As diarrhea can be hard to define in each person a good definition is "an abnormal increase in the frequency and liquidity of the stools." This software only deals with acute, sudden onset diarrhea, as opposed to those with long-term problems. If there is a long-term problem please do not use this software – seek medical advice!.

Most types of diarrhea are harmless and will go away by themselves within hours to days. As long as the sufferer doesn’t get dehydrated, there’s little to worry about. There are two exceptions, though; bacterial infection and giardiasis.

- Bacterial infection. Salmonella, campylobacter, and e. coli are the most common types of bacterial infection causing diarrhea. There serious conditions need immediate physician evaluation for proper treatment.
- Giardiasis. This parasite usually infects young children, usually in day care settings where it is passed child to child by direct contact, and by adults changing different children’s diapers without hand washing in between. Family members of affected children are also at risk. Giardiasis can last months or longer without treatment, and spread rapidly. Finding the source and testing or treating all contacts is important, since some people carry and spread the infection without having diarrhea themselves.

You usually catch infectious types of diarrhea by actually eating microscopic viruses, bacteria, or parasites. These microbes then flourish in your intestines, causing damage and diarrhea. Prevention is a matter of good hygiene. Always wash your hands before preparing your own food or for others.

- Keep your hands away from your hands and mouth in general.
- Wash after shaking hands with a number of people.
- Of course, always wash your hands after using the bathroom, and be wary of those who don’t!

Trying to figure out the cause of non-infectious diarrhea can be difficult. If there’s an obvious relationship between diarrhea and cramping and the ingestion of dairy products a few hours earlier, then lactose intolerance is a very likely diagnosis. If your problems are predictably aggravated by stressful situations or other emotional or situational events, then Irritable Bowel Syndrome is a more likely definition – and professional help will be required.