Why does intravenous (IV) potassium cause a burning sensation?

Why IV Potassium Causes a Burning Sensation

IV potassium causes a burning sensation because potassium-containing solutions are intrinsically irritating to tissues, producing chemical phlebitis and venospasm at the infusion site. 1

Mechanism of Pain and Tissue Irritation

The burning sensation occurs through direct chemical irritation of the vein wall and surrounding tissues:

• Potassium solutions are inherently tissue-irritating, causing chemical phlebitis (inflammation of the vein) and venospasm (spasm of the vein wall) during infusion 1
• The irritation is concentration-dependent, with concentrations greater than 80-100 mEq/L producing significant patient intolerance and pain 2
• Local tissue damage can progress to necrosis and subsequent sloughing if extravasation occurs (leakage outside the vein) 1

Clinical Manifestations

Patients experience several adverse effects related to IV potassium administration:

• Pain at the infusion site is the most common complaint, often described as burning or stinging 1, 2
• Venous thrombosis or phlebitis may extend from the injection site 1
• Transient adverse effects including discomfort occur even with properly administered infusions 2

Strategies to Minimize Discomfort

Adding lidocaine 50 mg to potassium infusions significantly reduces pain perception compared to potassium alone 2:

• A randomized, double-blind study demonstrated statistically significant reduction in pain when lidocaine was added to KCl 20 mEq/65 mL infusions 2
• Pain assessment by both verbal descriptor and visual analog scales showed clear improvement in patient tolerance with lidocaine addition 2

Additional protective measures include:

• Avoid peripheral infusions of high-concentration potassium (>80-100 mEq/L) whenever possible 2
• Ensure proper IV placement to prevent perivascular infiltration, which can cause local tissue necrosis 1
• Slow infusion rates help reduce the intensity of venous irritation 1

Management of Extravasation

If perivascular infiltration occurs, immediate intervention is required:

• Discontinue the IV infusion at that site immediately 1
• Local infiltration with procaine hydrochloride 1% (to which hyaluronidase may be added) reduces venospasm and dilutes remaining potassium in tissues 1
• Local application of heat may provide additional relief 1

Important Clinical Caveat

The burning sensation from IV potassium is a local tissue irritation phenomenon and should not be confused with systemic potassium toxicity, which manifests as paresthesias of extremities, muscle weakness, cardiac arrhythmias, and ECG changes 1, 3. The local burning is uncomfortable but expected, while systemic symptoms indicate dangerous hyperkalemia requiring immediate intervention.