There is little doubt within the medical profession that the number of allergies in the UK is increasing.
Research published in 2007 showed the number of hospital admissions for food allergies had increased by 500% since 1990.
Meanwhile, cases of hay fever, asthma and eczema have been rising for three decades, meaning as many as one in three people are thought to be affected by an allergy at some point in their lives, according to the charity Allergy UK.
This has led to the National Institute for Health and Clinical Excellence publishing guidelines on how to deal with allergies in children.
Dr Adam Fox, from Guy's and St Thomas's Hospital, who helped write the guidelines, says: "As this is a new pattern of disease, some GPs have found it hard to get up to speed with all of the skills they need to accurately assess children."
Allergic reactions come from the immune system reacting to harmless substances as if they were a threat to the body.
Symptoms can include sneezing, skin rashes and potentially life-threatening anaphylactic reactions.
But why are the number of cases increasing? Dr Fox says there is no easy answer: "There are lots of theories, unfortunately lots of them have holes in them and we don't really know the answer."
As Dr Fox suggests, the truth is there is no all-encompassing piece of research which says "the rise in allergies is as a result of ..."
The House of Lords Science and Technology Committee reviewed the evidence in 2007 after speaking to a several specialists. Their report suggested that the following could contribute to allergies:
- Hygiene theory - Living cleaner lifestyles means the immune system has fewer germs to deal with and over reacts when it comes into contact with harmless substances
- Mother's diet - Pregnancy and breastfeeding could offer protection against allergies
- Allergen exposure - Higher exposure to substances which provoke an immune reaction
- Atmospheric pollution - Chemicals in the air provoking an immune response
Whatever the reasons, the GP remains the first point of call for a suspected allergy.
The new guidelines for England and Wales give detailed advice about how to recognise symptoms and when to refer to specialists.
Diagnosing an allergy can include eliminating foods which are suspected of causing a reaction and reintroducing them later or by doing a blood test which searches for the antibodies produced in reaction to a substance.
If this does not work then patients can be referred on to a specialist. The British Society for Allergy and Clinical Immunology lists more than 90 NHS allergy specialist centres in the UK.
But Allergy UK says this is not enough. It wants doctors to set up specialist allergy services within their surgeries to make sure parents concerned about allergic reactions are given more time than in a standard GP appointment.