Meropenem Side Effects
Meropenem is generally well-tolerated with a favorable safety profile, but the most common side effects include diarrhea (4.8%), nausea/vomiting (3.6%), headache (2.3%), and rash (1.9%), with serious but rare complications including seizures, thrombocytopenia (particularly in renal impairment), and drug-induced liver injury 1.
Common Side Effects (>1% incidence)
Based on FDA labeling from clinical trials of 2,904 adult patients 1:
Local reactions:
- Inflammation at injection site (2.4%)
- Injection site reactions (0.9%)
- Phlebitis/thrombophlebitis (0.8%)
- Pain at injection site (0.4%)
Systemic reactions:
- Diarrhea (4.8%)
- Nausea/vomiting (3.6%)
- Headache (2.3%)
- Rash (1.9%)
- Constipation (1.4%)
- Pruritus (1.2%)
Serious Adverse Effects Requiring Vigilance
Neurological Toxicity
Meropenem has relatively low pro-convulsive activity (16 compared to penicillin G = 100), but seizures and neurological complications can occur, especially with high doses or renal impairment 2. Neurological manifestations include:
- Seizures (0.07% in non-meningitis infections) 3
- Delirium and confusion
- Encephalopathy
- Myoclonus
- Headaches and paresthesias 1
The risk increases when free meropenem concentrations exceed 8 times the MIC, with trough levels above 64 mg/L associated with 50% risk of neurotoxicity 2. Renal failure is the primary risk factor for neurotoxicity due to drug accumulation 2.
Thrombocytopenia
Thrombocytopenia occurs particularly in patients with renal impairment and was identified as a major problem in 37.81% of cases in one study 4. This typically develops after 7 days of therapy 5. The FDA label specifically warns about increased thrombocytopenia risk in patients with moderately severe renal impairment (creatinine clearance 10-26 mL/min) 1.
Hepatotoxicity
Drug-induced liver injury (DILI) can occur, presenting as either cholestatic or mixed hepatocellular/cholestatic patterns 6, 7. Key features:
- Can develop within 48 hours to 6 days of starting therapy 6, 7
- Presents with elevated transaminases (ALT up to 1160 U/L), alkaline phosphatase (up to 1450 U/L) 6, 7
- May include mild pruritus and generalized weakness 6
- Resolves upon drug discontinuation 6, 7
Hypersensitivity Reactions
- Urticaria and maculopapular rash with petechiae 5
- Severe cutaneous adverse reactions (rare) 1
- Anaphylaxis (rare)
Special Population Considerations
Renal Impairment
Dose adjustment is mandatory for creatinine clearance ≤50 mL/min 1. Patients with renal impairment experience:
- Increased risk of seizures, heart failure, kidney failure, and shock 1
- Higher prevalence of side effects, particularly thrombocytopenia 4
- Decreased generalized health status 4
Elderly Patients
No overall differences in safety compared to younger patients, but greater sensitivity possible due to age-related decline in renal function 1.
Pediatric Patients
Safety profile similar to adults, with diarrhea, rash, and oral moniliasis being most common 1. Over 1,000 pediatric patients studied with favorable outcomes 3.
Less Common but Notable Side Effects (<1% incidence)
Bleeding events:
- GI hemorrhage (0.5%)
- Melena (0.3%)
- Epistaxis (0.2%)
Other systemic effects:
- Oral and vaginal candidiasis
- Clostridioides difficile-associated diarrhea 1
- Cholestatic jaundice/hepatic failure (rare) 1
Laboratory Abnormalities
- Elevated liver enzymes (ALT, AST, alkaline phosphatase, LDH, bilirubin)
- Thrombocytopenia or thrombocytosis
- Eosinophilia
- Elevated creatinine and BUN 1
Critical Monitoring Recommendations
Monitor liver function tests routinely, especially in elderly patients receiving meropenem 6. Watch for unexplained neurological manifestations in all patients, particularly those with renal impairment, and consider temporary drug suspension if they occur 2. Advise outpatients not to operate machinery or vehicles until tolerance is established 1.
Overdose
Overdose may cause ataxia, dyspnea, and convulsions. Adverse events are generally mild and resolve with dose reduction or discontinuation. Meropenem is dialyzable 1.