All can be unsettling, but which ones matter and which – if any – can you safely ignore? Dr Mel Wynne-Jones shares her expert advice

Blood pressure

Feeling a bit dizzy is quite common but if it soon passes, we may be tempted to ignore it. However, dizziness comes in many forms, and some have serious causes.

It can also trigger falls, especially in older people.

Your GP will want you (or someone who saw it happen) to describe exactly what happened. A phone video can help, if you have one of the incident. Did the room truly ‘spin’, did you feel light-headed or faint, or actually black out or lose consciousness?

Did you have any other symptoms in the minutes, hours or days beforehand or afterwards, had you taken any medication or do any relatives have relevant medical issues? You may need blood tests, a heart tracing (ECG) and scan (echocardiogram), and/or a brain electrical tracing (EEG) or scan.

Simple faints

Known as vasovagal, faints, these can be triggered by the sight of blood, standing for too long, pain, strong emotion, severe coughing, or getting up at night to urinate. You may notice nausea, a rushing sound, or darkening vision, faintness, or briefly lose consciousness.

You’ll look pale and sweaty and have a slow pulse and low blood pressure. But you should quickly feel better, if a bit wobbly (see tips on how to help, below).

Blood pressure and heart conditions

Natural reflexes boost our blood pressure when we stand up, to maintain blood flow to our brains, but these become less effective with age, or if you tend to have low blood pressure you may feel light-headed for a few seconds on standing.

This postural hypotension can be exaggerated by dehydration, high blood pressure pills or heart disease, or as a side effect of drugs used for incontinence, depression and other conditions.

Medical conditions that lower blood pressure, such as shock or Addison’s disease (underactive adrenal glands), can also cause faintness or fainting. Heart attacks and abnormal heart rhythms lower the heart’s output.

You may notice palpitations, pain, breathlessness or sweating, as well as faintness.

Neurological problems

If you lose consciousness after a head injury, get a medical check, even if you feel OK, to rule out brain bleeding (although bruising or concussion is more likely). Migraine, strokes and brain tumours can occasionally trigger dizziness or unconsciousness, as can epilepsy.

A grand mal fit may make someone cry out and fall. Stiffness is followed by rhythmic shaking, and sometimes tongue-biting or incontinence. Afterwards, they may be confused. If it’s a first fit, or lasts more than five minutes, call 999.

Other causes

Anaemia (‘thin’ blood), chemical disturbances and alcohol/drugs can make you feel tired as well as dizzy. Earwax and infections may cause mild wooziness – if the room seems to spin (vertigo), seek medical help.

Viral infections of the inner ear (‘labyrinthitis’) can also cause vertigo; you may vomit or lose your balance and will need medication. Benign tumours of the hearing nerve can cause hearing loss and tinnitus as well as vertigo.

Anxiety often causes dizziness or even tingling sensations if you hyperventilate/overbreathe, so try to slow your breathing.

4 ways to help if somebody has passed out

1. If someone is unconscious, check for traffic, electricity and other risks before helping. Call 999 or send somebody else to do so.

2. Check for breathing and a pulse, and put them in the recovery position if you know how, and there’s no neck/spine injury (see nhs.uk).

3. If they haven’t actually fainted, encourage them to sit or lie down; raising their legs helps in fainting and shock. Use coats or blankets to keep them warm until they’re back to normal.

4. Write down what you saw, and encourage the person to seek medical advice.