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Hay fever: Overview

Created: ; Last Update: July 13, 2017; Next update: 2020.

Introduction

Many children and adults are affected by hay fever in the spring and summer months, when plants grow and bloom. Sneezing and itchy eyes can be a real problem, especially on days that are warm and dry. A lot of people who have allergies and asthma have more asthma attacks around this time of year too.

Hay fever is an allergic reaction to pollen in the air, affecting the upper airways. The symptoms it causes are called allergic rhinitis.

Symptoms

People who have allergic rhinitis sneeze a lot and have a runny or stuffy nose. If their symptoms are more severe, they might also feel weak and tired. Sometimes people have watery and itchy eyes too, and their eyelids become swollen. The medical term for this is allergic rhinoconjunctivitis (allergic rhinitis combined with conjunctivitis). Other possible hay fever symptoms include itching and asthma-like symptoms such as coughing, wheezing, and shortness of breath.

These symptoms only occur during the pollen season. They are usually much more noticeable than the symptoms of a dust mite allergy, but don't last the whole year.

Causes

Allergy symptoms arise when your body overreacts to particular substances that are usually harmless, such as pollen. These substances (allergens) trigger a chain reaction in the immune system. First, antibodies to the allergen are made, and they bind to specific cells. If these cells come into contact with the allergen again, they are then able to release chemical substances, one of which is histamine. These substances then lead to allergic reactions such as sneezing or itchy eyes.

The following table shows which plants commonly cause allergic reactions and when pollen from those plants is typically in the air:

Plant Pollen season
Hazel tree February
Alder tree March
Birch tree April
Beech tree May
Oak tree May
Ash tree Mid-April to mid-May
Grasses Mid-May to mid-August
Mugwort Mid-July to late August
Ragweed September

Risk factors

Sometimes a higher risk of allergies runs in families. Environmental factors such as air pollution and cigarette smoke can make allergies more likely.

Allergies are quite common nowadays. This may be partly due to higher standards of hygiene and the fact that some infections have become less common in childhood. As a result, our immune systems are often not as “well trained” as they might have been in the past.

Prevalence and outlook

Hay fever affects about 1 out of 4 people in industrialized countries like Germany. It usually first arises before the age of 20.

The allergic rhinitis symptoms may "move down" into the lungs and develop into allergic asthma after several years. Sometimes people who are allergic to pollen, for instance, become allergic to certain foods too after a while. This is known as cross-reactivity.

Severe hay fever may increase the likelihood of developing other medical conditions such as sinusitis (inflammation of the sinuses). Hay fever makes the mucous membranes overly sensitive in a lot of people too. As a result, their nose also reacts more strongly to irritants like dry air in heated rooms or cigarette smoke.

Diagnosis

If you see a doctor, you will first be asked about your symptoms, your everyday life circumstances, and medical history. The doctor can then do a skin prick test to find out whether you are allergic to particular substances. This involves placing small drops of various potential allergens on the skin of your forearm, leaving enough space between them, and then pricking the surface of your skin where the allergens are, so the substances go into the skin. If your skin becomes red and swollen, like a big mosquito bite, it’s a sign that you’re allergic to that substance.

You might also need a blood test or something known as a nasal provocation test. This is where the membranes lining the nose are exposed to extracts of the potential allergen using a nasal spray or drops. If the lining of your nose becomes swollen, you sneeze and your nose starts running, you are likely to have an allergy.

Prevention

It's nearly impossible to protect yourself from pollen, unless you travel to areas of the world where there is currently no pollen in the air. You can minimize the effects of pollen by keeping windows closed and washing your hair before going to bed. Local weather reports often provide information about pollen forecasts and current pollen counts.

Treatment

Various medications are available to treat the symptoms:

  • Antihistamines
  • Steroids (corticosteroids)
  • Chromones (mast cell stabilizers)
  • Leukotriene receptor antagonists
  • Decongestant nasal drops and sprays

There are also non-drug alternatives such as saline (salt water) nasal sprays and nasal washes (nasal irrigation).

Allergen-specific immunotherapy (also known as desensitization) can reduce your sensitivity to allergens over the long term. Like with vaccines, this treatment approach involves being exposed to small amounts of the substance by having it injected or placing it under your tongue. In allergen-specific immunotherapy, you are exposed to the allergen at regular intervals. The treatment takes about three years to complete.

Sources

  • Biedermann T, Heppt W, Renz H, Röcken M (Ed). Allergologie. Berlin: Springer; 2016.
  • Brozek JL, Bousquet J, Baena-Cagnani CE, Bonini S, Canonica GW, Casale TB et al. Allergic Rhinitis and its Impact on Asthma (ARIA) guidelines: 2010 revision. J Allergy Clin Immunol 2010; 126(3): 466-476. [PubMed: 20816182]
  • Greiner AN, Hellings PW, Rotiroti G, Scadding GK. Allergic rhinitis. Lancet 2011; 378(9809): 2112-2122. [PubMed: 21783242]
  • Trautmann A, Kleine-Tebbe J. Allergologie in Klinik und Praxis. Stuttgart: Thieme; 2013.
  • IQWiG health information is written with the aim of helping people understand the advantages and disadvantages of the main treatment options and health care services.

    Because IQWiG is a German institute, some of the information provided here is specific to the German health care system. The suitability of any of the described options in an individual case can be determined by talking to a doctor. We do not offer individual consultations.

    Our information is based on the results of good-quality studies. It is written by a team of health care professionals, scientists and editors, and reviewed by external experts. You can find a detailed description of how our health information is produced and updated in our methods.

© IQWiG (Institute for Quality and Efficiency in Health Care)
Bookshelf ID: NBK279488

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