Common Side Effects

• The most common side effects of benzodiazepines include drowsiness, decreased ability to concentrate and muscle weakness. When used at night as a treatment for insomnia, grogginess may occur the following morning. Other common side effects include dizziness, blurred vision, nausea and appetite changes.
  
  

Psychomotor Effects

• The sedating properties of benzodiazepines have been shown to slow reaction times and impair spatial visual ability. A 1999 study by the Royal College of Psychiatrists showed an association between benzodiazepine use and road traffic accidents.
  
  

Cognitive Effects

• A meta-analysis, published in the 2004 issue of CNS Drugs, reports that benzodiazepine use may result in an impairment of all areas of cognitive function, including processing speed, memory, visuomotor coordination, verbal learning, concentration and IQ.
  
  

Paradoxical Effects

• A small percentage of benzodiazepine users may experience effects that are in opposition to the intended tranquilizing effects of the drug. Paradoxical effects include aggressive behavior, impulsiveness, depression and suicidal thoughts.
  
  

Addiction

• Benzodiazepines can become highly addictive and induce both a physical and psychological dependence in regular users. A French study, published in the November 2008 La Presse Médicale, found that 23 percent of anxiety patients treated with benzodiazepines had become addicted after three months of use.
  
  

Withdrawal

• According to the Arkansas Geriatric Education Center, abrupt discontinuation of benzodiazepine drugs can lead to withdrawal symptoms as the brain's neurotransmitters return to normal levels. Withdrawal symptoms often include perceptual distortions, tremor, light sensitivity, insomnia, restlessness and agitation.