Fainting: What to Do and When It's an Emergency

If someone faints, lay them on their back, raise their legs and check that they are breathing normally. A faint usually lasts seconds, up to a minute; let the person get up slowly. If they do not come round within a minute, or are not breathing normally, it is an emergency.

When to see a doctor

Now — emergency (999 in the UK, 911 in the US, 112 in the EU):

unresponsive and not breathing normally (occasional gasps are not normal breathing, Resuscitation Council UK) — call and start CPR;
does not come round within a minute (NHS; Mayo Clinic);
has not fully recovered, or finds it hard to speak or move;
chest pain, shortness of breath, or a strong, fluttering or irregular heartbeat before or after — see heart attack signs;
fainted during exercise or while lying down;
shaking or jerking — see what to do during a seizure;
was seriously hurt in the fall, especially the head — see concussion signs;
is pregnant;
has diabetes and it could be low blood sugar — see diabetic emergency.

In the US, MedlinePlus also advises calling 911 when the person is over 50.

Within 24 hours: known heart disease, or a relative who died suddenly at a young age — ask for an urgent assessment (NICE CG109, UK).

Routine, but do not skip it: after any faint, see a GP — "it's probably nothing serious, but it's important to get checked" (NHS). In the US, MedlinePlus advises a doctor's visit for a first faint, frequent faints or new symptoms.

What is happening

A faint (syncope) is a brief loss of consciousness because not enough blood reaches the brain; it starts quickly, lasts a short time and ends with full recovery on its own (European Society of Cardiology, ESC 2018). Consciousness usually returns within 10–30 seconds.

The common reflex faint. A reflex widens blood vessels so blood pressure drops, and/or sharply slows the heart, sometimes with a pause of a few seconds (ESC). Lying flat with the legs raised helps blood return to the brain.

Signs of a low-risk faint (ESC): warning signs first — light-headedness, feeling hot, sweating, nausea; a trigger such as an unpleasant sight, sound, smell or pain, long standing in a stuffy crowded place, eating, coughing, passing urine, or standing up; similar episodes over years with a healthy heart.

Signs of a higher-risk faint (ESC): new chest pain, breathlessness, abdominal pain or headache; fainting during exertion or lying down; sudden palpitations followed by a faint; known serious heart disease. Also important alongside heart disease: no warning or a very short one, sudden death in young relatives, fainting while seated.

Jerks are not always a seizure. Brief irregular twitches are very common during a faint and start after consciousness is lost; confusion afterwards lasts seconds, while after an epileptic seizure it can last minutes (ESC). On the spot a bystander cannot reliably tell them apart, so the NHS advice holds: shaking or jerking means calling 999.

What to do

If you can, help them down to the floor so they do not hit their head.
Lay them on their back and check breathing straight away: tilt the head back, lift the chin, look and listen for breathing (NHS). Not breathing normally — ambulance and CPR; don't spend time on the legs.
Breathing normally — raise their legs on a pillow, bag or chair.
Loosen a tight collar or belt and get fresh air (St John Ambulance; Mayo Clinic; MedlinePlus).
Breathing normally but not coming round — put them in the recovery position and call an ambulance. If they vomit, turn them on their side.
Afterwards: lie for 10–15 minutes (MedlinePlus), then sit, then stand slowly — getting up at once can cause another faint (Mayo Clinic). Water only once they are fully awake and can swallow (IFRC).

Smelling salts are not part of first aid. None of the protocols we read — NHS, St John Ambulance, British Red Cross, Mayo Clinic, MedlinePlus, ESC, IFRC, ANZCOR, ILCOR — mentions ammonia for fainting. We found no evidence that it speeds recovery, and ammonia fumes irritate the eyes, nose, throat and airways: the US FDA (2024) warned against unapproved ammonia inhalants sold for alertness — a different use, but the same substance.

If you feel faint yourself: lie or sit down. Muscle-tensing manoeuvres — crossing and squeezing your legs, squatting, gripping your hands together and pulling — can stop a faint (ILCOR; IFRC; ANZCOR). In a trial they reduced repeat faints (by 39% in relative terms); they work best in people under 60 who get warning signs (ESC).

When this is not the case

Pregnancy: especially after 28 weeks, lay a pregnant woman on her side rather than her back (NHS); IFRC suggests the left side.
Diabetes: a faint or drowsiness in someone on insulin or diabetes tablets may be low blood sugar. If they are unconscious or drowsy, give nothing by mouth, put them in the recovery position if breathing normally, use glucagon if available and call an ambulance (NHS).
Heat and dehydration: see heat stroke versus heat exhaustion and dehydration.

Sources

Checked: 27 September 2026