Medical information for patients

Diarrhoea and Vomiting

Diarrhoea and vomiting often appear together, but may appear separately. Most times, although you feel terrible, there is little that a doctor can do for you, other than give advice similar to that below. For most intents and purposes the approach to the treatment is similar:


  • Only drink clear fluids, for example purpose-made electrolyte solutions or lemonade.
  • Start by just taking sips of fluid, and when the sickness subsides slowly build up the quantity.
  • You may take anti-diarrhoea medications which can help the symptoms, but they do not cure you any quicker.

Do not

  • Do not eat until at least 24 hours after the last sickness or diarrhoea subsides.
  • Do not drink milk, or drinks containing particles, as these take more digestion and irritate the bowel.
  • Do not take any tablets for headache or fever until the vomiting subsides.


Diarrhoea involves frequent and loose motions. It is usually caused by inflammation of the large intestine, which is where the body removes most of the fluid from digested food. The major cause, in the context that we are referring to, is infection, but there are various other rarer causes which occasionally occur. If diarrhoea persists and is not subsiding after a week, you should consult your doctor. If you have just got back form abroad and have diarrhoea it is wise to contact your doctor. Also it may be that you think it is due to a treatment you are taking from your doctor or dentist, and it is wise to consult your doctor immediately if this is the case.

In some cases bleeding occurs and this also should prompt a consultation with your doctor, but, as long as the blood loss is not heavy, this can await a daytime consultation.

In some cases a fever (high temperature) occurs with the diarrhoea. Initial first aid approaches to this involve fluid replacement, with electrolyte solution or soda pop (such as lemonade) and sponging down with tepid water. Paracetamol may be tolerated, but might possibly irritate the bowel more. If fever is excessive, or there are other causes for concern, consult with a doctor.


Vomiting, in this context, usually implies inflammation of the stomach, associated with an infection. Most commonly this is viral in origin and passed on like colds and influenza, but occasionally it may be due to contaminated food. Other causes of vomiting do exist, and persistent vomiting, lasting more than a few hours, or associated with constipation, high fever, abdominal pain or blood (which may look like coffee grounds when partially digested by acid) in the vomit should cause you to contact a doctor soon (even out of hours).

The main emphasis is on avoiding dehydration while avoiding gastric irritation. Thus, you should take clear fluids, preferably at a strength equivalent to body fluids (isotonic), and containing a similar balance of electrolytes (sodium and potassium) as well as an energy source (glucose). One of the most palatable options is simple lemonade, but there are proprietary brands of electrolyte solution, which come as sachets of powder or effervescent tablets and simply need to be added to water. To begin with this should be taken as the occasional sip, and slowly built up as the vomiting subsides. (Usually, after the stomach is empty, it only attempts to vomit a further three or four times.)

Frequent vomiting may cause a strain inside the lining of the stomach or oesophagus, leading to bleeding beginning after a few vomits. If this happens you should call a doctor.

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