Is there something stronger to fight tree pollen allergy?

I'm sure you get asked this a lot, but which antihistamine is best? I'm allergic to tree pollen, and as usual at this time of year I'm constantly sneezing and blowing my nose. I've tried cetirizine and loratadine, and when I take one a day, as it says on the packet, neither really makes much difference. Would it help to double up the dose, or is there something stronger I could try?

- Dr Rosemary Leonard

Many people associate hay fever with allergy to grass pollen during the summer months, but allergy to tree pollens, which appear in the spring, are nearly as common, and can cause severe symptoms including watering itchy eyes, a streaming blocked nose and sometimes a tickly cough as well.

Those allergic to alder, hazel and yew tend to start getting symptoms in February, and in March it's birch pollen that causes problems for a lot of people, with symptoms lasting through till mid May.

There are several different types of antihistamine available, and the response to them and the side-effects they cause can vary a lot between individuals. The older types, such as chlorpheniramine, are no longer recommended as they are renowned for causing drowsiness (though this can be a benefit if symptoms are disrupting your sleep).

And though the more modern ones such as cetirizine, loratadine and fexofenadine are less likely to send you to sleep, if taken in large doses they can, along with giving you a very dry mouth. This is why you should stick to the recommended dose, particularly if you have to drive or operate machinery.

The key to managing hay fever effectively though is not to rely on tablets alone, but rather to use a nasal spray and eye drops as well.

Nasal sprays containing anti-histamines are available from chemists, but those containing steroids, particularly fluticasone, are often more effective.