Emergency dental symptoms
Headache from a dental infection: how a tooth causes it and what to do
A headache that sits on one side, comes with a tooth that is tender, and gets worse when you lie down is often a tooth problem rather than a head problem. Here is how to tell, and when it needs more than a dentist.
Clinically reviewed by Dr Ibraheem Ijaz, Principal Dentist · GDC 301711 · Last reviewed April 2026
How a tooth infection causes a headache
Every tooth, the face and the front of the scalp are all wired to one nerve, the trigeminal, through three branches: forehead and eye, cheek and upper teeth, jaw and lower teeth. All three feed into the same relay in the brainstem. When an infected tooth fires pain signals for hours on end, that relay becomes overloaded and the pain spills over into the neighbouring branches. An abscess on an upper molar is then felt in the cheekbone, the temple and behind the eye; one on a lower molar in the jaw, the ear and the side of the head. Your brain is reporting the right nerve and the wrong address.
There is a second route for the upper back teeth. Their roots sit against the floor of the sinus, sometimes separated from it by a layer of bone thinner than an eggshell and sometimes by nothing but the sinus lining. An abscess at one of those root tips can break into the sinus, and you get a heavy, pressure headache across the cheek and forehead that worsens when you bend forward, exactly like sinusitis, because it is sinusitis, started by a tooth.
Upper molar or premolar abscess.
Lower molar or wisdom tooth.
Clenching against the pain.
A cracked tooth.
Telling a dental headache from other headaches
A dental headache is on one side, and somewhere on that side there is a tooth that is tender to tap or bite on, or reacts to hot. It is worse at night and lying flat. There may be a bad taste, a swollen gum or a tooth that feels tall. Painkillers help for a while. There is no aura, no sickness and no sensitivity to light. A quick check you can do at the bathroom mirror: tap each upper and lower back tooth on the painful side with a fingernail. If one of them makes you wince, you have probably found the cause.
Tension headache.
Migraine.
Sinusitis after a cold.
Cluster headache or trigeminal neuralgia.
Signs the infection is spreading
Call today.
Same day.
A&E now, or 999.
Managing the pain until you are seen
- Ibuprofen and paracetamol as directed on the packet, together if you can take both. Ibuprofen works on the inflammation as well as the pain.
- Sleep propped up. Lying flat raises the pressure in the head and in the abscess, and is why the headache peaks at night.
- A cool compress on the cheek or temple. No heat on the face; it encourages the infection to spread towards the skin.
- Warm salt water rinses, and keep hot food and drink away from the tender tooth.
- Do not take leftover antibiotics from a previous prescription. Half a course at the wrong dose does not clear the infection and makes it harder to treat. Our guide to temporary fixes before your appointment has more.
Finding and treating the source tooth
The emergency examination is £30 including X-rays and takes about 15 minutes. We ask about the pattern of the headache, check your temperature, look for swelling, check your eye movements and how far you can open, then tap every upper and lower back tooth on that side, cold-test them and use a bite test if a crack is possible. Pressing on the cheekbone and asking you to bend forward tells us whether the sinus is involved. A digital X-ray shows the dark shadow of an abscess at a root tip. Where the roots sit close to the sinus, or the ordinary X-ray is unclear, a CBCT scan (£150) gives a 3D picture that shows whether the infection has broken through into the sinus.
The treatment is the treatment for the abscess, because the headache is a symptom of it. The tooth is drained the same visit where possible: stage 1 of an emergency root canal (from £200) if the tooth can be kept, or an extraction (£120–£260) if it cannot. Once the pressure is released, the referred headache usually fades within a day or two. Antibiotics are added when the infection has spread into the face or the sinus or you have a fever, which is often the case by the time a headache has developed, but they are given alongside drainage, not instead of it. Our antibiotics guide explains why.
Fees are agreed in writing before treatment. Visits after 6pm on weekdays and at weekends carry an additional out-of-hours charge.
| Treatment | Fee (from) |
|---|---|
| Emergency examination including X-rays | £30 |
| CBCT 3D scan | £150 |
| Emergency root canal stage 1 | £200 |
| Completed root canal treatment | £450 |
| Extraction | £120–£260 |
When it is more than a dental problem
Infection from an upper tooth can, very rarely, travel along the veins around the eye into the skull, and infection anywhere in the face can reach the lining of the brain. The warning signs are the same: a severe headache with fever, a stiff neck, confusion or drowsiness, vomiting, double or lost vision, or an eye that swells or stops moving. Those need A&E immediately, not a dental appointment. Separately, a headache that reached full force within seconds, a headache in someone over 50 with a tender scalp and jaw pain on chewing, or a new headache with weakness or slurred speech are medical emergencies in their own right. Our guide to what counts as a dental emergency draws the line in more detail.
Questions, answered
Common questions
Can a tooth infection cause pain behind the eyes or in the forehead?
Yes. Upper back teeth share a nerve branch with the cheek and the area around the eye, and their roots sit against the sinus, so an abscess there is often felt as pressure behind the eye or across the forehead on that side.
Will antibiotics alone stop a headache from a tooth infection?
They may ease it for a while, but the abscess is still there and the headache comes back when the course ends. The tooth needs draining, by root canal or extraction. Antibiotics are used alongside that when the infection has spread.
How quickly does the headache improve after the tooth is treated?
Usually within 24 to 48 hours of the abscess being drained, as the pressure and the constant nerve signals stop. Muscle headache from clenching can take a few more days to ease.
Can a tooth infection spread to the brain?
Very rarely, yes, which is why a severe headache with fever, stiff neck, confusion, vomiting or changes in vision alongside a dental infection needs A&E at once. The vast majority of dental abscesses are drained long before that point.
Why is my headache worse when I lie down?
Lying flat raises the blood pressure in the head, which raises the pressure inside an abscess and the sinus. Sleeping propped on two pillows takes some of it off, and is one of the small clues that the headache is coming from a tooth.
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