Acute Diarrhea: Causes, Symptoms & Treatment

Key takeaways:

• Most cases of diarrhea are benign and will go away on their own.
• See a doctor if you are running a fever or having bloody diarrhea.
• Dehydration can be a complication of untreated diarrhea.

Diarrhea is common for adults and children. Diarrhea is passing loose or watery stools at least three times daily. Often it’s mild and resolves in 12-24 hours. Sometimes diarrhea indicates a more serious medical problem. Diarrhea can lead to dehydration. This is especially true in children and elderly patients.

Definition of acute diarrhea

Diarrhea is first classified as either acute or chronic. Diarrhea is acute if lasting less than 14 days and chronic if lasting four weeks or longer.

Symptoms of acute diarrhea

Watery stool three times a day or more is the definition of acute diarrhea. It can be accompanied by blood or mucus in the stool.

Loose, watery stool

This may be the only symptom you experience. It may be that you are passing frequent but normal stools. This would not be classified as diarrhea but as pseudo-diarrhea or hyperdefecation.

Blood in the stool

Blood in the stool presents as bright red blood (hematochezia) or dark tarry-black stools (melena). This is a sign of either more serious infection or inflammatory bowel conditions. Be sure to mention this to your doctor if you think it is present.

Mucus in the stool

While small amounts of mucus in the stool can be normal, this is normally not visible to the naked eye. It can mean either an infectious or inflammatory cause of diarrhea.

Causes of acute diarrhea

Acute diarrhea is further classified into watery or invasive diarrhea based on the symptoms and their causes.

Watery diarrhea

Watery (or non-inflammatory) diarrhea is frequent loose stools without blood or mucus. There can be other symptoms, such as abdominal pain or nausea and vomiting. This is usually due to viral infection.

Invasive diarrhea

Invasive (or inflammatory) diarrhea is acute diarrhea accompanied by bloody stools. It may be accompanied by fever and abdominal pain. It is usually due to bacterial infection of the intestines.

Health risks associated with acute diarrhea

Diarrhea is usually temporary and will resolve on its own. It can cause dehydration and other complications if it’s severe or prolonged.

Dehydration

Dehydration is a common complication of diarrhea more commonly affecting children and the elderly. Be sure to watch closely for the signs and symptoms of dehydration. These include dizziness, dry skin, cracked lips, dark urine, and muscle cramps.

Other complications

Infectious or inflammatory causes of diarrhea can cause serious complications. One such complication is toxic megacolon. This rare but deadly complication occurs as a result of prolonged infection or inflammation of the colon. Symptoms include abdominal distension (bloating) and severe pain. This is an emergency and you should go to the emergency room if you suspect this is present.

Treating acute diarrhea at home

Frequently, treatment for diarrhea can be safely initiated at home.

Rehydration

Rehydration is one of the mainstays of treatment for diarrhea. The best way to rehydrate is to drink an oral rehydration solution or a low-sugar sports drink. There are oral rehydration packets you can purchase at your local pharmacy. You can make a rehydration solution at home if you’d prefer.

Diet

As soon as you feel able, try introducing bland foods into your diet. Eating and digesting food helps your intestines heal from illnesses and provides needed electrolytes and minerals lost by diarrhea. Avoid spicy or greasy foods and go slowly, eating small frequent snacks rather than large meals.

Over-the-counter medication

Several potential over-the-counter therapies can help your symptoms. Probiotics restore normal intestinal bacteria destroyed by diarrhea. These can reduce the length of your illness.

Anti-diarrheal agents are also useful for your symptoms. But please speak to your doctor before starting these medications. These can make some infections worse and cause serious complications.

When you should see a doctor about acute diarrhea

Many times diarrhea is limited and will not cause complications. However, some situations should prompt a visit to a doctor’s office.

You should see a doctor if:

• The diarrhea lasts longer than 48 hours.
• The symptoms are so severe you cannot complete normal daily tasks.
• You have a fever (temperature greater than 100.4 degrees Fahrenheit).
• You notice bloody or dark-black (tarry) stools.
• There are signs of dehydration.
• If you have recently taken antibiotics and now have diarrhea.

You should go to the emergency room if:

• You are experiencing severe abdominal pain.
• You have not made any urine for 6 hours.
• The patient is confused or having difficulty staying awake.

Questions to ask your doctor about acute diarrhea

• What do you think is causing this diarrhea?
• Can I take over-the-counter medications for the symptoms?
• How long do you expect this to last?
• When should I call you back if I don’t think I’m improving?

How a doctor can help treat acute diarrhea

Depending on the cause of your diarrhea, your doctor may prescribe some, all, or none of these treatments. It varies from patient to patient.

IV rehydration

If you can't take oral fluids or your dehydration is severe, your doctor may recommend rehydration through an IV (intravenous catheter). This is when fluids are delivered directly into your veins and it is a more rapid rehydration method. This is performed in an office or urgent/emergent care setting.

Antibiotics

Some scenarios call for therapy with antibiotics. Your doctor will discuss this with you, as not all diarrheal illnesses require antibiotics. It’s important to take your course exactly as prescribed. Don’t stop early, even if you feel better.

Specialist referral

Your doctor may want you to see a specialist for your diarrhea. This kind of doctor is a gastroenterologist. They will take another history, examine you, and perhaps repeat or perform new lab work and studies. You may need an x-ray, CT scan, or even a colonoscopy to determine the cause of your symptoms.

How to prevent acute diarrhea

Preventing the spread of diarrhea is important. There are several steps you can take to minimize spreading it.

Handwashing

Everyone in your household should regularly wash their hands with soap and water. This reduces the risk of spreading not only the agent that causes diarrhea but also other bacteria present in the stool. It is important to wash your hands after defecating (pooping), after wiping the patient’s behind or handling a dirty diaper, before preparing food, and before eating.

Food safety

Careful food safety practices are another component of preventing diarrheal illness. These include not eating raw food, cooking food until it is hot throughout and eating it immediately after, washing your dishes and utensils with soap and water, and keeping your clean food and utensils away from dirty dishes.

Vaccination

There are safe and effective vaccines for certain diarrheal illnesses. In the United States, vaccinating children against rotavirus, a common cause of diarrhea, is recommended.

Managing acute diarrhea

Diarrhea is a common experience for adults and children alike. Many times it will resolve after 24-48 hours without serious complications. If you are unsure whether or not to be seen, go ahead and call your doctor and ask.

General Medicine follows a strict editorial process, including using real experts to write our articles, vetted primary sources, fact-checking, a secondary medical review, and updates as necessary. This article was medically reviewed and fact checked by Dr. Lane Thaut, DO.

Sources

Guerrant, Richard L., et al. "Practice guidelines for the management of infectious diarrhea." Clinical infectious diseases 32.3 (2001): 331-351.

Nemeth, Valerie, and Nicholas Pfleghaar. “Diarrhea.” PubMed, StatPearls Publishing, 21 Nov. 2022, www.ncbi.nlm.nih.gov/books/NBK448082/.

Rao, C. Durga, P. P. Maiya, and M. Ananda Babu. "Non-diarrhoeal increased frequency of bowel movements (IFoBM-ND): enterovirus association with the symptoms in children." BMJ Open Gastroenterology 1.1 (2014): e000011.

Akhondi, Hossein, and Kari A. Simonsen. “Bacterial Diarrhea.” PubMed, StatPearls Publishing, 2020, www.ncbi.nlm.nih.gov/books/NBK551643/.

Barr, Wendy, and Andrew Smith. "Acute diarrhea in adults." American family physician 89.3 (2014): 180-189.

Descoteaux-Friday, Garrett J., and Isha Shrimanker. “Chronic Diarrhea.” PubMed, StatPearls Publishing, 7 Aug. 2023, www.ncbi.nlm.nih.gov/books/NBK544337/.

Ewelina Skomorochow, and Jose Pico. “Toxic Megacolon.” Nih.gov, StatPearls Publishing, 15 Nov. 2019, www.ncbi.nlm.nih.gov/books/NBK547679/.

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Homemade Oral Rehydration Solutions Base Beverage Recipe. https://med.virginia.edu/ginutrition/wp-content/uploads/sites/199/2023/12/Homemade-Oral-Rehydration-Solutions-11-2023.pdf

Allen, Stephen J., et al. "Probiotics for treating acute infectious diarrhoea." Cochrane Database of Systematic Reviews 11 (2010).

“The Treatment of Diarrhoea.” Www.who.int, www.who.int/publications/i/item/9241593180.

‌CDC. “Child and Adolescent Immunization Schedule by Age (Addendum Updated June 27, 2024).” Vaccines & Immunizations, 27 June 2024, www.cdc.gov/vaccines/hcp/imz-schedules/child-adolescent-age.html.