Acute diarrhea is a common condition that affects both children and adults. It commonly presents with a sudden onset of loose or watery stools that come many times a day and may associated with abdominal cramps, fever and vomiting.

Acute diarrhea is usually caused by a gastrointestinal infection, commonly a virus, but occasionally by bacteria or parasites. Non-infective conditions can also present with acute diarrhea. These include adverse effects of medication, hormonal problems and acute gastroenterological diseases.

Acute diarrhea is usually self-limited and resolves spontaneously or with simple treatment. Chronic diarrhea should be considered if symptoms persist for more than 2 weeks, especially if there are symptoms such as abdominal pain and weight loss. Causes of chronic diarrhea include conditions such as inflammatory bowel disease, food intolerances, irritable bowel syndrome and pancreatic disease.

Viruses are the most common cause of acute infective diarrhea. You can suspect this if symptoms are mild, and the stools watery and non-bloody. Possible causes include Rotavirus in children and Norovirus in adults. The mode of transmission is fecal-oral, and most people get infected by ingesting contaminated food or beverages. Avoid consuming raw, partially cooked or unhygienically prepared foods, especially when you are travelling overseas. Wash your hands with soap and water before meals. Alcohol based hand sanitisers may not always kill viruses. Fruit juices and bottled drinks may seem safe but check that the ice that is served with it comes from a reliable source.

Bloody diarrhea is more alarming and is a sign of bowel inflammation. This is usually caused by bacteria such as Salmonella, Shigella, Campylobacter, and Escherichia coli, or occasionally by parasites such as Amoeba and Giardia. The latter occurs in people who go camping and ingest untreated water from rivers and lakes.

Acute diarrhea can usually be self-treated with a few simple steps. Rehydrate yourself to replace the water lost from the gut. Oral rehydration is best, and you should take fluids containing water, salts and sugars. An oral rehydration solution (ORS) with a mixture of salt, glucose and water is commercially available, or you can also take a combination of sports drinks, diluted fruit juices and soft drinks together with salted crackers and soups.

You can continue to eat as early re- feeding has been shown to decrease intestinal permeability and improve outcomes. Noodles, rice, cereals, bananas, soup, and boiled vegetables are the recommended choices.

Anti-diarrheal medication can be useful and many types are available over-the- counter in the pharmacy. Loperamide slows down the gut and reduces stool frequency. It works best when combined with simethicone to relieve gas-related discomfort. Intestinal adsorbents include drugs like smecta, kaolin or activated charcoal. Probiotics are also effective and they help to reduce the severity and duration of illness.

Antibiotic use is not necessary for most adults with mild, watery diarrhea. You should see a doctor to consider this when a bacterial diarrhea is suspected, or if your symptoms are severe, and associated with bloody stools and dehydration.

You should also seek medical attention early if the patient is a young child,
an elderly person or someone with multiple medical problems. Such patients may require hospitalisation for intravenous rehydration and further investigations such as stool tests. Colonoscopy is occasionally required to exclude more serious conditions such as colitis.