Managing allergies

What is happening

An allergy is the immune system treating something harmless as a threat. Contact with the substance triggers the release of histamine and other compounds, and those produce the swelling, itching, streaming and wheezing that follow.

The tendency runs in families, but it is not simply inherited. Environment and exposure matter too, and the reasons allergy has become more common are still being worked out.

The common triggers are pollen, house dust mite, animal dander — cat more than dog — mould spores, certain foods, insect venom, latex, and substances that act on the skin by contact.

Reducing exposure, honestly

Avoiding the thing is the obvious first move, and it works to very different degrees depending on what it is.

For animal allergy, keeping the animal out of the bedroom makes a real difference, because that is where the most consecutive hours are spent. For pollen, keeping windows shut when counts are high, and showering and changing after being outdoors, does more than treating the pollen that is already indoors. For house dust mite, the useful measures are in the bedding and the humidity rather than in the air.

One avoidance measure is routinely oversold. Home air purifiers are often presented as straightforwardly effective, and the picture is more qualified than that: filtration gives modest benefit at best, does very little for house dust mite allergy, since that allergen sits in bedding and soft furnishings rather than hanging in the air, and some types of purifier — the ozone-producing ones in particular — are best avoided altogether.

Antihistamines

These are what most people reach for, and they help — particularly with itching, sneezing and a runny nose. They do less for a blocked nose.

The useful distinction is between the older sedating ones and the newer non-sedating ones. Chlorphenamine, promethazine, hydroxyzine and diphenhydramine make people drowsy. Cetirizine, loratadine, fexofenadine and acrivastine generally do not.

Non-sedating is the sensible default, and the sedating ones carry a real caution: they impair coordination, reaction time and judgement, so driving and operating machinery are out after taking one. They are occasionally useful where symptoms are preventing sleep.

There is not much evidence that any one antihistamine outperforms another, and people often try two or three before finding one that suits them. A pharmacist can advise without an appointment.

A note on names. Drug brands differ between countries, and the same brand name sometimes covers an entirely different active ingredient in another market, so the generic name in the small print is the thing to go by rather than the brand on the front of the box.

The treatment most people have never properly tried

For hay fever and other allergic rhinitis of any severity, the most effective treatment is not an antihistamine tablet. It is a steroid nasal spray.

UK guidance is direct about this: topical nasal corticosteroids are the treatment of choice for moderate to severe disease. Where symptoms remain poorly controlled, a spray combining a nasal steroid with a nasal antihistamine works better than either alone.

Two things stop people getting the benefit. The first is that these sprays take days to weeks of regular use to reach full effect, so anyone who tries one for two days and concludes it does nothing has not actually tested it. They are preventive rather than on-demand. The second is technique — aiming outwards, away from the central partition of the nose, rather than straight up.

Started a couple of weeks before the relevant season and used daily, a nasal steroid changes the experience of hay fever for a great many people who have spent years on tablets alone.

Steroids by mouth

Oral steroids are sometimes listed casually alongside antihistamines and hydrocortisone cream. They do not belong in that company.

A short course of oral corticosteroid can bring severe symptoms under control, and it is sometimes the right thing. But these are prescription medicines with substantial effects on the whole body, used briefly and under supervision, not an everyday option. Injected depot steroids for hay fever have fallen out of favour in the UK for the same reasons.

Immunotherapy

Everything above treats symptoms. Immunotherapy is the one treatment that changes the allergy itself, by giving gradually increasing doses of the allergen over about three years until the immune system stops reacting.

It is a specialist treatment reserved for a narrow set of situations — severe hay fever not controlled by medication, house dust mite allergy, and severe reactions to wasp and bee stings, where it is strikingly effective. It is reached by GP referral to an allergy clinic, and it is given both as injections and, increasingly, as a daily tablet under the tongue.

When it is not a nuisance

Allergy is often described as a nuisance, and for most people, most of the time, that is both accurate and reassuring. Two categories are different in kind rather than in degree, though, and each has its own article.

Food allergy and insect sting allergy can both produce anaphylaxis, which needs adrenaline within minutes and an ambulance. Asthma triggered by allergy is also a serious matter rather than an inconvenience.

Allergies are also not generally curable, whatever is implied by the way they are sometimes written about. They are managed, often very well, and some fade of their own accord. Immunotherapy comes closest to a cure and is available to relatively few. Treating allergy as a problem to be managed properly, rather than one to be solved or simply endured, is the realistic position.

Where to start

A pharmacist is the right first stop for ordinary symptoms, and can advise on sprays, tablets, eye drops and creams without an appointment.

A GP is worth seeing where symptoms are not controlled by over-the-counter treatment, where they are interfering with sleep, work or school, where asthma is involved, or where there has been any reaction affecting breathing or involving more than the site of contact. That last one is not a wait-and-see matter.