Drinking saltwater can cause diarrhea. When water with a high salt concentration, like ocean water, is ingested, the body’s digestive system reacts to this imbalance. This response attempts to regulate salt levels, often leading to fluid shifts within the body.
The Osmotic Effect of Salt Water
The primary reason saltwater ingestion leads to diarrhea is osmosis. This process involves water moving across a semi-permeable membrane from a lower to a higher solute concentration. When highly saline water enters the intestines, the salt concentration outside the digestive tract cells becomes much higher than inside.
To equalize this difference, water is drawn from the body’s cells into the intestinal lumen. This influx increases fluid volume in the intestines, which the body expels as loose, watery stools, known as osmotic diarrhea. This process also causes the body to lose water, leading to dehydration and making electrolyte balance difficult.
Other Factors from Salt Water Exposure
Beyond osmosis, saltwater exposure can cause diarrhea through other mechanisms. Oceans and lakes often contain various microorganisms including bacteria, viruses, and parasites. These contaminants can originate from sources like animal feces, sewage runoff, or agricultural runoff.
Ingesting contaminated water can cause gastrointestinal infections. Symptoms typically include diarrhea, vomiting, and abdominal pain. Specific bacteria like E. coli and Vibrio vulnificus are known causes of illness from contaminated water exposure. Chemical pollutants from industrial discharges or storm water may also contribute to digestive issues. Additionally, swallowing excessive amounts of water, regardless of its salinity or microbial content, can irritate the digestive system and result in loose stools.
When to Seek Medical Attention
While mild diarrhea from saltwater exposure might resolve on its own, certain symptoms warrant medical attention. Seek care if signs of severe dehydration develop, such as reduced urination, intense thirst, dry mouth, dizziness, fatigue, or sunken eyes. Other concerning indicators include persistent vomiting, a high fever, or severe abdominal pain.
Prompt medical evaluation is needed for blood, black discoloration, or pus in the stools. If diarrhea lasts for more than a few days, particularly beyond 48 hours in adults or 24 hours in children, consult a healthcare provider. Vulnerable individuals, including young children, the elderly, or those with weakened immune systems, should seek medical help more readily due to their increased risk of complications from dehydration. In the meantime, rehydration with plain water or oral rehydration solutions (ORS), which contain specific amounts of sugar and salts, can help replace lost fluids and electrolytes.