Acute gastroenteritis (AGE) is inflammation in the lining of the digestive tract. It results in diarrhea, stomach pain, nausea, and vomiting that can last up to 14 days.^[1]

Diarrhea, vomiting, and abdominal cramps are common symptoms of AGE. Fever is present in some cases. Monitoring for signs of severe disease is important in high risk populations, such as pregnant people, older people, babies, and people with health conditions that weaken the immune system. Signs of severe disease include:

• Six or more loose stools in one day
• Vomiting frequently for more than 24 hours
• Severe abdominal pain
• Bloody or black stools
• Any change in mental state, such as confusion
• Signs of dehydration Fever is a concerning symptom in small children, and a feverish child should always be assessed by a doctor.^[1]

AGE is usually a clinical diagnosis, based on the symptoms and a physical examination. A stool sample may be used to check for infection or blood.^[1]

AGE does not always require medical treatment. A few days of rest and taking in plenty of fluids and electrolytes may be enough. In most cases, the symptoms will resolve within 48 hours. Symptoms can be treated using over-the-counter (OTC) medications for stomach cramps, nausea, and pain. Loperamide is an OTC medication that can be taken to help bind stool, but it is not safe for small children.^[2] In severe cases, dehydration can be treated in the hospital with intravenous fluids and medications to help with vomiting. Depending on the cause, antibiotics may be prescribed, particularly for people at high risk of severe disease or who have traveler’s gastroenteritis. Antibiotics such as levofloxacin or azithromycin may be used based on stool sample testing or on history and examination findings.^[3] A vaccine for rotavirus, one of the most common causes of viral gastroenteritis, is given as part of the immunization schedule in many countries. People who receive this vaccine in childhood are less likely to develop severe symptoms of AGE.PMID 21501433

Zinc has been widely used to reduce the duration of diarrhea in AGE, especially for children. While it is recommended as a supplement in AGE, it seems to be most useful in lower income areas where nutritional deficiencies are more common. Smectite is a type of clay mineral that binds loose stools. Using smectite alongside zinc supplementation can shorten the duration of symptoms.^[4]

Probiotics are often recommended in the case of AGE, although exact strains and dosages are still unclear. Saccharomyces boulardii, a type of probiotic yeast, might be more useful for shortening the duration of diarrhea than other strains, especially if taken with zinc.^{[4] [5]}

Diet can play an important role in recovering from AGE. Historically, the BRAT diet was often recommended, which included only bananas, rice, applesauce, and toast, but this diet has fallen out of favor. People with AGE are now recommended to eat as close to their regular diet as possible. This is true for all ages, including breastfeeding or formula for infants. Undereating during the acute phase of AGE is common because of the symptoms, and returning to a high nutrient intake diet as soon as possible is a good way to aid recovery. This is especially important for babies and young children because periods of undereating can influence growth and development.^[2]

Ginger can be used for nausea, and seems to lessen the number of vomiting episodes experienced during AGE. Ginger is considered safe for children.^[6]

Some other alternative treatments, like apple cider vinegar, curcumin, and cinnamon have been suggested in the context of AGE, but there is currently not enough evidence to support their use.

AGE is most often caused by viral infections, most commonly norovirus and rotavirus. Other infectious causes, like bacterial or parasitic infections, are less common but can be more severe. AGE spreads from person to person, or through contaminated water or food. ^[1] Other less common causes include chemical ingestion and drug-induced AGE. Medications such as antibiotics and chemotherapy drugs can cause AGE. Accidental ingestion of chemicals like lead, certain types of mushrooms, or contaminated seafood can also cause AGE. ^[7]