I am currently taking 10mg of clarytin once a day for hayfever, but it does appear to be working. It has in previously, what can I try instead. Andy?

Allegra (fexofenadine) or Zyrtec. You may want to try a different anti-histamine like Allegra (fexofenadine) or zyrtec. Sometimes switching to a different medication can make the difference. However, if those aren't helping with your symptoms either, it may not be allergies and you should see your doctor for an examination to determine the best treatment.
Other meds. You might try otc zyrtec, also an antihistamine/allergy med (that works on a different receptor). Drowsiness is its most common side effect. Or your fp could prescribe a nasal steroid spray like Nasonex (mometasone) (& others) which can be used in combination with the Claritin or zyrtec.