Skip to main content

Mezlocillin Side Effects

Applies to mezlocillin: injectable powder for injection.


Mezlocillin is generally well-tolerated.[Ref]


Hypersensitivity reactions are usually mild. General skin reactions and eosinophilia occur in up to 3% of treated patients. As with other penicillins, hypersensitivity reactions may include urticarial rash, angioedema, pruritus, and, in rare cases, bronchospasm, hypotension, and anaphylaxis.[Ref]

Rare cases of interstitial nephritis related to mezlocillin are likely due to hypersensitivity. Intravenous administration may result in thrombophlebitis or vein irritation in rare cases.

One small study demonstrated an increased incidence of allergic reactions in patients with cystic fibrosis who were given mezlocillin.[Ref]


Gastrointestinal side effects are among the most common adverse effects, with diarrhea occurring in up to 3% of patients.[Ref]

Nausea, vomiting, and altered sensation of taste have been reported. Mild and transient elevations of liver function tests are rare. A rare case of cholestatic jaundice associated with mezlocillin has been reported.[Ref]


Elevations of BUN and serum creatinine have been reported, but may be related to underlying illness. Interstitial nephritis has been reported in rare cases.[Ref]

Mezlocillin may cause a false positive sulfosalicylic acid test for proteinuria.[Ref]


Hematologic side effects are uncommon. Leukopenia has been reported in less than 1% of patients. Leukopenia has been reported in 23% of patients with liver disease receiving beta-lactam antibiotics. Platelet dysfunction may occur in up to 25% of treated patients resulting in significantly prolonged bleeding times.[Ref]

Agranulocytosis and nonhemolytic Coombs' positive tests have been reported. In vitro studies show mezlocillin to cause decreased platelet aggregation, but no clinical bleeding has been observed.[Ref]

Nervous system

Although not reported with mezlocillin, convulsions and neuromuscular hyperirritability may be potential side effects of penicillin derivatives.[Ref]


Rare cases of hypokalemia have been reported, but may have been due to factors other than mezlocillin therapy.[Ref]

Rare cases of hypokalemia have been reported, but may have been due to factors other than mezlocillin therapy.[Ref]


1. "Multum Information Services, Inc. Expert Review Panel"

2. Pancoast SJ, Jahre JA, Neu HC (1978) "Mezlocillin in the therapy of serious infections." Am J Med, 67, p. 747-52

3. Russo J, Russo ME (1982) "Comparative review of two new wide-spectrum penicillins: mezlocillin and piperacillin." Clin Pharm, 1, p. 207-16

4. Konopka (1982) "Clinical experience with mezlocillin in Europe: an overview." J Antimicrob Chemother, 9, p. 1-6

5. Parry MF, Neu HC (1982) "The safety and tolerance of mezlocillin." J Antimicrob Chemother, 9, p. 1-8

6. Cushner HM, Copley JB, Bauman J, Hill SC (1985) "Acute interstital nephritis associated with mezlocillin, nafcillin, and gentamicin treatment for pseudomonas infection." Arch Intern Med, 145, p. 1204-7

7. Palla R, Panichi V, Bionda A, et al. (1986) "Acute renal failure after mezlocilline." Clin Nephrol, 25, p. 315-6

8. Gerecht WB, Henry NK, Hoffman WW, et al. (1989) "Prospective randomized comparison of mezlocillin therapy alone with combined ampicillin and gentamicin therapy for patients with cholangitis." Arch Intern Med, 149, p. 1279-84

9. Burks JH, Fliegelman R, Sokalski SJ (1989) "An unforeseen complication of home parenteral antibiotic therapy." Arch Intern Med, 149, p. 1603-4

10. Pleasants RA, Walker TR, Samuelson WM (1994) "Allergic reactions to parenteral beta-lactam antibiotics in patients with cystic fibrosis." Chest, 106, p. 1124-8

11. Peters HJ (1986) "Comparison of intravenous ciprofloxacin and mezlocillin in treatment of complicated urinary tract infection." Eur J Clin Microbiol, 5, p. 253-5

12. Decker CF, Martin GJ, Barham WB, Paparello SF (1992) "Severe cholestatic jaundice caused by mezlocillin." Clin Infect Dis, 15, p. 179-80

13. Kirkwood CF, Lasezkay GM (1985) "Neutropenia associated with mezlocillin and piperacillin." Drug Intell Clin Pharm, 19, p. 112-4

14. Fass RJ, Copelan EA, Brandt JT, Moeschberger ML, Ashton JJ (1987) "Platelet-mediated bleeding caused by broad-spectrum penicillins." J Infect Dis, 155, p. 1242-8

15. Mehta P, Lawson D, Gross S, Graham-Pole J (1989) "Comparative effects of mezlocillin and carbenicillin on platelet function and thromboxane generation in patients with cancer." Am J Pediatr Hematol Oncol, 11, p. 286-91

16. Singh N, Yu VL, Mieles LA, Wagener MM (1993) "Beta-lactam antibiotic-induced leukopenia in severe hepatic dysfunction: risk factors and implications for dosing in patients with liver disease." Am J Med, 94, p. 251-6

17. Gharpure V, Oconnell B, Schiffer CA (1993) "Mezlocillin-induced thrombocytopenia." Ann Intern Med, 119, p. 862

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.