Can penicillin (antibiotic) cause ataxia?

Penicillin and Ataxia: Neurological Adverse Effects

Penicillin does not commonly cause ataxia as an adverse effect, though rare neurological reactions can occur, particularly in patients with renal dysfunction, underlying brain abnormalities, or when administered in high doses. 1

Neurological Adverse Effects of Penicillin

• Penicillin can cause various hypersensitivity reactions ranging from mild skin eruptions to fatal anaphylaxis, but neurological adverse effects are relatively uncommon 2

• The FDA drug label for penicillin mentions neuropathy as an infrequent reaction, usually associated with high doses of parenteral (injectable) penicillin rather than oral formulations 2

• When neurological adverse effects do occur with β-lactam antibiotics (including penicillins), they typically manifest as seizures rather than ataxia, particularly in predisposed individuals 1

Risk Factors for Neurological Complications

• Renal dysfunction significantly increases the risk of neurological adverse effects from β-lactam antibiotics, as decreased clearance leads to drug accumulation 3

• Underlying brain abnormalities or pre-existing neurological conditions increase susceptibility to antibiotic-induced neurological effects 3

• High doses of penicillin, particularly when administered intravenously, pose a greater risk for neurological complications 1

• Patients with a history of epilepsy or seizures may be more vulnerable to antibiotic-induced neurological effects 1

Clinical Considerations

• While ataxia specifically is not commonly reported with penicillin, other β-lactam antibiotics like ceftazidime and cefepime are more frequently associated with abnormal movements and neurological manifestations 3

• If a patient develops neurological symptoms while on penicillin therapy, consider:

  • Checking renal function 3
  • Evaluating for drug interactions, particularly with antiepileptic medications 4
  • Assessing for signs of hypersensitivity reactions 2
  • Considering alternative antibiotics if symptoms persist 3

• Metronidazole, rather than penicillin, has been more clearly documented to cause cerebellar ataxia, particularly with prolonged use 5

Management of Suspected Neurological Adverse Effects

• If ataxia or other neurological symptoms develop during penicillin therapy, immediate discontinuation of the antibiotic should be considered 3

• For patients requiring continued antibiotic therapy, switching to a different class of antibiotics with lower neurological risk profile may be necessary 3

• Close monitoring of drug levels is recommended when administering β-lactam antibiotics to patients with risk factors for neurological complications 1

• In cases of altered consciousness that might be related to antibiotic therapy, EEG monitoring should be considered as many antibiotic-related seizures may be non-convulsive 1

Penicillin Allergy Considerations

• While not directly related to ataxia, it's worth noting that penicillin is the most common cause of drug-induced anaphylaxis, which can have neurological manifestations 6

• Only 1.6-6% of patients with reported penicillin allergy actually have confirmed allergy when tested 6

• Severe allergic reactions to penicillin occur in approximately 0.04-0.015% of treated patients, with anaphylaxis occurring in about 0.001% 6