With the arrival of summer comes a rather less welcome arrival – that of seasonal allergic rhinitis, more commonly known as hay fever. In the UK, an estimated 10-15% of the population are affected, a figure that is also on the rise. Despite the pollens of trees, grasses and weeds being the origin of hay fever, it’s a chemical produced in our bodies that’s actually to blame for the symptoms – and we’ve got the chemicals in medications for hay fever to thank for relief from these symptoms.