Abstract
Thirty years after the first reported case of cephalexininduced psychosis [1], we report a similar event in a woman with no comorbid chronic disease. Cephalexin remains a commonly used antibiotic, with indications as documented in infection treatment guidelines [2].
A 37-year-old mother was referred to Mental Health Services by her general practitioner following the development of psychotic symptoms after cephalexin treatment for ‘pneumonia’. She was seen in our specialized GP Liaison Outpatient Service. After 2 days of cephalexin treatment (500 mg qid), she developed a generalized rash and experienced distressing abnormal perceptual experiences. She described:
visual hallucinations with distortions of form and shape of objects, altered taste, altered smell, faint auditory hallucinations, somatic hallucinations with an altered sense of her body, especially her head which felt ‘hollow’.
She felt very unwell but did not seek medical help, although ceased cephalexin. She took 10 mg of diazepam and slept for the next 24 h. The symptoms gradually resolved over the following 2 weeks. Her symptoms reminded her of LSD-induced hallucinatory experiences.
The patient was previously well, married and in parttime employment. She had a long history of mild depressive symptoms associated with psychosocial stressors, but she had never sought treatment. There was no recent substance or alcohol abuse and she did not smoke. She had a history of brief but heavy LSD use 20 years earlier, when she had taken 60 trips over 1 year, but none since. There was no family history of mental illness.
It seems probable this woman experienced an acute reversible psychosis after cephalexin. Since the first report [1] there have been two similar reports with other cephalosporins [3, 4]. Four cases of psychotic events have been reported to ADRAC after treatment with cephalexin (pers. comm.). It is of interest that in contrast to the other case reports, this patient had no physical comorbidity.
While psychosis is an unusual side-effect of cephalexin, it is important to recognize the aetiology of such a distressing experience and withdraw the antibiotic immediately.