Fever

For children under 12, see chart 45

Normal temperature varies from one person to another, but if your temperature is 38°C (100.4°F) or above, you have a fever. Most fevers are due to infection, but heat exposure or certain drugs can also raise body temperature. In all cases, follow the self-help advice for bringing down a fever.

  • Do you have a rash?

    • Rash
    • No rash

      Do you have a headache?

      • Severe headache

        Do you have any of the following symptoms?

        • Drowsiness or confusion
          • Possible cause There is a possibility that you have meningitis.

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

        • Dislike of bright light
          • Possible cause There is a possibility that you have meningitis.

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

        • Neck pain on bending the head forwards
          • Possible cause There is a possibility that you have meningitis.

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

        • None of the above

          Do you have a cough?

          • Cough

            Are you having problems breathing?

            • You are short of breath
              • Possible cause A chest infection, such as pneumonia, is a possible cause.

                Medical help URGENT! Phone your doctor immediately!

            • Breathing is painful
              • Possible cause A chest infection, such as pneumonia, is a possible cause.

                Medical help URGENT! Phone your doctor immediately!

            • Breathing is normal

              Have you been coughing up sputum?

              • Sputum
                • Possible causes A chest infection, such as acute bronchitis, may cause your symptoms. Tuberculosis is also a possibility.

                  Medical help See your doctor within 24 hours.

              • No sputum

                Do you have either of the following symptoms?

                • Generalized aches and pains
                  • Possible cause A viral illness, such as a severe cold (see Common cold) or influenza, is the most probable cause of your symptoms.

                    Self-help Follow the self-help advice for bringing down a fever. Consult your doctor if your symptoms worsen, if you are no better in 2 days, or if other symptoms develop.

                • Runny nose
                  • Possible cause A viral illness, such as a severe cold (see Common cold) or influenza, is the most probable cause of your symptoms.

                    Self-help Follow the self-help advice for bringing down a fever. Consult your doctor if your symptoms worsen, if you are no better in 2 days, or if other symptoms develop.

                • Neither

                  Do you have any urinary problems?

                  • Pain on passing urine
                    • Possible causes Cystitis is the most likely cause of your symptoms, but pyelonephritis is also possible, especially if you have back pain.

                      Medical help See your doctor within 24 hours.

                  • Passing urine too frequently
                    • Possible causes Cystitis is the most likely cause of your symptoms, but pyelonephritis is also possible, especially if you have back pain.

                      Medical help See your doctor within 24 hours.

                  • Neither

                    Do you have a sore throat?

                    • Sore throat
                    • No sore throat

                      Have you had several bouts of fever over the past few weeks?

                      • Recurrent fever
                      • No other recent fever
                        • If you cannot identify a possible cause for your fever from this chart, see your doctor within 24 hours.

          • No cough

            Do you have any urinary problems?

            • Pain on passing urine
              • Possible causes Cystitis is the most likely cause of your symptoms, but pyelonephritis is also possible, especially if you have back pain.

                Medical help See your doctor within 24 hours.

            • Passing urine too frequently
              • Possible causes Cystitis is the most likely cause of your symptoms, but pyelonephritis is also possible, especially if you have back pain.

                Medical help See your doctor within 24 hours.

            • Neither

              Do you have a sore throat?

              • Sore throat
              • No sore throat

                Have you had several bouts of fever over the past few weeks?

                • Recurrent fever
                • No other recent fever
                  • If you cannot identify a possible cause for your fever from this chart, see your doctor within 24 hours.

      • Mild headache

        Do you have a cough?

        • Cough

          Are you having problems breathing?

          • You are short of breath
            • Possible cause A chest infection, such as pneumonia, is a possible cause.

              Medical help URGENT! Phone your doctor immediately!

          • Breathing is painful
            • Possible cause A chest infection, such as pneumonia, is a possible cause.

              Medical help URGENT! Phone your doctor immediately!

          • Breathing is normal

            Have you been coughing up sputum?

            • Sputum
              • Possible causes A chest infection, such as acute bronchitis, may cause your symptoms. Tuberculosis is also a possibility.

                Medical help See your doctor within 24 hours.

            • No sputum

              Do you have either of the following symptoms?

              • Generalized aches and pains
                • Possible cause A viral illness, such as a severe cold (see Common cold) or influenza, is the most probable cause of your symptoms.

                  Self-help Follow the self-help advice for bringing down a fever. Consult your doctor if your symptoms worsen, if you are no better in 2 days, or if other symptoms develop.

              • Runny nose
                • Possible cause A viral illness, such as a severe cold (see Common cold) or influenza, is the most probable cause of your symptoms.

                  Self-help Follow the self-help advice for bringing down a fever. Consult your doctor if your symptoms worsen, if you are no better in 2 days, or if other symptoms develop.

              • Neither

                Do you have any urinary problems?

                • Pain on passing urine
                  • Possible causes Cystitis is the most likely cause of your symptoms, but pyelonephritis is also possible, especially if you have back pain.

                    Medical help See your doctor within 24 hours.

                • Passing urine too frequently
                  • Possible causes Cystitis is the most likely cause of your symptoms, but pyelonephritis is also possible, especially if you have back pain.

                    Medical help See your doctor within 24 hours.

                • Neither

                  Do you have a sore throat?

                  • Sore throat
                  • No sore throat

                    Have you had several bouts of fever over the past few weeks?

                    • Recurrent fever
                    • No other recent fever
                      • If you cannot identify a possible cause for your fever from this chart, see your doctor within 24 hours.

        • No cough

          Do you have any urinary problems?

          • Pain on passing urine
            • Possible causes Cystitis is the most likely cause of your symptoms, but pyelonephritis is also possible, especially if you have back pain.

              Medical help See your doctor within 24 hours.

          • Passing urine too frequently
            • Possible causes Cystitis is the most likely cause of your symptoms, but pyelonephritis is also possible, especially if you have back pain.

              Medical help See your doctor within 24 hours.

          • Neither

            Do you have a sore throat?

            • Sore throat
            • No sore throat

              Have you had several bouts of fever over the past few weeks?

              • Recurrent fever
              • No other recent fever
                • If you cannot identify a possible cause for your fever from this chart, see your doctor within 24 hours.

      • No headache

        Do you have a cough?

        • Cough

          Are you having problems breathing?

          • You are short of breath
            • Possible cause A chest infection, such as pneumonia, is a possible cause.

              Medical help URGENT! Phone your doctor immediately!

          • Breathing is painful
            • Possible cause A chest infection, such as pneumonia, is a possible cause.

              Medical help URGENT! Phone your doctor immediately!

          • Breathing is normal

            Have you been coughing up sputum?

            • Sputum
              • Possible causes A chest infection, such as acute bronchitis, may cause your symptoms. Tuberculosis is also a possibility.

                Medical help See your doctor within 24 hours.

            • No sputum

              Do you have either of the following symptoms?

              • Generalized aches and pains
                • Possible cause A viral illness, such as a severe cold (see Common cold) or influenza, is the most probable cause of your symptoms.

                  Self-help Follow the self-help advice for bringing down a fever. Consult your doctor if your symptoms worsen, if you are no better in 2 days, or if other symptoms develop.

              • Runny nose
                • Possible cause A viral illness, such as a severe cold (see Common cold) or influenza, is the most probable cause of your symptoms.

                  Self-help Follow the self-help advice for bringing down a fever. Consult your doctor if your symptoms worsen, if you are no better in 2 days, or if other symptoms develop.

              • Neither

                Do you have any urinary problems?

                • Pain on passing urine
                  • Possible causes Cystitis is the most likely cause of your symptoms, but pyelonephritis is also possible, especially if you have back pain.

                    Medical help See your doctor within 24 hours.

                • Passing urine too frequently
                  • Possible causes Cystitis is the most likely cause of your symptoms, but pyelonephritis is also possible, especially if you have back pain.

                    Medical help See your doctor within 24 hours.

                • Neither

                  Do you have a sore throat?

                  • Sore throat
                  • No sore throat

                    Have you had several bouts of fever over the past few weeks?

                    • Recurrent fever
                    • No other recent fever
                      • If you cannot identify a possible cause for your fever from this chart, see your doctor within 24 hours.

        • No cough

          Do you have any urinary problems?

          • Pain on passing urine
            • Possible causes Cystitis is the most likely cause of your symptoms, but pyelonephritis is also possible, especially if you have back pain.

              Medical help See your doctor within 24 hours.

          • Passing urine too frequently
            • Possible causes Cystitis is the most likely cause of your symptoms, but pyelonephritis is also possible, especially if you have back pain.

              Medical help See your doctor within 24 hours.

          • Neither

            Do you have a sore throat?

            • Sore throat
            • No sore throat

              Have you had several bouts of fever over the past few weeks?

              • Recurrent fever
              • No other recent fever
                • If you cannot identify a possible cause for your fever from this chart, see your doctor within 24 hours.

Warning

High temperature

If you are feeling unwell, you should take your temperature every 4 hours. Call your doctor immediately if your temperature rises to 39°C (102°F) or above, and take steps to lower the fever without delay (see Bringing down a fever).

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

The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.

Back to top