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# IV solutions from the nursing side

- Fundamental

Isotonic solutions stay in the vessels, hypotonic ones move into cells, and hypertonic ones draw water out of cells.

Updated Nov 5, 2026

## Key points

- Isotonic: 0.9 % saline and lactated Ringer's; watch for volume overload.
- 5 % dextrose in water is isotonic in the bag but acts as hypotonic once the glucose is metabolised: it is not for resuscitation.
- Hypotonic (0.45 % saline): risk of cerebral oedema, hypotension and confusion.
- Hypertonic (3 % saline): for severe hyponatraemia and cerebral oedema; monitor serum sodium.
- An infusion pump is the safest way to give an exact volume.
- Check compatibility before connecting a secondary infusion.

On this page

- The basics Key points
- What it is
- Key points
- Components
- What it is for
- What to watch with each type of solution
- Common mistakes
- Elsewhere in DurgiPedia

- Safety In nursing practice

- Study Test yourself

- Connections Connections

## What it is

Nurses do not choose the solution, but they must know what each one does in order to monitor the patient. A solution is defined by its tonicity compared with plasma: an isotonic solution does not move water between vessels and cells; a hypotonic one moves it into cells; a hypertonic one draws it out. Each group has its own uses and risks. This page covers the nursing view; the physiology is on the tonicity page.

## Key points

- Tonicity compares the particle concentration of the solution with that of plasma.
- Isotonic: water stays where it is; it expands the volume inside the vessels.
- Hypotonic: water moves into the cells.
- Hypertonic: water moves out of the cells into the vessels.
- Kidney patients and small children usually need smaller volumes.

## Components

- Isotonic: 0.9 % saline, lactated Ringer's, 5 % dextrose in water (in the bag).
- Hypotonic: 0.45 % saline; 5 % dextrose in water once metabolised.
- Hypertonic: 3 % saline, 5 % dextrose with 0.45 % saline, 5 % dextrose with lactated Ringer's.

## What it is for

- 0.9 % saline: haemorrhage, severe vomiting or diarrhoea, tube losses, drains, mild hyponatraemia and transfusions.
- Lactated Ringer's: resuscitation, gastrointestinal losses, burns, trauma, metabolic acidosis and surgery.
- 5 % dextrose in water: free water, hypernatraemia and a glucose supply.
- Hypotonic: intracellular dehydration and hypernatraemia.
- Hypertonic: severe hyponatraemia and cerebral oedema, in critical-care settings.

## What to watch with each type of solution

| Type | Examples | Effect | What the nurse watches |
| --- | --- | --- | --- |
| Isotonic | 0.9 % saline, lactated Ringer's | Expands volume in the vessels | Overload: breathlessness, crackles, oedema, high blood pressure; more in heart or kidney failure |
| Isotonic that becomes hypotonic | 5 % dextrose in water | Supplies free water | Not for resuscitation; watch for cerebral oedema and blood glucose |
| Hypotonic | 0.45 % saline | Moves water into cells | Hypotension, confusion, cerebral oedema; avoid in liver disease, trauma and burns |
| Hypertonic | 3 % saline | Draws water out of cells | Serum sodium, overload, breathing difficulty; avoid in heart or kidney failure |

## In nursing practice

- Watch skin turgor, urine output, lung sounds, oxygen needs and new oedema.
- Lactated Ringer's is not used if serum pH is above 7.5 and may raise potassium in kidney failure.
- In a fasting patient, fluids may start faster and are reduced as oral intake resumes.
- With gravity infusions, keep the drip chamber a quarter to half full.
- Review the need for fluids with the provider regularly.

## Common mistakes

- Thinking 5 % dextrose in water replaces volume like 0.9 % saline.
- Not watching for overload in older adults or in heart or kidney failure.
- Connecting a secondary infusion without checking compatibility: a precipitate can form.
- Not checking the drop factor of the set before calculating a gravity drip rate.

## Test yourself

Think of the answer, then tap the question to see it.

## Why is 5 % dextrose in water not used to resuscitate a patient in shock?

Because once the glucose is metabolised, free water is left that moves into cells: it does not stay in the vessels and can cause cerebral oedema.

## Which complication is watched for above all with isotonic solutions?

Volume overload: breathlessness, crackles, oedema and rising blood pressure, especially in heart or kidney failure.

## In which patients are hypotonic solutions avoided?

In patients with liver disease, trauma or burns, and when cerebral oedema is a concern, because they move water into the cells.

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## Elsewhere in DurgiPedia

- [IV fluids: tonicity and where they go](https://durgical.com/en/physiology/iv-fluids-tonicity-and-where-they-go/)

## Connections

## Related 2

- [Fluid balance: recording intake and output](https://durgical.com/en/nursing/fluid-balance-recording-intake-and-output/)
- [Caring for a peripheral IV line: flushing, dressing and when to remove it](https://durgical.com/en/nursing/caring-for-a-peripheral-iv-line-flushing-dressing-and-when-to-remove-it/)

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Educational content for students; it does not replace your institution's protocols, supervised clinical training or a prescriber's order. Dose-calculation examples use made-up numbers: they are educational, not a clinical order.

Sources: [Nursing Fundamentals, 15.3 Intravenous Solutions](https://med.libretexts.org/Bookshelves/Nursing/Nursing_Fundamentals_(OpenRN)/15%3A_Fluids_and_Electrolytes/15.03%3A_Intravenous_Solutions) (Open RN (Chippewa Valley Technical College), LibreTexts, 2021); [Nursing Skills, 23.2 IV Therapy Basics](https://med.libretexts.org/Bookshelves/Nursing/Nursing_Skills_(OpenRN)/23%3A_IV_Therapy_Management/23.02%3A_IV_Therapy_Basics) (Open RN (Chippewa Valley Technical College), LibreTexts, 2021).

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