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General information only, not medical advice.
Short answer
Intravenous infiltration is the inadvertent delivery of a nonvesicant fluid or medication into the tissue around a vein instead of into the vessel, with the potential to harm the patient. When the leaked fluid is a vesicant, the event is called extravasation. Typical signs are swelling, pain, cool skin and pale or red colour around the IV site.
Definition and scope
A 2018 Journal of Infusion Nursing study of peripheral infiltration and extravasation (Odom, Lowe and Yates) describes infiltration as the inadvertent delivery of nonvesicant fluid or medication into surrounding tissue, with the potential to harm the patient, and states that “Vesicant fluid that has leaked into the tissue space is called extravasation.” St. Jude Children’s Research Hospital (page reviewed March 2025) describes the same event in plain terms: medicines or fluids “leak out into the tissues under the skin instead of going into the bloodstream,” and with certain medicines the leak can cause tissue damage (necrosis), with peeling and blisters.
When reading any paper, check how it defines “infiltration” and how it grades severity before comparing numbers.
How it is recognised in practice
St. Jude lists these signs: swelling around the site; a tight or puffy feeling; pain or discomfort near the site; skin that feels cool; and redness or pale colour.
Clinical papers go further and grade severity. Two scales appear in the published studies cited here, and they are not interchangeable:
| Scale | Where it appears | What it describes |
|---|---|---|
| Pediatric PIV Infiltration Scale (adapted from Children’s Medical Center, Dallas; not an Infusion Nurses Society scale) | Odom et al., 2018, Table 1 | Grade 3: moderate swelling, pain, cool skin, blanching and a diminished pulse below the site. Grade 4: severe swelling, skin breakdown or necrosis, blistering, and an absent or diminished pulse; also infiltration of blood products, irritants or vesicants “regardless of appearance.” |
| 0-4 grading after Flemmer and Chan | Park et al., 2016 | Uses measured swelling: slight is under 1 inch, moderate is 1-6 inches, severe is over 6 inches. |
One practical consequence: a “grade 3” in one hospital’s paper is not necessarily the same finding as a “grade 3” in another’s, because the criteria differ.
Risk factors and who is affected
Odom et al. identify neonates as the highest-risk group, because of thinner skin layers and smaller, more fragile blood vessels. They also list infusate properties (vesicants such as calcium, potassium and parenteral nutrition; osmolality, pH and exposure duration), the insertion site, constant movement, and a patient’s inability to communicate pain.
Published pediatric rates vary widely. Odom et al. cite reported ranges of 10% to 30% (Treadwell) and up to 58% (Gault) for pediatric patients, and for neonates up to 55% (Treadwell) and as high as 70% (Irving). These are figures cited from other studies, not an incidence measured by Odom et al., whose own paper reviewed 147 cases at Arkansas Children’s Hospital in 2014-2015.
In one South Korean hospital cohort of 1,174 hospitalized children, Park et al. recorded 92 infiltrations (7.8%). Their multivariate analysis found these associations:
| Factor | Odds ratio (95% CI) |
|---|---|
| Phenytoin | 11.03 (2.92-41.68) |
| 10% dextrose | 6.55 (2.36-18.20) |
| Steroids | 6.21 (2.04-18.91) |
| Vancomycin | 4.10 (1.17-14.30) |
| High-concentration electrolytes | 3.49 (1.13-10.82) |
| Ampicillin/sulbactam | 3.37 (1.91-5.94) |
| Lower-limb IV site | 1.72 (1.02-2.92) |
These are associations in one hospital cohort of children, not a ranking of drugs and not a statement about adults or other settings.
Where it matters for labs, clinics and supply decisions
Infiltration is one of the complications that IV catheter selection, securement and site visibility are meant to help staff watch for. The related CASRAI guides cover those topics from the product side:
- What an IV catheter is describes the transparent or gauze dressing that keeps the site visible for signs of infiltration or infection, and notes that guidance has moved toward replacing a peripheral IV when clinically indicated, for example on signs of infiltration, phlebitis or infection.
- The StatLock guide records a manufacturer claim from BD that up to 48% of tape-secured IV catheters result in complications such as phlebitis and infiltration. It is a manufacturer statement, not an independent measurement.
- IV catheter gauge selection covers gauge sizes, relevant because small, fragile veins are part of the risk picture above.
- IV start kits and infusion pumps cover the other supplies in the same setup.
Common misunderstandings
- “Infiltration and extravasation are the same thing.” In the definitions above, the difference is whether the leaked fluid is a vesicant.
- “Grades are universal.” The pediatric scale in Odom et al. and the 0-4 scale in Park et al. use different criteria.
- “The reported rate is the rate.” Figures range from 7.8% in one hospital cohort to as high as 70% in neonates in cited work, depending on population, definition and method.
- “It looks mild, so it is mild.” The pediatric scale in Odom et al. grades infiltration of blood products, irritants or vesicants as grade 4 regardless of appearance.
FAQ
What is the difference between infiltration and extravasation?
Infiltration is leakage of a nonvesicant fluid or medication into surrounding tissue; extravasation is leakage of a vesicant (Odom et al., 2018). St. Jude describes extravasation as certain medicines causing tissue damage (necrosis) after infiltration.
What are the signs of IV infiltration?
St. Jude lists swelling, a tight or puffy feeling, pain or discomfort near the site, cool skin, and redness or pale colour.
Which patients are at higher risk?
Neonates are described as the highest-risk group, and the risk list also includes vesicant or high-osmolality infusates, movement at the site and patients who cannot communicate pain (Odom et al., 2018). In the Park et al. cohort, lower-limb sites were associated with higher odds (1.72).
Sources
- Odom B, Lowe L, Yates C. Peripheral Infiltration and Extravasation Injury Methodology: A Retrospective Study. J Infus Nurs 2018;41(4):247-252. https://pmc.ncbi.nlm.nih.gov/articles/PMC6082416. Checked 2026-10-30.
- Park SM, Jeong IS, Jun SS. PLoS One 2016;11(6):e0158045. https://pmc.ncbi.nlm.nih.gov/articles/PMC4924835/. Checked 2026-10-30.
- St. Jude Children’s Research Hospital, IV infiltration and extravasation (reviewed March 2025). https://together.stjude.org/en-us/treatment-tests-procedures/symptoms-side-effects/iv-infiltration-and-extravasation.html. Checked 2026-10-30.
