adverse effects of benzodiazepines

Last reviewed 01/2018

Both anxiolytic and hypnotic benzodiazepines worsen motor skills, attention and memory. Some short and long term adverse effects of benzodiazepines include:

  • oversedation -
    • the most common dose related unwanted side effect
    • symptoms include drowsiness, poor concentration, incoordination, muscle weakness, dizziness and mental confusion
    • patients should be warned that they may feel slightly sedated at the start of the treatment (especially immediately after their dose) and this will diminish after a couple weeks of treatment
    • this is more prominent and persists for a long time  in the elderly and may result in falls and fractures
    • people who are driving or operating machinery should be warned about accidents due to this adverse effect
  • drug interaction
    • patients taking benzodiazepines should be warned about interaction with the following drugs
      • some antidepressants e.g. amitriptyline
      • major tranquillisers or neuroleptics e.g. prochlorperazine, trifluoperazine 
      • anticonvulsants e.g. phenobarbital, phenytoin, carbamazepine
      • sedative antihistamines e.g. diphenhydramine, promethazine
      • opiates (heroin, morphine, meperidine)
      • alcohol
  • memory impairment
    • there is impaired acquisition of new information
    • impairment of “episodic memory” - remembering recent events, when they occurred and their sequence in time may be deficient
    • other features of memory such as memory for words, ability to remember a telephone number for a few seconds, and recall of long-term memories are not affected
  • paradoxical stimulant effect
    • may cause increased anxiety, insomnia, nightmares, hallucinations at the onset of sleep, irritability, hyperactive or aggressive behaviour, and exacerbation of seizures in epileptics
    • frequently seen in anxious and aggressive individuals, children, and the elderly
    • paradoxical reactions are more prone in patients on benzodiazepine who use alcohol
  • depression
    • usually appears after prolonged benzodiazepine use
    • patients often complain of “emotional blunting”  - inability to feel normal pleasure or pain due to inhibition of arousal
  • adverse effects in the elderly
    • older people are more susceptible to the central nervous system depressant effects of the drug when compared to the younger people
    • may cause - confusion, night wandering, amnesia, ataxia, hangover effects and "pseudodementia" (erroneously diagnosed as Alzheimer’s disease)
  • adverse effects in pregnancy
    • since benzodiazepine cross the placenta, even therapeutic dosages at late stages of pregnancy may result in neonatal complications
  • dependence -
    • benzodiazepines are considered to be addictive drugs 
    • both psychological and physical dependence may occur within a few weeks or months of regular or repeated use  

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