Bell's palsy: sudden facial weakness, treatment and recovery

The NHS describes Bell's palsy as temporary weakness or lack of movement that usually affects 1 side of the face. NICE Clinical Knowledge Summaries (CKS) define it as an acute, unilateral, idiopathic facial nerve paralysis with rapid onset, in less than 72 hours, and unknown cause. CKS says it affects 20 to 30 people per 100,000 each year and is most common between 15 and 45 years of age.

The NHS notes that Bell's palsy is the most common cause of facial paralysis, but there are many other types of facial palsy. CKS says the diagnosis is made when no other condition is found to be causing the weakness, which is why a clinician checks for other causes.

Facial droop is also a sign of stroke. The NHS says to call 999 if somebody's face droops on 1 side (the mouth or eye may have drooped), a person cannot lift up both arms and keep them there, or has difficulty speaking with slurred or garbled speech. These are signs of a medical emergency and should not wait for a GP appointment.

CKS says features atypical of Bell's palsy require referral to exclude another diagnosis, and that urgent referral should be arranged if the palsy may be caused by an upper motor neurone cause, cancer, acute systemic or severe local infection, or trauma.

The NHS lists the following:

• Weakness on 1 side of the face, or being unable to move 1 side, usually developing over a few days.

• A drooping eyelid or corner of the mouth.

• Drooling.

• A dry mouth and loss of taste.

• A dry or watering eye, and difficulty closing the eye on the weak side.

• Rarely, being unable to move both sides of the face.

CKS adds that both the upper and lower parts of the face are affected, often with a drooping eyebrow and corner of the mouth and loss of the nasolabial fold; ear and behind-the-ear pain on the affected side; difficulty chewing; numbness or tingling of the cheek or mouth; speech articulation problems; and hyperacusis, meaning unusual sensitivity to sound.

The NHS says treatments include a 10-day course of steroid medicine, sometimes with antiviral medicine, eye drops and ointment to stop the affected eye drying out, and surgical tape to keep the eye closed at bedtime. If you cannot close your eye you may need treatment to prevent damage to your vision.

CKS says prednisolone should be considered for people presenting within 72 hours of the onset of symptoms, that antiviral treatment alone is not recommended but may have a small benefit alongside a corticosteroid, and that specialist advice is advised if it is being considered. It advises using lubricating drops by day and ointment at night, and taping the eye closed at bedtime with microporous tape if you cannot close it. Take steroid courses exactly as prescribed.

The NHS says symptoms should improve within 6 months, and that you should go back to a GP if there is no improvement after 3 weeks. Some people have permanent facial weakness with symptoms such as facial pain around the jaw and behind the ear, a constantly watering eye, difficulty eating and drinking, changes in taste and difficulty with loud sounds. The NHS says you will usually only get Bell's palsy once, though rarely it can return, sometimes years later.

CKS lists complications including eye injury, facial pain, dry mouth, intolerance to loud noises, abnormal facial muscle contraction during voluntary movements and psychological effects, and says referral should be considered if aberrant reinnervation symptoms develop 5 months or more after onset.

CKS says routine referral is not needed for an uncomplicated episode in adults, but a specialist should see you if eye symptoms such as pain, irritation or itch develop at any time, atypical features are present, there is no improvement after 3 weeks of treatment, neurological findings worsen or new ones develop, or recovery is incomplete 3 months after onset. Referral may also help if you would benefit from support or counselling for emotional consequences.

The NHS says living with Bell's palsy can make you feel depressed, stressed or anxious, and advises speaking to a GP if it is affecting your mental health. Facial Palsy UK is the organisation the NHS names for further information about facial palsy.

Most people are assessed by a GP or urgent care service within days and managed in primary care. Because the treatment window is short, speed of first assessment matters more than the choice of NHS or private clinic. If recovery is slow, a private neurology, ENT or facial therapy opinion may be sought; ask what specific therapy is being proposed and what evidence supports it.