Rehydrating for Dehydration From Diarrhea

Diarrhea is the passage of three or more loose or watery stools per day. It often is caused by an infection of the intestines, known as gastroenteritis, or the “stomach flu.” When a person loses excess water from diarrhea, a complication called dehydration may occur.

Dehydration symptoms range in severity from feeling thirsty and tired to fainting or becoming confused. While anyone can develop dehydration from diarrhea, certain people are at a higher risk, namely babies, young children, and older adults.

Dehydration is treated by restoring the body’s water content. Depending on the severity, this is accomplished by drinking oral rehydration solutions or receiving fluids intravenously (IV, within the veins) in a medical facility.

Symptoms of Dehydration From Diarrhea

Dehydration from diarrhea is caused by excess water loss within the body and, sometimes, inadequate fluid intake by the person experiencing the diarrhea. Symptoms of dehydration, whether caused by diarrhea or another cause, include the following.

Emergency Symptoms

Dehydration from diarrhea can be severe and, in extreme cases, life-threatening.

Seek immediate medical attention for any of the following symptoms:

• Breathing fast or experiencing a fast heartbeat
• Confusion
• Light-headedness or fainting
• Not urinating
• Rapid weight loss (over 10% of body weight)

Seek care right away for any of the following signs and symptoms in a baby or young child:

• Bluish-purple or mottled skin color
• Decreased alertness, being less active, and appearing drowsy
• Dry mouth and tongue
• Fast and weak heartbeat
• Few to no tears in babies when crying
• Marked decrease or absence of urination (minimal wet diapers in babies)
• Rapid breathing
• Sunken eyes or sunken soft spot on the baby’s head
• Wrinkled skin

Mild to Moderate Symptoms

Symptoms of mild-to-moderate dehydration in adults may include:

• Constipation or hard stools
• Darkening of urine and decrease in urination
• Dry lips and tongue
• Fatigue or feeling sluggish
• Feeling thirsty
• Headache
• Lack of focus
• Muscle weakness or cramps

Symptoms of mild dehydration in babies or young children may include:

• Increased thirst
• Normal or mildly reduced urine production
• Tacky or slightly dry mouth

Why Diarrhea Leads to Dehydration

It’s best to review the basic steps of normal digestion to understand how diarrhea can lead to dehydration.

These steps include:

• After eating, food travels from a person’s mouth down their esophagus (food pipe) and into their stomach.
• Within the stomach, the food is churned in an acidic fluid and partially digested contents before being emptied into the small intestines.
• The walls of the small intestines absorb water and nutrients into the bloodstream.
• The remaining waste travels to the large intestines (colon), where more water is absorbed, turning the liquid waste into stool.

In cases of diarrhea, bowel movements have an increased water content for one or both of the following reasons:

• The small intestines do not adequately absorb water.
• The large intestines actively release water.

Disturbances in electrolytes (charged minerals that maintain fluid balance within the body) can also occur in dehydration, namely the loss of potassium (hypokalemia).

Hypokalemia may manifest with severe dehydration because water loss triggers the release of aldosterone—a hormone made by the adrenal glands. Aldosterone signals the release of potassium from the kidneys via urine and the colon via stool.

Depending on the cause and severity of the diarrhea, other electrolyte disturbances can occur, including a decrease in bicarbonate and an increase in sodium.

Young children, especially babiesare particularly vulnerable to developing dehydration from diarrhea because they have a greater body surface area compared to adults. This higher ratio increases their environmental exposure, making them more prone to water losses.

Young children are also vulnerable to diarrhea-related dehydration because they may be unable to communicate their need for water or independently obtain water.

Older adults are another population vulnerable to dehydration from diarrhea for these age-related reasons:

• They have a decreased thirst reflex.
• Their kidney function naturally declines, hindering their ability to hold onto water.
• Their total body water content is lower due to reduced muscle mass.

Older adults are also more likely to have chronic health conditions that pose various obstacles to ensuring proper hydration. For example, increasing age is the strongest risk factor for dementia (an umbrella term for brain disorders associated with impaired cognitive function).

Dementia can increase the risk of dehydration from:

• Difficulties communicating thirst to loved ones or caregivers
• Forgetting or lack of interest in drinking fluids
• Related problems like difficulty swallowing or reduced sense of taste

Lastly, individuals with certain medical conditions that cause them to urinate a lot—for example, those with diabetes—or those taking medications like diuretics (drugs that remove excess water and salt from the body) are also at an increased risk for dehydration.

Treatments to Rehydrate

There are two ways to rehydrate from diarrhea:

Oral rehydration solutions are generally sufficient for mild and some moderate cases of dehydration. They contain a specific proportion of fluid, sugar, and electrolytes to replace water and are available in most grocery stores and pharmacies without a prescription.

Examples of oral rehydration solutions include:

• CeraLyte
• Enfalyte
• Pedialyte
• Rehydralyte

Severe dehydration from diarrhea requires IV fluids in a medical or hospital setting. Fluids are often given rapidly at first and then slowly.

People at higher risk for dehydration, such as babies, young children, and older adults, may require IV fluids, even if their dehydration is mild.

Timeline of Symptom Duration

The timeline of diarrhea-related dehydration depends on the underlying cause and its severity.

For example, a virus causes most cases of diarrhea, which lasts a day or two, although some may last up to 10 days.

If dehydration occurs with a diarrhea, rehydration can often be completed within a few hours, whether at home with an oral rehydration solution or in the hospital receiving IV fluids.

After rehydration, drinking fluids like water and eating can begin.

Secondary Complications

Dehydration, especially when prolonged, increases an adult’s chances of developing the following conditions:

It also increases the risk of hospitalization and death, namely in older adults.

Research suggests that mild dehydration can impair cognitive performance in children. Severe dehydration in children can lead to acute kidney injury, which is fortunately usually reversible with fluids.

With severe dehydration, potentially life-threatening complications can occur to anyone. They include:

• Hypernatremia refers to elevated sodium levels in the bloodstream. Symptoms begin with listlessness, irritability, and muscle weakness and may evolve, if not treated, to muscle twitching, seizures, and coma.
• Hypovolemic shock is when blood pressure drops so low from excess water loss that it hinders oxygen delivery to organs like the brain, heart, and kidney.

How to Stay Ahead of Dehydration From Diarrhea

Follow these tips to remain hydrated with diarrhea:

• When diarrhea starts, drink clear fluids like water, plain tea, or broth.
• Talk with a provider about drinking an oral rehydration solution to prevent dehydration.
• Avoid caffeinated drinks or sugary drinks, which can worsen diarrhea and the risk of dehydration.
• If diarrhea accompanies vomiting or stomach cramps, take small sips of fluid every few minutes.

Summary

Dehydration occurs when you lose more water than you take in. It’s a common complication of diarrhea, which is the passage of three or more loose or watery stools per day. Diarrhea can cause dehydration in anyone, although babies, young children, and older adults are at an increased risk.

Symptoms of diarrhea-related dehydration can range from mild (e.g., increased thirst or headache) to severe (e.g., fainting or confusion). Diarrhea can also lead to life-threatening complications, including shock and dangerous electrolyte imbalances.

Rehydration, or restoration of the body’s water content, is the treatment for dehydration and can often be completed within a few hours. Mild (and some moderate) dehydration cases are usually treated at home by drinking an oral rehydration solution, whereas severe cases require IV fluids at a medical facility.