Numb lip: what causes it, and when is it an emergency?

Feeling in the face is carried by the trigeminal nerve, one on each side. Cleveland Clinic describes its three branches as follows: the upper jaw branch gives feeling to the midface from below the eyes down to above the mouth, to the upper teeth, the palate and the sinuses; the lower jaw branch to the lower teeth, the tongue, the floor of the mouth, the inside of the cheek and the skin below the mouth. In other words, the upper and lower lips get their feeling from different branches, and each side uses its own nerve.

This gives you a map you can draw at home. Using a clean cotton bud or your fingertip, lightly touch the right, left, upper and lower parts of your lip and chin; looking in a mirror, mark with an eyeliner pencil the line where the difference in feeling starts and ends. If the numbness covers one half of the lower lip and the chin on the same side and stops exactly at the midline, the end of the lower jaw nerve (the mental nerve), or the nerve in the lower jaw canal that it continues from, comes to mind. If the upper lip goes numb together with the side of the nose and the cheek, the upper jaw branch stands out. If both lips go numb at once, like a ring around the mouth, the cause considered is not a single nerve but something affecting the body as a whole.

The map has one more option, and it is the most important one. If the numbness is not only in the lip but also in one half of the face, an arm or a leg, or if one side of the face has drooped, the brain is considered rather than a nerve branch. The NHS lists the main symptoms of a stroke as sudden weakness of the face (one side of the face drooping, difficulty smiling), weakness or numbness in one arm and slurred speech; it gives numbness down one side of the body among the additional symptoms. Even if the symptoms pass in a short time, the NHS says to get help immediately.

The commonest and most harmless cause is the numbing injection used in dental treatment. What is surprising here is how long the numbness lasts. In two multicentre studies of 484 people published in the Journal of the American Dental Association, after standard anaesthetics containing a vasoconstrictor, the time for feeling to return, measured by touching the lip every five minutes, came out at a median of 155 minutes for the lower lip and 133 minutes for the upper lip. The time is counted from the end of the procedure. So if you still cannot feel your lip two or three hours after leaving treatment, this is an expected picture.

If the numbness lasts into the next day and you have had a lower wisdom tooth extracted, the nerve in the lower jaw canal (the inferior alveolar nerve) may have been affected. The NHS lists numbness or tingling in the tongue, lip and chin among the risks of wisdom tooth removal and writes that it usually gets better but can last for a few weeks or months. A review of publications from 2009 to 2014 gives the rate at which this nerve is affected after wisdom tooth extraction as roughly 0.35% to 8.4%; being over 24 and the tooth being impacted horizontally are among the factors that raise the risk. The same review states that recovery is the rule and permanent damage is very rare.

With implants, the risk depends on the distance between the tip of the implant and the nerve canal. In a systematic review and meta-analysis published in 2025, no sensory disturbance was seen with implants 2 millimetres or more from the canal, or 1 to 2 millimetres from it. With implants placed 0 to 1 millimetre from the canal, sensory disturbance was reported at a rate of 68%, and with implants entering the canal, 53%. The authors write that a distance of 1 millimetre may be safe and that planning with three-dimensional imaging is needed. How numbness after an implant is followed up is the subject of a separate page.

In people who have been without teeth for many years and wear a lower denture, there is another route. As the jawbone shrinks after the teeth are lost, the opening through which the nerve supplying the lower lip leaves the bone (the mental foramen) moves closer to the upper edge of the bone. In a measurement study of 102 dry jawbones in Greece, this opening lay right next to the edge of the bone in a quarter of the toothless jaws (9 of 36). The authors state that in this position the nerve is exposed to pressure from the denture, and that constant pressure can lead to pain in the face on the same side and numbness in the lower lip.

One picture, however, must be kept apart: new numbness of the lower lip and chin that starts without any dental procedure. In the literature it is called numb chin syndrome. In a review of 102 studies in the Journal of the American Dental Association, this picture was associated with a cancer in 29% to 53% of published cases; the commonest were breast cancer, lymphoma and leukaemia. 28% of patients had first gone to a dentist, and 74% of cases were one-sided. These rates come from published cases, so they do not mean that half of all chin numbness in the population is cancer; but they show that numbness with no explanation needs thorough investigation.

Tingling on both sides around the mouth, like a ring, suggests something else. MSD Manuals writes that a low level of calcium in the blood (hypocalcaemia) causes tingling in the lips, fingers and feet, with muscle cramps added as it progresses; damage to the parathyroid glands during thyroid surgery is one of the known causes. That is why tingling of the lips and fingers starting in the days after thyroid surgery is a symptom to report to the surgical team straight away. A cold sore also starts with tingling in the lip; the NHS writes that a cold sore usually starts with tingling, itching or burning and that blisters appear within 48 hours.

The first list covers pictures that are expected to pass on their own. If even one item from the second list applies, do not wait.

The order deliberately starts with danger. A stroke and a serious allergy are ruled out before a tooth or a nerve is considered.

1. 1

   Face, arms and speech first

   Smile into the mirror: does one side of your face droop? Raise both arms: does one drift down? Say a simple sentence: are the words muddled? If any one of these three signs, which the NHS sums up as FAST, is present, call 112. Call even if the symptoms pass; the NHS also treats symptoms that happened and passed within the last 24 hours as an emergency.

2. 2

   Then swelling and breathing

   If the lip, tongue or throat is swelling, or breathing is getting faster or harder, it may be a serious allergic reaction or angioedema (sudden swelling of the deeper tissue under the skin). That also means 112.

3. 3

   Have you had dental treatment in the last 24 hours?

   If you have, and the numbness is on the side where the injection was given and is easing over a few hours, this is the expected picture. If it is still the same the next morning, or you had an extraction or implant, call the clinician who did the procedure.

4. 4

   Map the numb area

   Touching with a cotton bud or fingertip, mark the edges with an eyeliner pencil and take a photo. One side of the lower lip and chin stopping at the midline, the upper lip and cheek going numb together, or tingling on both sides around the mouth each point to different causes. The photo also helps show whether the area is shrinking over the following days.

5. 5

   Note any accompanying symptoms

   Tingling in the fingers and muscle cramps, recent thyroid surgery, past cancer treatment, new weight loss, a blister on the lip, a blow to the face. Take this list with you when you see a doctor.

6. 6

   See the right clinician

   For numbness that persists after a dental procedure, the clinician who did the procedure or an oral and maxillofacial surgeon; for unexplained chin numbness, your GP and, if needed, neurology; for tingling around the mouth and in the fingers, your GP and a blood test. Questions to ask: which nerve does the numb area match, is imaging needed, and how will recovery be measured?

There is no single treatment for a numb lip. What is done depends on the cause behind the numbness.

The points below are wrong decisions often made with this complaint. We set them out so that you can ask the right questions whichever clinician you see.

The duration depends entirely on the cause. The course below applies to numbness linked to a dental procedure; the plan of the clinician following you takes priority.

1. The first hours

   Numbness from anaesthetic usually wears off within 2 to 3 hours of the procedure; in measurements, a median of 155 minutes for the lower lip and 133 minutes for the upper lip.

2. The next day

   If the numbness is still there, it has lasted longer than expected for an anaesthetic. Tell the clinician who did the procedure; the numb area is recorded, and if there is an implant, a CBCT scan is requested.

3. Weeks and months

   The NHS writes that numbness from a wisdom tooth extraction usually gets better but can last weeks or months. The numb area shrinking at every check-up is a good sign.

4. If recovery stops

   If the area is not shrinking at check-ups or feeling is not coming back at all, ask for an oral and maxillofacial surgery assessment. Reviews state that permanent damage is very rare.

We do not give a single figure here, because behind a numb lip there may be an anaesthetic that passes in a few hours, an affected nerve that has to be followed for months, or an illness that has nothing to do with the teeth. These are the items that determine the scope:

The cause of the numbness

Anaesthetic, an affected nerve, a cold sore or an illness unrelated to the teeth are completely different routes and the field of different clinicians.

The need for imaging

A CBCT scan may be needed when a nerve is suspected after an implant or extraction, and further imaging for unexplained numbness.

The length of follow-up

Because recovery of an affected nerve can take months, the number of follow-up examinations varies.

Additional treatment

Correcting the position of an implant, readapting a denture or a surgical assessment can enter the plan as separate items.