What is hay fever?
Hay fever is an allergic condition in which the body's immune system overreacts to pollen and other substances that are otherwise harmless. The substances to which people are allergic are referred to as allergens.
Hay fever is also known as seasonal allergic rhinitis (irritation and inflammation of the nasal lining). As the word seasonal suggests, the allergy usually occurs at specific times of the year. Most people suffer from symptoms in the spring, summer or autumn, depending on the cause of their allergy.
There is a genetic predisposition to hay fever and allergies. The allergy tends to become active when a person has been exposed to the same irritant a number of times.
What are the symptoms of hay fever?
The main symptoms of hay fever are a runny nose, nasal congestion (blocked nose), sneezing, coughing, itching of the nose and eyes, and watery eyes. Loss of smell is common and can affect the sense of taste. The eyes can become red and swollen causing difficulties with many activities. For people with extreme allergies, the symptoms may be severe enough to prevent them sleeping properly.
The symptoms usually occur at specific times each year - many people start to suffer symptoms in the spring because of pollen in the air from spring flowers and trees.
What are the causes of hay fever?
In most cases, hay fever is caused by an allergy to pollen from flowers, trees or grasses. Although pollen itself is not a harmful substance the immune systems of people with hay fever react as if it is. In these people contact with pollen (or other allergen) causes their body to produce excessive amounts of a substance called histamine - this leads to inflammation of the mucous membranes that line the eyes, nose and air passages. Many people are allergic to more than one substance. Moulds may also act as an allergen.
Ideally, knowing the exact substance that is causing their allergy should allow sufferers to avoid contact with that substance. However, this is often impossible, particularly if the allergen is pollen in the air.
Allergies in children may change and develop with age as they become more exposed to other irritants.
Are any tests to confirm a diagnosis of hay fever?
Skin testing can be used to identify allergies to different substances. Once the allergen is known the hay fever sufferer can then try to minimise their exposure to it where possible.
One type of skin test involves small amounts of different solutions of pollens and allergens from various sources being placed on the skin. The skin is then pricked to allow the solution to enter under the skin surface. This test causes minimal discomfort and is suitable for children. Redness and swelling will occur if there is an allergy to a substance.
A blood test known as a radioallergosorbent test (RAST) may also be used. A blood sample is taken and then sent to a lab where it is tested for evidence of sensitivity to possible allergens.
Keeping a history of allergic reactions can also be useful as some reactions happen immediately on exposure to an irritant substance. However, other reactions may occur up to 24 hours later making the cause harder to identify.
What treatment is available?
As mentioned above, avoiding the allergen(s) is the best way to prevent symptoms of hay fever, but in reality this is often not possible. Practical measures such as avoiding fresh cut grass, and closing windows may help.
The most common medical treatment for hay fever is an antihistamine. These medicines do not prevent the allergic reaction from occurring but block the body's reaction to the excess histamine produced. Some antihistamines may cause dry mouth and sleepiness in some people but newer types do not have these side effects.
Some antihistamines are available only on prescription but some can be purchased over the counter from a pharmacist. Most preparations are available as tablets but some are also available in syrup form.
Sedating antihistamines include alimemazine, chlorphenamine (eg, Piriton®), clemastine (Tavegil®), cyproheptadine (Periactin®), hydroxyzine (eg, Atarax®), ketotifen (Zaditen®) and promethazine (Phenergan®).
Non-sedating antihistamines include acrivastine (Benadryl Allergy Relief®) bilastine (Ilaxten®), cetirizine (eg, Benadryl Allergy Liquid Release®, Zirtek®), desloratadine (eg, Neoclarityn®), fexofenadine (Telfast®), levocetirizine (eg, Xyzal®), loratadine, mizolastine (Mizollen®).
A nasal sprays containing an antihistamine (azelastine [Rhinolast®]) is also available. Nasal sprays containing sodium cromoglicate (eg, Rynacrom®) or ipratropium (eg, Rinatec®) are also available for hay fever.
Decongestants may help to control the symptoms of a congested nose and are available in many over-the-counter preparations (eg, Sudafed® and Galpseud® [both containing [pseudoephedrine]). They should only be used on a short-term basis (up to five days at a time) or symptoms may become worse when the drug is stopped.
Combination preparations containing both an antihistamine and a decongestant are also available over the counter in pharmacies. These include Galpseud® Plus (chlorphenamine and pseudoephedrine) and Haymine® (chlorphenamine and ephedrine).
Nasal sprays containing corticosteroids may also be used to treat hay fever symptoms. Ingredients include beclometasone (eg, Beconase®, Nasobec®), budesonide (eg, Rhinocort® Aqua), fluticasone (Avamys®, Flixonase®, Nasofan Aqueous®), mometasone (Nasonex®) and triamcinolone (Nasacort®). Some of these are available to buy from pharmacies but some are only available on prescription.
A combination nasal spray containing a corticosteroid and an antihistamine (Dymista®) is also available on prescription.
A medication-free nasal powder spray (Care Allergy Defence®) can be used to form a protective barrier in the nose against airborne allergens, such as pollen, dust and pet allergens.
Eye drops containing sodium cromoglicate may be used to relieve the symptoms of redness, itching and watering and can also be bought in pharmacies. Eye drops containing antihistamines, corticosteroids or anti-inflammatory compounds are also available. These eye drops are available only on prescription.
Further information available from:
LEFA Business Park
Kent DA14 5BH
Helpline: 01322 619898
Fact sheet provided by MIMS
Date last reviewed: May 2014