Understanding How do you fix dehydration in malnutrition? Safely and Effectively

October 18, 2025 •

4 min read

According to the World Health Organization, standard rehydration techniques used for well-nourished individuals can be hazardous for those with severe malnutrition due to altered fluid and electrolyte balance. Proper care requires a specialized and cautious approach to avoid fatal complications like fluid overload and refeeding syndrome.

Quick Summary

Correcting dehydration in malnutrition demands a specific protocol, often involving low-sodium solutions like ReSoMal and slow rehydration to prevent dangerous electrolyte shifts. Extreme caution is used with intravenous fluids, and close monitoring for complications, including refeeding syndrome, is essential. Medical supervision is required for a safe recovery.

Key Points

Use Specialized Solutions: Standard ORS is unsafe; use a specialized low-sodium, high-potassium solution like ReSoMal for rehydrating malnourished individuals.
Rehydrate Slowly: Give fluids slowly, orally or via a nasogastric tube, while frequently monitoring for signs of improvement or overhydration.
Limit Intravenous Fluids: Reserve IV rehydration for cases of severe shock only, as aggressive fluid administration carries a high risk of fluid overload.
Monitor for Refeeding Syndrome: Be aware of the signs of refeeding syndrome and monitor for dangerous electrolyte shifts, particularly in phosphorus, potassium, and magnesium.
Follow Cautious Feeding Protocols: After rehydration, initiate feeding gradually with appropriate formulas like F-75 to begin nutritional rehabilitation safely.
Ensure Electrolyte Monitoring: Regularly check electrolyte levels, as deficiencies may not be apparent until refeeding begins.

The Unique Challenges of Rehydrating Malnourished Patients

When a person is malnourished, their body undergoes significant physiological changes that alter how it handles fluids and electrolytes. This makes standard rehydration protocols dangerous. A severely malnourished individual often has a potassium deficiency and an excess of total body sodium, even if their blood sodium levels appear low. The body's weakened heart function, especially common in malnourished children, increases the risk of fluid overload and heart failure during rapid rehydration. Furthermore, the process of reintroducing nutrition can trigger refeeding syndrome, a potentially fatal metabolic disturbance.

Recognizing the Signs of Dehydration in Malnutrition

The typical signs of dehydration can be masked or complicated by a person's nutritional state. For example, sunken eyes may be a sign of dehydration or simply part of the severe weight loss associated with malnutrition. Signs to watch for include:

Extreme thirst
Lethargy or drowsiness
Passing urine less frequently than usual
Dark-colored, strong-smelling urine
Dry mouth, lips, and tongue
Sunken eyes
A sunken soft spot (fontanelle) on a baby's head
Dizziness or lightheadedness
Fatigue

Specialized Oral Rehydration

For malnourished individuals who are not in shock, a specialized oral rehydration solution (ORS) is the preferred method. The World Health Organization (WHO) recommends using ReSoMal, a solution with lower sodium and higher potassium content than standard ORS, specifically designed for malnourished patients.

Rehydration with ReSoMal (or equivalent) guidelines:

Slow Administration: Administer the solution slowly and steadily to avoid overwhelming the weakened system. For example, give 5 mL/kg every 30 minutes for the first two hours.
Monitor Closely: Watch for signs of improved hydration, but also for overhydration, such as increased respiratory or pulse rate. Monitoring should be frequent, especially in the initial hours.
Alternative Solution: If ReSoMal is unavailable, half-strength standard WHO low-osmolarity ORS with added potassium and glucose can be used.
Consider Nasogastric Tube: If the patient is too weak to drink, a nasogastric tube may be used for administration.


Feature	Standard WHO ORS	ReSoMal (ORS for Malnutrition)
Intended Use	Well-nourished individuals with acute diarrhea.	Severely malnourished patients with dehydration.
Sodium Content	Standard concentration (~75 mmol/L).	Lower concentration (~45 mmol/L), suited for patients with excess total body sodium.
Potassium Content	Lower concentration.	Higher concentration (~40 mmol/L) to address frequent potassium deficiency.
Safety in Malnutrition	Not recommended; high sodium can be dangerous.	Specifically formulated to meet altered electrolyte needs.
Risk Factor	Can cause electrolyte imbalance in malnourished patients.	Reduces risk of fluid overload and electrolyte complications when used correctly.

Intravenous Rehydration: Use with Extreme Caution

Intravenous (IV) rehydration is strongly discouraged in malnourished patients unless there is severe dehydration with shock or a patient is unable to tolerate oral fluids. The cautious approach is based on the high risk of fluid overload, which can lead to heart failure and death. When IV fluids are necessary, a slow administration of specific solutions (e.g., half-strength Darrow's solution with 5% dextrose) and very close monitoring are critical.

Preventing and Managing Refeeding Syndrome

Refeeding syndrome is a severe metabolic disturbance that can occur when nutrition is reintroduced to a severely malnourished person. The metabolic shifts can cause dangerous complications affecting the heart, lungs, and brain. It is important to treat dehydration before beginning feeding, but the risk of refeeding syndrome remains.

Electrolyte Deficiencies: Key deficiencies include phosphate, potassium, and magnesium.
Initial Feeding: After rehydration, start with small, frequent feeds of a low-osmolality, low-lactose formula, like F-75 therapeutic milk, and gradually increase intake.
Monitoring: Closely monitor blood electrolyte levels and clinical signs of refeeding syndrome, such as swelling (oedema), muscle weakness, or changes in heart rate.

Nutritional Support Post-Rehydration

Once the initial rehydration phase is complete, nutritional rehabilitation is crucial for recovery. The process must be slow and carefully managed. This includes:

Milk-Based Formulas: Use a formula like F-75, designed to provide adequate calories and protein without overwhelming the system.
Micronutrient Supplementation: Malnourished patients also need supplements of vitamins (like Vitamin A) and minerals (including zinc and copper).
Continued Monitoring: Ongoing assessment of the patient's weight, feeding tolerance, and overall status is essential to a successful recovery. For more on specific protocols, authoritative sources like the World Health Organization provide detailed guidance on the management of severe acute malnutrition (SAM).

Conclusion

Fixing dehydration in malnutrition requires a specialized, cautious, and medically supervised approach. Unlike standard rehydration, the process involves using tailored solutions like ReSoMal, reserving IV fluids for shock only, and carefully managing the refeeding process to prevent dangerous complications. By following established guidelines and monitoring patients closely, healthcare professionals can navigate these risks and ensure a safer path to recovery for those affected by malnutrition.

Frequently Asked Questions

Using standard ORS on a malnourished person is dangerous primarily because it has high sodium content and low potassium content, which can worsen existing electrolyte imbalances, potentially leading to fatal complications like heart failure.

ReSoMal is a special oral rehydration solution formulated for malnourished patients. It contains lower sodium and higher potassium levels than standard ORS, which is safer for their altered electrolyte balance and helps prevent fluid overload.

IV fluids should be used only in cases of severe dehydration with shock or when a patient cannot tolerate oral or nasogastric rehydration. Even then, it should be administered slowly and under close medical supervision.

Refeeding syndrome is a metabolic complication that occurs when nutrition is reintroduced to a severely malnourished person. It causes dangerous shifts in fluids and electrolytes, which can lead to organ dysfunction and be fatal.

The most common and dangerous electrolyte deficiencies seen in refeeding syndrome are hypophosphatemia (low phosphate), hypokalemia (low potassium), and hypomagnesemia (low magnesium).

For a very weak or ill malnourished child, rehydration may be administered orally in small, frequent sips, or via a nasogastric tube if they cannot drink effectively.

The initial feeding should be small, frequent, and consist of a low-osmolality, low-lactose formula, such as F-75 therapeutic milk, to begin nutritional rehabilitation cautiously and avoid complications.