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Over-Counter Allergy Medications Can Impair Driving

Apr 25, 2002 | WCVB

It is allergy season and many people use over-the-counter allergy medications for relief, but the drugs contain powerful substances which can make many people sleepy.

NewsCenter 5's medical editor Dr. Timothy Johnson reported that the antihistamines in allergy medicines can be very sedating. He said an Iowa study done a few years ago showed the drugs can cause more driving impairment than alcohol.

He said he conducted his own demonstration, which was not a scientific study, but he said it did raise some alarms.

"I feel really tired and a little bit spacy. Disconnected a little bit. And my eyes, I feel like I should have some tape holding them up," said one test subject.

In order to get an idea of how such studies are done, five Boston-area women were invited to the Virtual Environments Lab at Northeastern University.

The director, Dr. Ronald Morant, set up a driving simulation that allowed subjects to operate a vehicle as if they were driving on typical American streets and roads.

Two-to-three hours before their driving simulation, each woman had taken a standard dose of anthihistimine as contained in a popular allergy medicine. All of them acknowledged feeling drowsy from the medicine before they tried driving. And all of them realized that this was not a definitive study, but a way for us to demonstrate potential problems.

Three of the women behind a simulator wheel had a hard time concentrating on the road.

"I definitely feel a little disconnected from the road," one said.

The next woman to climb into the car couldn't stay in her lane. She was asked if she felt a different because of the medication and said that she felt she was a danger on the road and wouldn't be wanting to drive her young children under such circumstances.

The lanes were the least of her problems. She couldn't follow simple directions either. All of the drivers stopped too early at the stop signs. It's not a major issue in a simulation, but on a real road might cause major accidents.

After the simulation, all the women said they were definitely affected by the medications.

"My reflexes were slow, very slow. It was very difficult to turn," said one.

"I would never have gotten in a car to drive with the way I felt," said another.

Dr. Morant said he noticed some differences in the test subjects compared to drivers he has tested who have not taken antihistamines.

"They were aware that they had problems and they tried to compensate by driving slower and being more cautious," he said.

Johnson said the names of some of the over-the-counter antihistamine ingredients that cause drowsiness are:




Most of the medications have clear warnings on the packaging that tells consumers not to drive or operate heavy machinery when they take the drugs.

There are new-generation, prescription antihistamines that can be purchased which are non-sedating, such as Claritin, Zyrtec and Allegra.

Drowsiness is not the only indication of impairment, because many users often do not think they are drowsy or impaired.

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