Numbness on one side of the face: causes, red flags and when to get it checked

The skin of the face is supplied by the three branches of the trigeminal nerve. Numbness can arise from the nerve itself, from the brain pathways that process it, or from local problems in the teeth, jaw or sinuses. Because stroke can cause sudden one-sided facial numbness, onset speed is the first thing to establish.

• Dental work, abscess or wisdom tooth problems irritating the nerve in the jaw or cheek.

• Migraine with aura: numbness spreads gradually over minutes, often with visual shimmers and followed by headache.

• Anxiety and over-breathing, causing tingling around the mouth and in the hands.

• Sinusitis or facial trauma, with local swelling and tenderness.

• Trigeminal neuralgia: severe, brief electric-shock pains in the face, sometimes with altered sensation; numbness suggests another cause needs excluding.

• Shingles on the face, preceded by burning pain and numbness, then a blistering rash in a band.

• Bell palsy, where facial weakness is the main feature, sometimes with a sense of numbness.

• Transient ischaemic attack or stroke, multiple sclerosis, and, rarely, tumours or aneurysm pressing on the nerve.

Sudden onset, facial droop, slurred speech, arm or leg weakness, vision loss, persistent numbness with hearing loss or swallowing difficulty, a history of cancer, or numbness that gradually spreads or does not resolve are all concerning.

• Call 999: sudden facial numbness or droop, slurred speech, weakness in an arm or leg, confusion or vision loss.

• Same-day GP or NHS 111: a painful blistering rash on one side of the face or near the eye (shingles can threaten sight).

• GP within days: numbness lasting more than a few days, or with hearing change or double vision.

• Dentist: facial swelling, a toothache or recent dental work with numbness.

Doctors ask how fast it started, the exact area, whether the lips, tongue or inside of the mouth are affected, accompanying headache, visual changes, dental history, previous shingles or neurological episodes. They test sensation in all three facial areas, facial strength, eye movements, hearing, corneal reflex, and check blood pressure and heart rhythm.

• MRI brain and brainstem, sometimes with contrast: to look for stroke, demyelination or a lesion on the nerve.

• CT or MR angiography and carotid imaging: when TIA or stroke is suspected.

• Blood tests and ECG: to look for stroke risk factors including diabetes, cholesterol and atrial fibrillation.

• Dental X-rays: if a tooth or jaw cause is suspected.

There is no self-care for sudden numbness; it requires assessment. For a recognised migraine aura, rest and your usual migraine plan apply. Protect the numb area from burns and avoid biting the cheek or lip until sensation returns. Good dental hygiene and early dental review help prevent nerve irritation from infection.

The NHS route for suspected stroke is 999 and a stroke unit; for non-urgent cases it is a GP, then neurology. Private neurology consultations and MRI are available directly.