The incidences of all allergies have been rising. With hay fever, factors implicated may include warmer summers through global warming; increasing use of diesel fuel-diesel exhaust particulate binds to pollen grains and seems to enhance penetration into the respiratory mucosa; and planting of more silver birch trees, which are prohfic pollinators. Many factors seem to be involved, not least the individual's family history or genetic predisposition to develop hay fever.

What are the signs of Hay fever

Hay fever signs are usually restricted to the conjunctiva and upper respiratory tract and are occasionally accompanied by wheezing or 'hay' asthma. Theoretically, as with any allergy, generalised anaphylaxis can be developed with very high pollen exposure. Pollen may penetrate the larynx and be swallowed with nasal mucus. If it can get deep into the airways, skin and gastrointestinal tract, a systemic reaction is possible. Hay fever in those ailergic to silver birch pollen is often associated with localised oral itching from fruits. Oral allergy syndrome (OAS) occurs if certain stone fruits such as apple, cherry and peaches, as well as raw vegetables and hazelnuts, which contain a crossreactive protein, are eaten by birch pollen allergy sufferers. OAS, while unpleasant with mouth and tongue itching plus laryngeal irritation, doesn't usually lead to more severe food reactions or anaphylaxis. Raw, not cooked or canned food, causes the reactions.

What causes Hay fever

Hay fever is triggered by grass and tree pollens which are small and easily windborne and can penetrate deep into the airways. Brightly coloured flower pollens such as rape are much stickier and heavier, and tend not to penetrate deeply into the respiratory tract. Flower pollens are generally not windborne, but designed to stick to insects. When people develop hay fever they are aware of bright fields of rape but may not notice less colourful grasses nearby. Flower pollens are not a common cause of hay fever and when implicated it is the compositae (daisy and dandelion) family or weed pollens (mugwort, dock and nettle) that are culprits.

What are the treatments for Hay fever 

Whatever suits the persons symptoms and lifestyle is the best medicine, as compliance is pivotal. If patients don't use the treatment properly as prescribed, the symptoms will persist. Antihistamine eye and nose drops must be applied regularly, but the profuse coryza associated with hay fever often washes topical agents away. Oral antihistamines are ' most effective and may be used in combination with topical preparations such as cromoglycate and antihistamine nose or eye drops. The WHO ARIA guidelines for intermittent and persistent allergic rhinitis advocate a graded approach, starting with topical, then oral, antihistamines. If symptoms persist for more than four days a week and/or for four weeks or more, a steroid nose spray should be added for better symptom control.

The second generation non-sedating antihistamines such as levocetirizine, fexofenadine and desloratidine are most effective and have fewest side-effects, but come at a cost. Other preparations such as loratadine and cetirizine are cheaper, but some may find them to be modestly sedating. Desloratidine is a metabolite of loratadine, non-sedating and supposedly binds to the histamine receptor more than ioratadine. But levocetirizine, fexofenadine and desloratidine are all on a par, with little difference between them. If they are to be used continuously I like to swap between them every six months to prevent tolerance or tachyphylaxis, which seems to occur with antihistamines. Older preparations such as chlorphenamine (chlorpheniramine) and hydroxyzine should be avoided as they can cause considerable sedation and psychomotor retardation, which significantly impair quality of life. The old schools of thought recommend mixing antihistamines using non-sedating preparations during the day and adding a sedating preparation at night. However, these can result in some hangover effect the next day. Most leading experts now opt for using a second-generation antihistamine and increasing the dose until symptom control is reached - even if this means temporarily going above the recommended dose and using it off-label.

Injectable steroids for Hay fever

Injectable steroids are normally avoided for fear of unwanted side-effects such as muscle atrophy, unreliable absorption and pro longed side-effects. However, there is no evidence base to substantiate this, and many doctors feel that using a single injection of depot steroid at the height of the pollen season is a safe and effective option. Perhaps the treatment of choice for recalcitrant symptoms - and for special occasions when we need instant relief such as exams, weddings and maiden speeches - is a short course of oral steroids. This treatment (prednisolone 20mg daily for five to seven days) will more quickly clear obstructed nasal passages and allow deeper nasal penetration of topical steroid sprays.

Hay fever Home Remedy Treatments

Wraparound sunglasses and nasal douching with saline - commercially available as Sterimar - seem to help. A little Vaseline applied to lower nasal passages will afford some protection from pollen exposure. Other advice for patients includes: close car windows when travelling and use the air conditioner; keep bedroom windows closed during the day and don't hang out washing during midmorning and early evening; remove outdoor clothing when going indoors; wash hair in the evening, and take a shower when returning home from school or work; don't sit out of doors in the late morning or early evening when pollen counts peak; and plan the day and be aware of daily pollen counts in the media and on television. Alternative or complementary treatments remain popular with the public, who experiment with remedies including dilute homoeopathic extracts of red onion (allium), eyebright (euphrasia), sabadilla and herbal treatments such as butterbur and sambucos. The most investigated of these is butterbur (Petadolex) which has been shown to be as effective as some antihistamines, but the other remedies offer minimal benefit.

Last updated Jan 4/07