Motorists are being warned about the dangers of driving under the influence of hay fever drugs.
One in seven drivers who suffer from hay fever said they never read the leaflet advice before taking medication.
But hay fever tablets are known to cause drowsiness and even blurred vision.
Hay fever remedies can also contain several different types of medication.
As the pollen levels rise, drivers are being urged to always check the label before they get behind the wheel.
Matt Lloyd, motoring expert from Confused.com, who carried out the research, said: "As Hay fever is in full bloom across the UK, many people may be taking prescription and over-the-counter drugs to relieve thesymptoms.
"However, many Brits are unaware that these drugs could have an effect on people's driving ability.
"Before taking any medication, motorists must always read the safety leaflet before driving.
"Or if unsure they should ask the pharmacist or err on the side of caution and don't drive, as road safety and the safety of others should be a top priority for any driver."
A new drug-driving offence came into force last year which includes some prescription medication and a number of over-the-counter medicines.
Anyone convicted of being over the specified limit and driving with certain drugs in their system could be fined £5,000, given a six-month prison sentence and a minimum one-year driving ban.
What drugs are included and what are the limits?