot, cold, sugary, or hard foods on that side
Keep brushing gently — clean teeth tend to be more comfortable than ones with food packed around them
Avoid lying flat if pain worsens — try propping your head up

Home care can settle minor flare-ups, but the underlying problem will still need to be addressed. If pain persists for more than a day or two, book in.

When to seek urgent care

Call or book in promptly if you notice:

Swelling in the face, jaw, or under the chin
Difficulty swallowing or breathing — go to an emergency department
Fever alongside dental pain
Pain that wakes you at night or does not respond to over-the-counter pain relief
A bad taste, a pimple on the gum, or visible pus

For after-hours flare-ups, our after-hours dental care page explains what to do until you can be seen.

What to expect at your appointment

A toothache visit is short and focused. We will:

Ask when the pain started and what triggers it
Examine the tooth, the surrounding teeth, and the gums
Take targeted digital X-rays where helpful
Use a cold test or a bite test if we need to identify which tooth is involved
Explain the cause and the options in plain language
Settle the immediate problem and book any follow-up treatment

Toothache FAQs

Will the pain go away on its own?

Sensitivity sometimes settles, but pain coming from decay, a crack, or an infection rarely resolves without treatment. Mild discomfort is worth booking in for a check; severe, swelling, or build-up pain is urgent.

Why does my toothache feel worse at night?

Lying down increases blood pressure around the head, which can intensify throbbing pain from an inflamed nerve. Propping your head up may help while you wait to be seen.

Can sinus problems really cause toothache?

Yes. The upper back teeth sit just below the sinuses, and sinus inflammation can refer down. The pain usually involves several teeth, feels dull and pressure-like, and shifts when you lean forward.

I have no visible cavity but my tooth still hurts — why?

Cracks, decay between teeth, gum recession, sinus issues, and grinding can all cause pain without anything obvious on the surface. Imaging and a thorough exam usually identify the cause.

Can I just take pain relief and wait?

You can manage minor discomfort short-term, but pain that persists, builds up, or comes with swelling needs assessment. Untreated infections can spread, and a cracked tooth often gets worse the longer it is left.

What if my child has a toothache?

Treat it the same way — gentle pain relief, soft cool foods, and a prompt dental visit. Our children’s dentistry hub covers what an appointment looks like for younger patients.

Will I need a root canal?

Only if the nerve inside the tooth is inflamed or infected beyond repair. Many toothaches are settled with a filling or by addressing sensitivity or gum issues. Your dentist will explain the options after examining the tooth.

Related information

Book a toothache appointment

If a tooth has been bothering you for more than a day or two, it is worth getting it checked while the problem is still small. Book online or phone the practice during business hours.