IV Y-Site Compatibility Checker
Instantly verify whether two IV medications can be co-administered through the same line. Built for nurses and pharmacists — with clinical mechanisms, FDA warnings, and direct links to verify every result.
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Understanding IV Y-Site Compatibility
Clinical education for nursing students and practicing nurses
What is a Y-Site?
A Y-site is the injection port on IV tubing that allows a secondary medication to enter the same line as a primary infusion. When two drugs meet at this junction, they mix briefly before entering the patient — creating the potential for physical or chemical incompatibility.
Why It Matters
Incompatible drugs can form precipitates that occlude catheters, cause phlebitis, or enter the bloodstream and cause pulmonary emboli. In neonates, ceftriaxone-calcium precipitates have caused fatal organ damage. Incompatibility can also inactivate medications, leading to therapeutic failure.
Trissel's Compatibility Codes
| Code | Meaning | Clinical Action |
|---|---|---|
| C | Compatible | May co-infuse at concentrations matching the published study. Verify concentration and diluent. |
| I | Incompatible | Hard stop. Do not co-infuse. Use separate lines or flush ≥20 mL NS between drugs. |
| V | Variable | Treat as incompatible. Results depend on concentration, diluent, or temperature. Consult pharmacy. |
| U | Unknown / No Data | Treat as incompatible. No published study exists. Use separate lines until pharmacy confirms. |
Common Incompatibility Mechanisms
pH Precipitation
Most common mechanism. Drugs formulated at extreme pH (e.g., phenytoin pH 12, furosemide pH 9) precipitate when mixed with acidic drugs. The resulting particles can be subvisible — invisible to the naked eye but still dangerous.
Ionic Reaction
Divalent cations (Ca²⁺, Mg²⁺) react with anionic drugs (ceftriaxone, phosphate) to form insoluble salts. The ceftriaxone-calcium reaction carries an FDA black box warning after neonatal fatalities.
Lipid Emulsion Cracking
Acidic drugs or high electrolyte concentrations disrupt propofol's lipid emulsion, causing phase separation and large lipid globules. These can cause fat emboli if infused.
Oxidation / Degradation
Some drugs (norepinephrine, dobutamine) oxidize when exposed to alkaline pH or light, causing color changes and loss of potency. A brown or black discoloration is a sign of degradation — discard immediately.
Authoritative References
The most trusted resource for injectable drug information. Includes 400+ monographs with Y-site compatibility tables. Published by the American Society of Health-System Pharmacists.
The industry-standard database for IV compatibility data, available via Lexicomp (Wolters Kluwer) and Micromedex. Contains thousands of Y-site compatibility studies with concentration-specific data.
Comprehensive IV drug compatibility and stability reference covering 580+ injectable drugs in 12 fluids. Updated quarterly. Widely used in hospital pharmacies across North America.
Official FDA safety alerts regarding IV drug incompatibilities, including the ceftriaxone-calcium black box warning (2009) and neonatal fatality reports.
Peer-reviewed literature on Y-site compatibility studies. Includes landmark studies such as Kufel et al. (2017) on vancomycin-piperacillin-tazobactam incompatibility and Trissel's original research.
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