Omnipen Side Effects
Generic name: ampicillin
Medically reviewed by Drugs.com. Last updated on Feb 2, 2022.
Note: This document contains side effect information about ampicillin. Some of the dosage forms listed on this page may not apply to the brand name Omnipen.
For the Consumer
Applies to ampicillin: oral capsules, oral for suspension, parenteral powder for injection or infusion
Side effects include:
For Healthcare Professionals
Applies to ampicillin: compounding powder, injectable powder for injection, oral capsule, oral powder for reconstitution
Very common (10% or more): Rash, pruritus, exanthema, itching
Common (1% to 10%): Morbilliform rash
Frequency not reported: Erythematous maculopapular rash (including mildly pruritic), macular rash, purpura, maculopapular rash, skin reactions (e.g., erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis), other skin rashes, erythematous eruptions, acute generalized exanthematous pustulosis[Ref]
Frequency not reported: Oral candidiasis/moniliasis, black hairy tongue, Clostridium difficile-associated diarrhea, hemorrhagic colitis, sore mouth/tongue, pancreatitis, gastritis, generalized abdominal cramps[Ref]
Glossitis, stomatitis, black hairy tongue, nausea, vomiting, enterocolitis, pseudomembranous colitis, and diarrhea were typically associated with oral formulations.
Acute pancreatitis has been reported and confirmed by rechallenge with this drug in a patient in whom there was no other obvious cause of pancreatitis.[Ref]
Common (1% to 10%): Localized phlebitis
Frequency not reported: Phlebitis at IV administration site, pain at IM administration site[Ref]
Common (1% to 10%): Swelling and pain, exanthema and enanthem in the oral region
Uncommon (0.1% to 1%): Infection with fungi/resistant bacteria (especially during prolonged and/or repeated use), drug fever
Frequency not reported: Fever (including high fever)[Ref]
Uncommon (0.1% to 1%): Serious allergic reactions (e.g., serum sickness, allergic nephritis)
Rare (0.01% to 0.1%): Life-threatening anaphylactic shock
Frequency not reported: Anaphylaxis, serum sickness-like reactions, hypersensitivity reactions (including urticarial rash, erythema multiforme, exfoliative dermatitis, edema, hypotension, fever, eosinophilia, dyspnea, interstitial nephritis, Henoch-Schonlein purpura, focal glomerulonephritis, Stevens-Johnson syndrome, bullous pemphigoid, hypersensitivity myocarditis, toxic epidermal necrolysis, fixed drug eruptions)[Ref]
Anemia, thrombocytopenia, hemolytic anemia, thrombocytopenic purpura, eosinophilia, leukopenia, and agranulocytosis have been reported during treatment with penicillins. In general, these reactions were reversible after stopping therapy and were believed to be sensitivity reactions.
Neutropenia was described in a case report of 3 pediatric patients who received high doses (150 to 400 mg/kg) of this drug IV. In all 3 cases, white blood cell and neutrophil counts returned to normal after discontinuation of therapy.[Ref]
Seizures have been reported with renal dysfunction or at very high IV doses.
Seizures have been reported in patients with high serum drug levels, although these patients were otherwise very ill. High cerebral spinal fluid (CSF) levels of some penicillins were known to be potentially neurotoxic, and the CSF level of this drug increased significantly in meningitis.
Generalized seizures have been described in 2 patients during use of this drug, although in both cases, there were underlying disease factors that may have predisposed the patients to seizure activity.
Encephalopathy has occurred when blood drug level reached 800 mg/L.
Toxic symptoms (e.g., drowsiness, hyperreflexia, myoclonic twitches, convulsions, coma) have occurred at lower drug levels in patients with meningitis; the blood-brain barrier became more permeable in meningitis.[Ref]
Uncommon (0.1% to 1%): Acute interstitial nephritis
Very rare (less than 0.01%): Acute renal failure with excretion of urine crystals
Frequency not reported: Interstitial nephritis, nephropathy, glomerulonephritis[Ref]
Mild, temporary elevation in AST reported in patients who received larger (2 to 4 times) and more frequent IM injections than usual. Evidence indicated AST was released at IM injection sites for this drug and increased AST did not necessarily indicate liver involvement.[Ref]
Uncommon (0.1% to 1%): Transaminase elevation
Crystalluria has been reported with high-dose IV administration.[Ref]
Uncommon (0.1% to 1%): Crystalluria
Uncommon (0.1% to 1%): Laryngeal edema
Frequency not reported: Laryngeal stridor[Ref]
Frequency not reported: Arthralgia
Frequency not reported: Anorexia
More about Omnipen (ampicillin)
- Drug interactions
- Dosage information
- During pregnancy or Breastfeeding
- Drug images
- Drug class: aminopenicillins
Related treatment guides
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Some side effects may not be reported. You may report them to the FDA.