The good weather at the weekend has led to a sharp rise in work absences as 32,000 extra employees are badly hit by hay fever.
Absence is up almost 4% against seasonal expectations with unusually high levels attributed to allergies.
On Monday, absences due to allergies increased by over 320%.
Aaron Ross, managing director of FirstCare, the UK's largest absence management provider, said: "The pollen count rose sharply at the weekend as the wet weather made way for dry heat. Despite a number of warnings from weather forecasters, many people appear to have been caught off guard and are now rushing out to see their pharmacist for medication."
He added: "In addition to a number of over-the-counter remedies, there are also a number of precautions people can take to reduce the impact of hay fever.
"We have put together a five-point guide for clients and their employees, to ensure that as many people as possible can enjoy the good weather this summer."
The guide includes avoiding going outside on evenings and mornings when pollen is worse, washing hair before bed to remove the pollen and eating locally sourced honey. According to experts, eating honey that has been locally produced will increase tolerance and improve immunity to local pollen.