Guide to Crystalloids and Colloids

Infusion fluids fall into two categories: crystalloids and colloids. Crystalloid solutions are plasma volume expanders that contain crystals such as electrolytes like sodium and potassium. These crystals are capable of fully dissolving into solution and allow the solution to move through membranes. Crystalloid solutions are mainly used to increase the intravascular volume when it is reduced. Some crystalloid solutions are used in specific circumstances to replace electrolyte losses or glucose as indicated. Crystalloids are typically used to replace fluids loss with hemorrhage, dehydration, and fluid loss due to surgery.

Colloids are gelatinous solutions with large molecules that act as plasma volume expanders. Particles in the colloid solution are too large to pass a semipermeable membrane, such as capillary membranes and stay in the intravascular spaces longer than crystalloids. Fluids in the colloid group are albumin, dextran, and hetastarch. These fluids are typically used to maintain circulating fluid volume after blood loss from trauma or surgery. Colloid administration is prone to increased risk of side effects.

It is important for all nurses to understand fluids, their properties and proper use and side effects of administration. Print and use this resource as a quick reference guide!
Please note: These lists are for reference and educational use only. Pedagogy does not recommend the use of any product or product manufacturer. 

Guide to Crystalloids and Colloids

Crystalloid Action / Use Nursing Considerations
Hypotonic: <250 mOsm/L
0.25% normal saline (NS)
0.33% NS
0.45% NS
5% dextrose in water (D5W)-hypotonic once administered
· Shifts fluid out of vessels into cells
· Hydrates cells
· D5W spares protein, provides calories and free water, treats hyperkalemia, is a diluent for IV drugs
· May worsen hypotension
· Can increase edema
· May cause hyponatremia
· D5W may also irritate veins
· Do not give to those at risk for increased intracranial pressure: stroke, head trauma or neurosurgery
Isotonic: >250 mOsm/L
0.9% NS
Lactated Ringer’s (LR)
· No fluid shift
· Vascular expansion
· Electrolyte replacement
· May cause fluid overload, especially with hypertension and heart failure
· Generalized edema,
· Dilutes hemoglobin
· May cause electrolyte imbalance
Hypertonic: >375 mOsm/L
D50.45% NS
D50.9% NS
Hypertonic saline (HS)
3% or 5%
· Shifts fluid back into circulation
· Vascular expansion
· Replaces electrolytes
· Irritating to veins
· May cause fluid overload
· May cause hypernatremia
· May cause hyperchloremia
· HS slows inflammation and increases capillary permeability
Colloids Action / Use Nursing Considerations
(plasma protein)
5% or 25%
· Keeps fluid in vessels
· Maintains volume
· Used to replace protein and treat shock and erythroblastosis fetalis
· May cause anaphylaxis (watch for hives, fever, chills, headache).
· May cause fluid overload and pulmonary edema
Hetastarch (HES)
(synthetic starch)
6% or 10%
· Shifts fluid into vessels
· Vascular expansion
· Prolongs hemodynamic response when given with hypertonic saline
· May cause fluid overload and hypersensitivity
· Increased risk of bleeding contraindicated in bleeding disorders, CHF, and renal failure
40 kDa or 70 kDa
· Shifts fluids into vessels
· Vascular expansion
· Prolongs hemodynamic response when given with hypertonic saline
· May cause fluid overload and hypersensitivity
· Contraindicated in bleeding disorders, CHF, and renal failure

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