My 2 year old male Westie (Angus) has just started to bite and lick his paws (front and back) and seems to do this for ages. If you try to stop him he growls (which is unlike him). A friend of my partner suggests washing his paws in Nizoral anti-fungal shampoo. This is a human shampoo and I'm concerned that it may have side-effects on him.

Any ideas what is causing his itchy paws?

There could be various reasons for this however I would recommend keeping his feet as dry as possible, make sure the hair between the pads is cut short and always cleared.   Hibiscrub is very good for given the feet a scrub.  a small amount of athletes foot powder or thornit powder could also be used to releive the itching. It can become a habit in general, it is really trying th break it.
Nizoral
I have not personally used Nizoral so can't comment but others have with success as a wash.

Keep him off the grass for a bit also.

Pam

Tis may or may not be diet related; read my reply to red toes :D

Nizoral is often prescribed for dogs and should be perfectly safe for use on his paws.  However, bear in mind you are treating symptoms not the cause! 

Other things to think about are salted roads, fertilisers etc etc

HTH

Gus also has a problem with his paws although it seems to be confined to the two front ones only . We have tried the usual - steroid creams , antibiotics, antihistamines, thornit and now it looks likely he will need a skin sample sent to the labs to try and diagnose why he is doing it.
Vet did say to try Malaseb (sp?) Shampoo which is antifungal and can only be prescribed by vet . It needs to be used for 6 weeks which isnt up yet . So we will see how that goes although he is already starting to lick them again after the antibiotics have finished :(
Some say it can be due to boredom, but I feel that for Gus this isnt the reason as he will stop to lick his paws in the middle of a good game :(
It seemed to occur with the onset of Autumn and all the wet muddy weather - although we always dry his feet off after being out . He seemed fine in the dry warm weather - so whether there is a connection or not I dont know .
He is mainly walked in the woods too
Can you keep in touch and let me know how he gets on
Lel