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Klor-Con / 25 Side Effects

Generic Name: potassium chloride

Note: This page contains information about the side effects of potassium chloride. Some of the dosage forms included on this document may not apply to the brand name Klor-Con / 25.

For the Consumer

Applies to potassium chloride: controlled-release tablets, extended-release capsules, extended-release tablets, microencapsulated

Check with your doctor if any of these most COMMON side effects persist or become bothersome:

Diarrhea; gas; nausea; stomach discomfort; vomiting.

Seek medical attention right away if any of these SEVERE side effects occur while taking potassium chloride (the active ingredient contained in Klor-Con / 25)

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); black, tarry stools; chest pain; irregular heartbeat; listlessness; numbness or tingling in your skin, lips, hands, or feet; severe nausea or vomiting; stomach pain or swelling; unusual confusion or anxiety; unusual muscle weakness or paralysis; vomit that looks like coffee grounds; weak or heavy legs.

For Healthcare Professionals

Applies to potassium chloride: compounding powder, intravenous solution, oral capsule extended release, oral granule extended release, oral liquid, oral powder for reconstitution, oral tablet, oral tablet extended release


Metabolic side effects have been reported rarely and have usually resulted from hyperkalemia. The risk of hyperkalemia is relatively high in patients with preexisting renal insufficiency.[Ref]

Signs of hyperkalemia include muscle weakness, including frank skeletal muscle and diaphragm paralysis, cardiac arrhythmias, and ECG changes. Common ECG changes associated with hypokalemia include loss of P waves, wide QRS complexes, decreased rate, and conduction disturbances. If toxicity is suspected or documented, potassium should be stopped immediately. While monitoring the ECG, a combination of dextrose and insulin in a ratio of 3 g of dextrose for every 1 unit of insulin may be administered. Sodium bicarbonate 50 to 100 mEq and calcium gluconate 10% intravenously may be helpful if acidosis is present. Potassium-binding resins or dialysis may be necessary in serious cases.

A 74-year-old woman receiving chronic intermittent hemodialysis treatment three times a week for 5 months developed cardiopulmonary arrest secondary to severe hyperkalemia on two separate occasions. The patient had a history of nephrolithiasis, hypertension, renal vascular disease, and chronic obstructive pulmonary disease (30-year history of smoking). A potassium-containing salt substitute was a probable cause.

The Boston Collaborative Drug Surveillance Program monitored 16,048 consecutive patients. of whom 4,921 (31%) had received potassium chloride (KCl). Adverse reactions were reported in 5.8%, the most common being hyperkalemia

Hyperkalemia is significantly more likely after intravenous administration and in elderly patients with uremia who receive high doses.[Ref]


Gastrointestinal (GI) side effects have been reported from orally administered potassium chloride (the active ingredient contained in Klor-Con / 25) They have included bad taste or aftertaste, nausea (10% to 30%), abdominal pain (20%), diarrhea (25%), dyspepsia or "heartburn" (5% to 20%) and GI ulceration. They have rarely included gastric or small bowel obstruction associated with the use of solid preparations.[Ref]

In a large, retrospective study of 104,908 patients, the reported incidence of upper GI tract bleeding was 0.3% to 0.4%, depending on the type of KCl preparation. The risk of GI bleeding was approximately 30% lower with use of a microencapsulated KCl preparation compared with a wax-matrix preparation.

All solid KCl preparations can cause erosive damage to the GI mucosa, especially when they are administered in high doses with an anticholinergic agent. Anticholinergic agents increase GI transit (and potassium-mucosa contact) time.

The incidence of small bowel ulceration associated with encapsulated or wax-matrix KCl is relatively low, averaging less than 1 per 100,000 patient-years. The incidence of small bowel lesions associated with enteric-coated KCl is higher, averaging 40 to 50 per 100,000 patient-years.

Patients at higher risk of GI lesions include the elderly, the immobile and those with scleroderma, diabetes mellitus, mitral valve replacement, cardiomegaly or esophageal stricture. These problems were so much more common with the use of enteric-coated KCl, this form of the drug was withdrawn from the market in 1965.

The pathogenesis of potassium-induced ulceration is not known, but may be direct mucosal injury or induction of local mesenteric vascular insufficiency.

Nearly half of all patients complain of a bad taste or aftertaste.

Liquid KCl may be a better choice for patients with a history of esophageal stenosis or left atrial enlargement.[Ref]


Local side effects related to intravenous administration have included phlebitis or erythema at the injection site and pain with infusion.[Ref]

Local reactions related to intravenous administration of KCl occur in up to 25% of patients. Diluting 40 mEq or less of KCl in 1 liter or more of intravenous solution and administering this concentration in no less than 1 hour is strongly recommended to reduce the likelihood of these problems. If the clinical situation is not critical and the patient's serum K+ is 2.5 mEq/L or more, an infusion rate not to exceed 10 mEq/hour is recommended.

Limited data show that infusion pain was significantly less common among patients when KCl (in D5W) was infused with 50 mg of lidocaine compared with KCl infusions without lidocaine.[Ref]

Nervous system

A single case of paraplegia following epidural injection of 15 mL of 15% KCl and bupivacaine has been reported. The patient suffered permanent neurologic damage, which was thought to be due to the high extracellular concentration of potassium in the injection. Potassium salts are not routinely used as adjuvants to local anesthetics.[Ref]

Nervous system side effects have included a single report of paraplegia following epidural injection.[Ref]


Hypersensitivity side effects have been reported rarely. They have included a single case of contact dermatitis.[Ref]


Dermatologic side effects have rarely included skin rash.[Ref]


1. Wetli CV, Davis JH "Fatal hyperkalemia from accidental overdose of potassium chloride." JAMA 240 (1978): 1339

2. Lankton JW, Siler JN, Neigh JL "Letter: Hyperkalemia after administration of potassium from nonrigid parenteral-fluid containers." Anesthesiology 39 (1973): 660-1

3. Cox J, Starbuck M "Hyperkalemic cardiac arrest during an infusion of potassium chloride following an overdose of propranolol." Resuscitation 14 (1986): 255-6

4. Doorenbos CJ, Vermeij CG "Danger of salt substitutes that contain potassium in patients with renal failure." BMJ 326 (2003): 35-6

5. Shapiro S, Slone D, Lewis GP, Jick H "Fatal drug reactions among medical inpatients." JAMA 216 (1971): 467-72

6. Perez GO, Oster JR, Pelleya R, Caralis PV, Kem DC "Hyperkalemia from single small oral doses of potassium chloride." Nephron 36 (1984): 270-1

7. Illingworth RN, Proudfoot AT "Rapid poisoning with slow-release potassium." Br Med J 281 (1980): 485-6

8. Leiter LA, Josse RG, West ML, Halperin ML "Severe metabolic acidosis induced in a patient during fasting by KCl administration." Clin Invest Med 11 (1988): 266-70

9. Ward C, Hamid S, Dow J "Gastric complication of massive Slow-K overdose." Br J Surg 74 (1987): 490

10. Lawson DH "Adverse reactions to potassium chloride." Q J Med 43 (1974): 433-40

11. Lindeman RD "Hypokalemia: causes, consequences and correction." Am J Med Sci 272 (1976): 5-17

12. Ceuppens H, Hitchcock JF, Damen J, Jambroes G, Ae Dion R "Severe hypotension due to potassium-induced pericardial injury." Thorax 37 (1982): 546-7

13. Saxena K "Death from potassium chloride overdose." Postgrad Med 84 (1988): 97-8,101-2

14. Kallen RJ, Rieger CH, Cohen HS, Sutter MA, Ong RT "Near-fatal hyperkalemia due to ingestion of salt substitute by an infant." JAMA 235 (1976): 2125-6

15. Chakko SC, Frutchey J, Gheorghiade M "Life-threatening hyperkalemia in severe heart failure." Am Heart J 117 (1989): 1083-91

16. Kopman EA, Ramirez-Inawat RC "Persistent electromechanical cardiac arrest following administration of cardioplegic and glucose-insulin-potassium solutions." Anesth Analg 59 (1980): 69-71

17. Lawson DH "Clinical use of potassium supplements." Am J Hosp Pharm 32 (1975): 708-11

18. Chait L, Mandel WJ "Wolff-Parkinson-White syndrome: alterations in ventricular activation induced by changes in serum potassium." Chest 64 (1973): 780-1

19. McMahon FG, Ryan JR, Akdamar K, Ertan A "Upper gastrointestinal lesions after potassium chloride supplements: a controlled clinical trial." Lancet 2 (1982): 1059-61

20. Lewis JH "Gastrointestinal injury due to medicinal agents." Am J Gastroenterol 81 (1986): 819-34

21. Learmonth I, Weaver PC "Letter: Potassium stricture of the upper alimentary tract." Lancet 1 (1976): 251-2

22. "Potassium and gastrointestinal lesions. I." Nutr Rev 24 (1966): 138-41

23. Phillips BL "Potassium-induced bowel ulceration." Br J Clin Pract 28 (1974): 143-4

24. Folk FS, Spellman MW, Hoffler OW "Stenosing small bowl ulceration. Apparently secondary to enteric- coated potassium chloride." J Natl Med Assoc 61 (1969): p315-8assim

25. Roberts HJ "Potassium chloride and intestinal ulceration." Lancet 2 (1965): 1127

26. Naiken VS, Rachman R "Giant ulcers of the transverse colon." JAMA 217 (1971): 344

27. Moorhouse RA "Letter: Ulceration of small intestine and slow-release potassium tablets." Br Med J 3 (1975): 542

28. Trechot P, Moore N, Bresler L, Castot A, Gay G, Netter P, Royer R "Potassium chloride tablets and small bowel stenoses and perforations: two studies in the french pharmacovigilance system." Am J Gastroenterol 89 (1994): 1268

29. Sumithran E, Lim KH, Chiam HL "Atrio-oesophageal fistula complicating mitral valve disease." Br Med J 2 (1979): 1552-3

30. Holland GW "Stenosing ulcers of the small bowel associated with thiazide and potassium therapy." N Z Med J 64 (1965): 383-5

31. Leijonmarck CE, Fenyo G, Raf L "Nontraumatic perforation of the small intestine." Acta Chir Scand 150 (1984): 405-11

32. Watson MR, Mark JB "Ulceration of the small intestine. Relation to enteric-coated potassium." Am J Surg 112 (1966): 421-5

33. Cooper I "Potassium supplementation during diuretic therapy." Curr Ther Res Clin Exp 17 (1975): 555-63

34. Jacobs E, Pringot J "Gastric ulcers due to the intake of potassium chloride." Am J Dig Dis 18 (1973): 289-94

35. Skoutakis VA, Acchiardo SR, Wojciechowski NJ, Carter CA "Liquid and solid potassium chloride: bioavailability and safety." Pharmacotherapy 4 (1984): 392-7

36. Ball JR "Letter: Potassium strictures of the upper alimentary tract." Lancet 1 (1976): 495-6

37. Leijonmarck CE, Raf L "Gastrointestinal lesions and potassium chloride supplements." Lancet 1 (1985): 56-7

38. Ashby WB, Humphreys J, Smith SJ "Small-bowel ulceration induced by potassium chloride." Br Med J 5475 (1965): 1409-12

39. Lakhani M, Stewart WK "Hazards of potassium chloride solution." Lancet 2 (1985): 453

40. Antonescu CG, Barritt AS 3d "Potassium chloride and gastric outlet obstruction." Ann Intern Med 111 (1989): 855-6

41. Campbell JR, Knapp RW "Small bowel ulceration associated with thiazide and potassium therapy: review of 13 cases." Ann Surg 163 (1966): 291-6

42. Javett S "Slow k ulcer." S Afr J Surg 13 (1975): 64

43. Wynn V "Potassium chloride and bowel ulceration." Br Med J 5477 (1965): 1546

44. "Potassium chloride and bowel ulceration." Br Med J 5475 (1965): 1383-4

45. "Small-intestine ulceration and enteric-coated potassium chloride." Med Lett Drugs Ther 7 (1965): 57-8

46. Rosenthal T, Adar R, Militianu J, Deutsch V "Esophageal ulceration and oral potassium chloride ingestion." Chest 65 (1974): 463-5

47. Davies DR, Brightmore T "Idiopathic and drug-induced ulceration of the small intestine." Br J Surg 57 (1970): 134-9

48. Lech Y, Hey H, Jorgensen F, Matzen P, Ostergaard O "Evaluation of the ulcerogenic effect of potassium chloride by endoscopy and fecal blood loss." J Clin Pharmacol 27 (1987): 206-9

49. Lambert JR, Newman A "Ulceration and stricture of the esophagus due to oral potassium chloride (slow release tablet) therapy." Am J Gastroenterol 73 (1980): 508-11

50. Dietz MW "Iatrogenic jejunal ulcer." Am J Roentgenol Radium Ther Nucl Med 99 (1967): 136-8

51. Barkin JS, Harary AM, Shamblen CE, Lasseter KC "Potassium chloride and gastrointestinal injury." Ann Intern Med 98 (1983): 261-2

52. Sinar DR, Bozymski EM, Blackshear JL "Effects of oral potassium supplements on upper gastrointestinal mucosa: multicenter clinical comparison of three formulations and placebo." Clin Ther 8 (1986): 157-63

53. Strahan J, Sweeney PJ "A case of small bowel perforation." Ulster Med J 34 (1965): 22

54. Brower RA "Jejunal perforation possibly induced by slow-release potassium in a patient with Crohn's disease." Dig Dis Sci 31 (1986): 1387-90

55. Moore JG, Alsop WR, Freston JW, Tolman KG "The effect of oral potassium chloride on upper gastrointestinal mucosa in healthy subjects: healing of lesions despite continuing treatment." Gastrointest Endosc 32 (1986): 210-2

56. Lofgren RP, Rothe PR, Carlson GJ "Jejunal perforation associated with slow-release potassium chloride therapy." South Med J 75 (1982): 1154-5

57. Lubbe WF, Cadogan ES, Kannemeyer AH "Oesophageal ulceration due to slow-release potassium in the presence of left atrial enlargement." N Z Med J 90 (1979): 377-9

58. McMahon FG, Ryan JR, Akdamar K, Ertan A "Effect of potassium chloride supplements on upper gastrointestinal mucosa." Clin Pharmacol Ther 35 (1984): 852-5

59. Riker J, Swanson M, Schweigert B "Esophageal ulceration caused by wax-matrix potassium chloride." West J Med 128 (1978): 542-3

60. Tresadern J, Rickwood AM, Spitz L "Multiple small bowel strictures in a child and accidental potassium chloride ingestion." Br Med J 2 (1977): 1124-5

61. Berg EH, Schuster F, Segal GA "Thiazides with potassium producing intestinal stenosis." Arch Surg 91 (1965): 998-1001

62. Delaney T, Hoxworth PI "Enteric-coated potassium chloride enteropathy." Surg Gynecol Obstet 127 (1968): 76-80

63. Raf LE "Enteric-coated potassium chloride tablets and ulcer of the small intestine." Acta Chir Scand Suppl 374 (1967): 32-50,73-74,76-77

64. Peters JL "Benign oesophageal stricture following oral potassium chloride therapy." Br J Surg 63 (1976): 698-9

65. Svetkey LP, Yarger WE, Feussner JR, DeLong E, Klotman PE "Double-blind, placebo-controlled trial of potassium chloride in the treatment of mild hypertension." Hypertension 9 (1987): 444-50

66. Strom BL, Carson JL, Schinnar R, Sim E, Maislin G, Soper K, Morse ML "Upper gastrointestinal tract bleeding from oral potassium chloride. Comparative risk from microencapsulated vs wax-matrix formulations." Arch Intern Med 147 (1987): 954-7

67. Shuster F, Berg EH "Enteric-coated potassium and bowel obstruction." JAMA 194 (1965): 570

68. Leijonmarck CE, Raf L "Ulceration of the small intestine due to slow-release potassium chloride tablets." Acta Chir Scand 151 (1985): 273-8

69. Hasker W, McCaffrey J "Ulceration of a Meckel's diverticulum due to a potassium chloride tablet." Med J Aust 2 (1972): 261-2

70. Reinus FZ, Weinberger HA, Fischer WW "Medication-induced ulceration of the small bowel." Am J Surg 112 (1966): 97-101

71. Teplick JG, Teplick SK, Ominsky SH, Haskin ME "Esophagitis caused by oral medication." Radiology 134 (1980): 23-5

72. Trewby PN "Drug-induced peptic ulcer and upper gastrointestinal bleeding." Br J Hosp Med 23 (1980): 185-8,190

73. Billig DM, Jordan GL Jr "Nonspecific ulcers of the small intestine." Am J Surg 110 (1965): 745-9

74. Farquharson-Roberts MA, Giddings AE, Nunn AJ "Perforation of small bowel due to slow release potassium chloride (slow-K)." Br Med J 3 (1975): 206

75. Eng J, Sabanathan S "Drug-induced esophagitis." Am J Gastroenterol 86 (1991): 1127-33

76. Sandor F "Complications of "slow-K" therapy." J R Coll Gen Pract 26 (1976): 595-8

77. Wagner W, Longerbeam JK, Smith LL, Feikes HL "Drug-induced ulcers of the small bowel causing intestinal obstruction or perforation." Am Surg 33 (1967): 7-11

78. Barloon TJ, Moore SA, Mitros FA "A case of stenotic obstruction of the jejunum secondary to slow- release potassium." Am J Gastroenterol 81 (1986): 192-4

79. Bronson DL, Gamelli RL "Jejunal ulceration and stricture due to wax-matrix potassium chloride tablets and amitriptyline." J Clin Pharmacol 27 (1987): 788-9

80. Bourke JB, McIllmurray MB, Mead GM, Langman MJ "Drug-associated primary acute pancreatitis." Lancet 1 (1978): 706-8

81. Weiss SM, Rutenberg HL, Paskin DL, Zaren HA "Gut lesions due to slow-release KCI tablets." N Engl J Med 296 (1977): 111-2

82. Hartman SW, Greaney EM Jr, Rottapel D "Small-bowel ulceration due to enteric-coated potassium ingestion in a two-year-old child." Surgery 61 (1967): 814-5

83. McLoughlin JC "Gastrointestinal lesions and potassium chloride supplements." Lancet 1 (1985): 581-2

84. Mason SJ, O'Meara TF "Drug-induced esophagitis." J Clin Gastroenterol 3 (1981): 115-20

85. Moorhouse RA "Letter: Potassium-induced stricture of the small bowel." Lancet 1 (1976): 365

86. Collins FJ, Matthews HR, Baker SE, Strakova JM "Drug-induced oesophageal injury." Br Med J 1 (1979): 1673-6

87. Henry JG, Shinner JJ, Martino JH, Cimino LE "Fatal esophageal and bronchial artery ulceration caused by solid potassium chloride." Pediatr Cardiol 4 (1983): 251-2

88. Emerson DN "Potassium therapy and gastrointestinal lesions." Nebr State Med J 55 (1970): 518-23

89. Williams HP "Accidental subcutaneous infiltration of potassium chloride solution causing necrosis." Br Med J (Clin Res Ed) 289 (1984): 1742

90. Pucino F, Danielson BD, Carlson JD, Strommen GL, Walker PR, Beck CL, Thiege DJ, Gill DS "Patient tolerance to intravenous potassium chloride with and without lidocaine." Drug Intell Clin Pharm 22 (1988): 676-9

91. "Product Information. K-Dur (potassium chloride)." Schering Laboratories, Kenilworth, NJ.

92. Zabala R, Aguirre A, Eizaguirre X, Diaz Perez JL "Contact dermatitis from potassium chloride." Contact Dermatitis 29 (1993): 218-9

93. Watts CD, Curry C, Randolph RP "Intestinal complications found from potassium chloride. Case report." J Natl Med Assoc 57 (1965): 492-3

Not all side effects for Klor-Con / 25 may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

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