Hi in the past I have bought a generic one from Home Bargains (virasorb) it appears to have the same amount of active ingredient, Acicovir 5% and costs around 99p for a 2g tube. I honestly couldn't tell you if it's any good as I have never remembered to apply it. It has to be applied at the tingly time, instead I apply neat lavender oil which I swear by, it always nips it in the bud and prevents it developing into a mouthful of blisters.