Many people find their hay fever symptoms dwindle as they age, although no one knows why. But allergies can and do get worse over a lifetime, and there are reports of people who are middle aged and older suddenly developing hay fever having never been sensitive to pollen before.
It's also true that if you're unfortunate enough to have one allergy, you are more likely to develop others. This is in part down to basic biology: some people simply have an immune system that is more allergy-prone. "If you've got an allergy, you've got that combination of genetic susceptibility plus environmental exposure, and it's that combination that produces an allergy," says El-Shanawany.
Not only that, immune cells sensitised to one allergen can cross-react with other related proteins, meaning allergies can "spread". For instance, some of ...
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