What fluid do they give you in the hospital?: A Guide to Intravenous Fluids

October 12, 2025 •

5 min read

Intravenous (IV) fluids are among the most common medical treatments administered in a hospital setting, with a primary purpose of preventing or treating dehydration. Understanding exactly what fluid do they give you in the hospital is key to comprehending this fundamental aspect of patient care.

Quick Summary

This guide explains the primary types of intravenous fluids used in hospitals, including common crystalloids like saline and Lactated Ringer's, as well as colloids. It details their compositions, indications for use, and how healthcare providers select the appropriate fluid based on a patient's specific needs and condition.

Key Points

Crystalloids are the most common IV fluids, including normal saline (0.9% NaCl) and Lactated Ringer's solution, used for hydration and resuscitation due to their small, dissolved molecules.
Normal saline is ideal for expanding extracellular volume, often used with blood transfusions, but large volumes can cause metabolic acidosis.
Lactated Ringer's is a balanced solution, often preferred for sepsis and burns due to its electrolyte content being closer to plasma, which helps prevent acidosis.
Dextrose solutions provide energy and free water, making them useful for low blood sugar, but they are not suitable for aggressive fluid resuscitation.
Colloids contain larger molecules, such as albumin, and are used for targeted plasma volume expansion in specific critical conditions like severe burns or shock.
Fluid selection depends on the patient's specific needs, with healthcare providers considering the cause of fluid imbalance and any underlying conditions before making a choice.

When a patient receives an intravenous (IV) drip in the hospital, the fluid delivered isn't just plain water. Healthcare providers carefully select specific solutions to address the patient's condition, whether it's for hydration, medication delivery, or critical fluid resuscitation. These fluids fall into two main categories: crystalloids and colloids. The selection of fluid is a critical clinical decision, influenced by the patient's health status, the cause of their fluid imbalance, and their specific electrolyte needs.

Crystalloids: The Most Common IV Fluids

Crystalloids are water-based solutions containing small, dissolved molecules like electrolytes that can easily pass from the bloodstream into tissues and cells. They are the most frequently used IV fluids for routine hydration and fluid replacement.

Normal Saline (0.9% NaCl)

Normal saline, a sterile solution of 0.9% sodium chloride dissolved in water, is a cornerstone of IV therapy and one of the most widely used fluids.

Key facts: It is an isotonic solution, meaning its concentration of solutes is similar to that of blood plasma.
Common uses: Normal saline is the fluid of choice for expanding extracellular fluid volume, and is used to treat dehydration, hypovolemia (low blood volume), and blood loss. It is also the standard fluid for administering alongside blood transfusions.
Considerations: While effective, infusing large volumes of normal saline can lead to hyperchloremic metabolic acidosis due to its higher-than-plasma chloride concentration.

Lactated Ringer's (LR)

Lactated Ringer's solution is a balanced crystalloid that contains sodium, chloride, potassium, calcium, and lactate. It is often preferred for fluid resuscitation in various clinical situations, including sepsis, burns, and trauma.

Key facts: Its electrolyte composition is more closely aligned with the body's plasma compared to normal saline, which can help prevent acidosis. The lactate is metabolized by the liver into bicarbonate, a base that helps buffer blood pH.
Common uses: LR is used to treat dehydration, correct sodium depletion, and manage significant fluid losses, such as from burns or gastrointestinal fistulas.
Considerations: LR contains calcium, which makes it incompatible with some medications, including certain antibiotics, and cannot be administered in the same line as a blood transfusion due to the risk of clotting.

Dextrose Solutions (e.g., D5W)

Dextrose solutions contain glucose (a simple sugar) in sterile water. The most common is 5% dextrose in water (D5W).

Key facts: While initially an isotonic solution, the body rapidly metabolizes the glucose, leaving only free water. This effectively makes it a hypotonic solution in the body, which can shift fluid into the cells.
Common uses: Dextrose provides calories and a source of water to prevent dehydration and correct high serum osmolality. It is also used to treat low blood sugar (hypoglycemia).
Considerations: Dextrose is not suitable for aggressive fluid resuscitation because it can cause hyperglycemia (high blood sugar) and potentially lead to cerebral edema (brain swelling).

Colloids: For Specific and Targeted Fluid Support

Colloid solutions contain larger molecules, such as proteins or synthetic starches, that do not easily cross cell membranes. This allows them to stay in the blood vessels for longer, providing a more sustained volume-expanding effect.

Albumin

Albumin is a naturally occurring protein colloid derived from human plasma.

Key facts: As a key protein in blood, albumin plays a vital role in regulating oncotic pressure, which keeps fluid within the blood vessels. Supplementing it can draw excess fluid from tissues back into the bloodstream.
Common uses: It is used in patients with low protein levels (hypoalbuminemia) and conditions like severe burns, sepsis, and some types of shock.
Considerations: Albumin is more expensive than crystalloids and carries a small risk of allergic reactions.

Synthetic Colloids (e.g., Hetastarch, Dextran)

These are artificially created molecules used for volume expansion.

Key facts: Synthetic colloids were once used to manage significant blood loss, but their use has declined due to growing evidence of potential adverse effects.
Risks: They are associated with complications such as allergic reactions, blood clotting disorders, and kidney damage.

Comparison of Common Intravenous Fluids


Feature	Normal Saline (0.9% NaCl)	Lactated Ringer's (LR)	Albumin	Dextrose 5% in Water (D5W)
Classification	Isotonic Crystalloid	Isotonic Crystalloid (Balanced)	Colloid (Derived from human plasma)	Initially Isotonic, becomes Hypotonic
Composition	Water, Sodium Chloride	Water, Sodium Chloride, Potassium, Calcium, Lactate	Water, Human Albumin	Water, Glucose
Main Use	Extracellular volume expansion, blood transfusions	Broad fluid resuscitation, burns, sepsis	Expanding blood volume, severe burns, hypoalbuminemia	Providing free water, calories; treating hypoglycemia
Primary Benefit	Safe, versatile, cost-effective, compatible with blood	More physiological electrolyte profile, less prone to causing acidosis	Sustained plasma volume expansion, pulls fluid into vessels	Provides energy, corrects free water deficit
Primary Risk	Hyperchloremic metabolic acidosis with large volumes	Incompatibility with certain drugs and blood transfusions	More expensive, small risk of allergic reaction	Can cause hyperglycemia, not suitable for resuscitation

Clinical Reasons for Giving IV Fluids

Beyond general rehydration, healthcare professionals administer IV fluids for several key reasons, with the specific solution tailored to the clinical need.

Fluid Resuscitation: In cases of severe volume depletion, such as hypovolemic shock resulting from trauma, blood loss, or sepsis, rapid IV fluid administration is necessary to restore adequate tissue perfusion.
Electrolyte Replacement: For patients with significant electrolyte imbalances, IV fluids can help restore the proper balance of minerals like sodium, potassium, and calcium, which are vital for nerve and muscle function.
Medication Delivery: The IV line provides a direct route into the bloodstream, allowing for rapid and precise delivery of medications, antibiotics, or chemotherapy that cannot be taken orally.
Maintenance Fluid Therapy: For patients who are unable to eat or drink, or require prolonged nutritional support, IV fluids can provide their daily water and electrolyte requirements.

The Clinical Decision-Making Process

Deciding which fluid to administer is not a simple choice; it requires a comprehensive assessment of the patient's overall health. A healthcare provider will consider factors such as:

The patient's underlying medical conditions (e.g., kidney disease, heart failure).
The type and amount of fluid loss.
The patient's current electrolyte and acid-base balance.
The presence of severe inflammation or systemic infection. This complex process is why different fluids are used for different conditions. For example, a patient with a traumatic brain injury may be given normal saline to avoid fluid shifts that could worsen cerebral edema, whereas a patient with severe pancreatitis may benefit from Lactated Ringer's.

Conclusion

The choice of what fluid do they give you in the hospital is a nuanced medical decision based on the specific clinical needs of each patient. From the common and versatile Normal Saline to the balanced Lactated Ringer's and the targeted colloid solutions, a variety of IV fluids serve distinct and critical functions in patient care. The right fluid can help restore hydration, balance electrolytes, deliver vital medications, and ultimately, support recovery by correcting the body's internal environment. The careful selection and monitoring of IV fluids by an interprofessional healthcare team are essential for ensuring patient safety and effective treatment outcomes.

For more information on the different types of IV fluids and their uses, consult a trusted medical resource such as the Cleveland Clinic on IV Fluids.

Frequently Asked Questions

Normal saline contains only sodium chloride and water, while Lactated Ringer's contains sodium, chloride, potassium, calcium, and lactate. LR is considered more balanced and physiological, as its electrolyte composition is closer to the body's plasma.

Dextrose, or glucose, is given intravenously to provide a source of water and carbohydrates (calories). It is commonly used to treat low blood sugar (hypoglycemia) and to provide energy for patients unable to eat or drink.

No, IV fluids are not just salt water. While normal saline is a salt-and-water solution, there are many types of IV fluids with different compositions, including dextrose solutions and more complex mixtures like Lactated Ringer's, which also contains potassium and calcium.

Colloids are IV solutions that contain large molecules, such as proteins or starches, that stay in the bloodstream longer than crystalloids. They are used for specific conditions requiring rapid and sustained expansion of blood volume, such as severe burns, shock, and hypoalbuminemia.

The choice depends on the patient's clinical needs. Lactated Ringer's is often preferred for fluid resuscitation in conditions like sepsis because it is less likely to cause metabolic acidosis. However, normal saline is necessary in some situations, such as when administering blood transfusions.

While generally safe, IV fluid administration carries some risks. These can include fluid overload, electrolyte imbalances, infection at the IV site, or allergic reactions, particularly with colloid solutions.

A doctor decides based on a comprehensive patient assessment. They consider the cause of the fluid imbalance, the patient's current electrolyte and acid-base levels, and any underlying conditions like heart or kidney problems.