Viral gastroenteritis, commonly known as the stomach flu, is an intestinal infection that causes inflammation, leading to symptoms like vomiting and diarrhea. These symptoms result in a rapid loss of both bodily fluids and electrolytes, which are salts and minerals necessary for nerve and muscle function. Maintaining proper hydration is the single most effective step in managing the illness and preventing severe dehydration. Replacing these lost components is the primary goal of care during a bout of the stomach flu.
Identifying Signs of Dehydration
Recognizing the signs of fluid loss is necessary to determine the proper course of action. A common initial indicator is a marked increase in thirst, as the body attempts to signal its fluid deficit. Reduced urination or urine that appears dark yellow or amber suggests the kidneys are conserving water due to low fluid volume.
Lethargy, fatigue, and dizziness can also accompany moderate dehydration. A dry mouth, cracked lips, and a sticky sensation in the mouth are physical indicators of decreased saliva production. These symptoms are often manageable at home by consistently replacing lost fluids and electrolytes.
However, certain signs point toward severe dehydration requiring immediate medical evaluation. These include light-headedness or fainting, sunken eyes or cheeks, and skin that does not flatten back to normal quickly after being pinched. An inability to keep any fluids down for 24 hours also signals a dangerous fluid imbalance.
Strategic Fluid Replacement: Choosing the Right Liquids
Effective hydration during gastroenteritis requires replacing water, sodium, and glucose lost through vomiting and diarrhea. Oral Rehydration Solutions (ORS) are specifically formulated for this purpose, containing precise amounts of water, sodium, potassium, and glucose. The combination of sodium and glucose maximizes fluid absorption in the small intestine by pulling water into the body.
Pure water alone is insufficient because it lacks necessary electrolytes, while sports drinks often contain too much sugar and not enough sodium. High sugar concentrations can actually worsen diarrhea by pulling more water into the intestinal tract. Commercial ORS products are superior because they follow the World Health Organization (WHO) guidelines for the ideal ratio of salts to sugar.
Clear broths can serve as a secondary source of sodium and fluid, and diluted fruit juices can offer some sugar and potassium, but these should be used cautiously. Liquids that should be avoided include full-strength fruit juices, sodas, and caffeinated beverages, as their high sugar content or diuretic properties can aggravate symptoms and increase fluid loss.
The Rehydration Process: Timing and Technique
The method of consuming fluids is just as important as the type of liquid chosen, especially when the stomach is irritated and prone to vomiting. After an episode of vomiting, the stomach needs a rest period, typically around two hours, before attempting to reintroduce liquids. Gulping liquids can stretch the stomach wall and trigger vomiting, negating the hydration effort.
The recommended approach is to use a “sip, wait, repeat” strategy, allowing the body to absorb small amounts gradually. Fluids should be consumed very frequently, such as every five to fifteen minutes. For adults, this means taking only one or two small sips or using a teaspoon to deliver the liquid.
If small amounts are tolerated for several hours, the volume can be slowly increased, though consumption should remain spaced out. Even with ongoing diarrhea, consistent, small-volume intake of an ORS helps the intestines absorb what they can and prevents dehydration from progressing.
When to Introduce Solids and Seek Medical Attention
Once vomiting has completely stopped for several hours and the patient is tolerating clear fluids, a slow return to solid foods can begin. The focus should be on bland, easy-to-digest, low-fiber foods that will not irritate the sensitive digestive lining. Examples include plain toast, bananas, rice, or applesauce, often referred to by the acronym BRAT.
These foods provide necessary calories and nutrients without requiring excessive work from the gastrointestinal tract, which may take up to a week to fully recover. It is beneficial to avoid high-fat, spicy, or heavily seasoned foods, as well as dairy products, which can be difficult to digest due to temporary lactose intolerance following the infection.
While most cases of stomach flu resolve with proper hydration, certain severe symptoms warrant immediate professional consultation. Seek medical attention if a person cannot keep down any fluids for 24 hours, or if there is blood in the stool or vomit. A persistent high fever above 102°F or severe abdominal pain are also warning signs that may indicate a more serious condition.