Bell’s palsy vs stroke: why a drooping face is always an emergency first

You should not try to decide between Bell’s palsy and stroke yourself. A face that has drooped on one side can be caused by either, and the safe response is the same: call 999. The NHS Bell’s palsy page makes this the very first line of its advice, listing a face that droops on one side, an inability to lift both arms and keep them there, and difficulty speaking as signs of a stroke, which it calls a medical emergency.

Once a stroke has been ruled out by a clinician, Bell’s palsy is the most common cause of facial paralysis, according to the NHS. It is a temporary problem that is uncomfortable and often alarming but not life-threatening. The reason the comparison matters is that the two look similar at first glance and have very different urgency and outcomes.

Bell’s palsy is temporary weakness or lack of movement that usually affects one side of the face. The NHS lists weakness on one side of the face, or being unable to move that side, that usually develops over a few days, a drooping eyelid or corner of the mouth, drooling, a dry mouth, loss of taste, and a dry or watering eye. You may also find it difficult to close the eye on the weak side. Rarely, both sides of the face are affected.

A stroke is a problem in the brain, not the face. The NHS says that it is when blood stops flowing to part of the brain and can affect things like speech and movement. The facial droop is only one possible symptom, and the NHS lists arm weakness, speech problems, confusion, dizziness and a severe headache among the others.

The table compares what the NHS and the Stroke Association list. Overlap in the first row is the reason for the emergency advice.

The pages from the NHS and the Stroke Association do not offer a self-test that separates the two, and they do not suggest one. The Stroke Association’s FAST test (face, arms, speech, time) is designed to identify the three most common signs of stroke quickly, and says that any one of them is a reason to call 999 straight away, even if it does not seem like much. A drooping face alone is therefore enough.

The NHS stroke advice also says that stroke symptoms can sometimes stop after a short time, so you may think you are fine, and that you should still get medical help straight away. It says to call 999 if you have had signs of a stroke within the last 24 hours, even if they have stopped. The Stroke Association explains that symptoms that last only a short time could be a transient ischaemic attack (TIA), or mini-stroke, which is still a medical emergency and a warning that you are at risk of a stroke.

For Bell’s palsy, the NHS lists a 10-day course of steroid medicine, sometimes with an 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. Treatment is more effective if started early, within 72 hours, which is why the NHS asks for an urgent GP appointment or NHS 111 help as soon as possible after symptoms of Bell’s palsy start.

For stroke, the Stroke Association says ambulance paramedics are trained in stroke and will ensure that the person receives emergency care and specialist treatment. The NHS says it needs urgent treatment in hospital. Recovery from a stroke can take a long time, whereas the NHS says Bell’s palsy symptoms should get better within 6 months, although it can take longer for some people.

The NHS says to go back to a GP if Bell’s palsy symptoms are not getting better after 3 weeks. Some people have permanent facial weakness and symptoms such as pain in the face, around the jaw and behind the ear, a constantly watering eye, difficulty eating and drinking, changes in the sense of taste, and difficulty with loud sounds. It can feel depressing, stressful or anxious, and the NHS says to speak to a GP if it affects your mental health. You will usually only get Bell’s palsy once, although it can rarely come back, sometimes years later. Facial Palsy UK provides information on other types of facial palsy.