Antihistamines driving performance

The effect of levocetirizine 5 mg/day on actual driving performance during normal traffic has been compared with the effect of the first-generation antihistamine diphenhydramine 50 mg/day in 48 healthy volunteers in a double-blind, placebo-controlled, randomized trial (73). Treatments were given on days 1, 2, 3, and 4, at 90 minutes before the start of a standardized driving test on days 1 and 4. In contrast to diphenhydramine, driving performance was not significantly affected by levocetirizine 5 mg/day. 

O Hanlon JF, Ramaekers JG. Antihistamine effects on actual driving performance in a standard test a summary of Dutch experience, 1989-94. Allergy 1995 50(3) 234-42. 

One class of antidepressants that has yielded consistent findings is antihistamines. While most early antihistamines (known as 1 generation) had been shown to impair driving related skills, a review of 130 experimental studies revealed that only one fifth of them found impaired performance with 2" generation antihistamines, Mid only ten percent of the studies that evaluated actual driving performance obtained drug-related impairments (Moskowitz and Wilkinson, 2003). 

Faxative abuse in elderly patients results in abdominal pain, as well as fluid and electrolyte imbalance. The chronic misuse of analogs containing large amounts of caffeine may produce rebound headache. Antihistamines may cause sedation and drowsiness, and it is advised that patients do not drive after taking antihistamines. People who are involved in performing skilled jobs should restrict their use of antihistamines and sedatives.99,100... 

The concurrent use of small or moderate amounts of alcohol and therapeutic doses of drugs that are CNS depressants can increase drowsiness and reduce alertness. These drugs include antidepressants, antiemetics, antiepileptics, antihistamines, antipsychotics, anxiolytics, barbiturates, hypnotics, opioid analgesics, skeletal muscle relaxants, and others. This increases the risk of accident when driving or handling other potentially dangerous machinery, and may make the performance of everyday tasks more difficult and hazardous. 

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