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Feeling Faint and Passing Out

Feeling faint is a sensation of dizziness or light-headedness. It may be followed by passing out (loss of consciousness). The cause is usually lack of food or a reduction in blood flow to the brain. A brief episode of feeling faint without other symptoms is not a cause for alarm, but you should consult your doctor if such episodes recur or if you have passed out.

  • Have you had any of the following symptoms?

    • Disturbed vision

      Are any of your symptoms still present?

      • Symptoms present
        • Possible cause It is possible that you have had a stroke.

          Medical help EMERGENCY! Dial 999/112 and ask for an ambulance.

      • Symptoms no longer present
    • Numbness, tingling, or weakness in any part of the body

      Are any of your symptoms still present?

      • Symptoms present
        • Possible cause It is possible that you have had a stroke.

          Medical help EMERGENCY! Dial 999/112 and ask for an ambulance.

      • Symptoms no longer present
    • Confusion

      Are any of your symptoms still present?

      • Symptoms present
        • Possible cause It is possible that you have had a stroke.

          Medical help EMERGENCY! Dial 999/112 and ask for an ambulance.

      • Symptoms no longer present
    • Difficulty in speaking

      Are any of your symptoms still present?

      • Symptoms present
        • Possible cause It is possible that you have had a stroke.

          Medical help EMERGENCY! Dial 999/112 and ask for an ambulance.

      • Symptoms no longer present
    • None of the above

      Have you noticed any of the following?

      • Bloodstained vomit
        • Possible cause You may have bleeding in the digestive tract, perhaps from a peptic ulcer.

          Medical help EMERGENCY! Dial 999/112 and ask for an ambulance.

      • Red blood in the faeces
        • Possible cause You may have bleeding in the digestive tract, perhaps from a peptic ulcer.

          Medical help EMERGENCY! Dial 999/112 and ask for an ambulance.

      • Black, tarry faeces
        • Possible cause You may have bleeding in the digestive tract, perhaps from a peptic ulcer.

          Medical help EMERGENCY! Dial 999/112 and ask for an ambulance.

      • None of the above

        Did any of the following occur when you passed out?

        • You twitched uncontrollably
          • Possible cause You may have had a seizure, which could be due to epilepsy.

            Medical help EMERGENCY! Dial 999/112 and ask for an ambulance.

        • You bit your tongue
          • Possible cause You may have had a seizure, which could be due to epilepsy.

            Medical help EMERGENCY! Dial 999/112 and ask for an ambulance.

        • You passed urine
          • Possible cause You may have had a seizure, which could be due to epilepsy.

            Medical help EMERGENCY! Dial 999/112 and ask for an ambulance.

        • None of the above

          Did you feel faint or pass out immediately after either of the following?

          • Getting up suddenly
            • Possible cause The most likely explanation is a temporary drop in blood pressure due to a change in position; it is usually not a cause for concern (see Hypotension).

              Medical help See your doctor within 24 hours if you passed out. Make an appointment to see your doctor in the next few days even if you did not pass out.

          • Emotional shock
            • Possible cause Sudden psychological shock can result in feeling faint or passing out.

              Self-help Rest and ask someone to stay with you until you feel better. If it happens again, make an appointment to see your doctor.

          • Neither

            Does either of the following apply?

            • You have diabetes
              • Possible cause Low blood sugar levels are a possible cause of feeling faint or passing out, often with sweating, anxiety, and nausea (see Diabetes mellitus, and Hypoglycaemia).

                Medical help URGENT! Phone your doctor immediately! Eat or drink something sweet.

            • You had not eaten for several hours before passing out
              • Possible cause Low blood sugar levels are a possible cause of feeling faint or passing out, often with sweating, anxiety, and nausea (see Diabetes mellitus, and Hypoglycaemia).

                Medical help URGENT! Phone your doctor immediately! Eat or drink something sweet.

            • Neither

              Do you have any of the following symptoms?

              • Shortness of breath
                • Possible cause Anaemia is a possible cause of your symptoms.

                  Medical help See your doctor within 24 hours.

              • Paler skin than normal
                • Possible cause Anaemia is a possible cause of your symptoms.

                  Medical help See your doctor within 24 hours.

              • Undue tiredness
                • Possible cause Anaemia is a possible cause of your symptoms.

                  Medical help See your doctor within 24 hours.

              • None of the above

                Does either of the following apply?

                • You have had chest pain or you have a heart condition
                  • Possible causes You may have low blood pressure (see Hypotension) due to worsening of a pre-existing heart condition or an irregular heartbeat (see Arrhythmias).

                    Medical help URGENT! Phone your doctor immediately!

                • You have had palpitations
                  • Possible causes You may have low blood pressure (see Hypotension) due to worsening of a pre-existing heart condition or an irregular heartbeat (see Arrhythmias).

                    Medical help URGENT! Phone your doctor immediately!

                • Neither

                  Might you be pregnant?

                  • Possibly pregnant
                    • Possible cause Changes in blood flow during pregnancy can cause faintness.

                      Medical help Make an appointment to see your doctor.

                  • Not pregnant
                    • If you cannot identify a possible cause for passing out from this chart, phone your doctor immediately. If you cannot identify a possible cause for feeling faint, see your doctor within 24 hours.

Warning

Unconsciousness

If someone remains unconscious for more than a minute or so, whatever the suspected cause, you should get emergency medical help. If you need to leave the person to call for help, first lay him or her in the recovery position. Do not move the person if you suspect spinal injury.

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

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