Anonymon,
Just to add that if you do start suffering with the head rushes from the Nitro and really can't handle them, the other alternative is Diltiazem cream, which I actually used after being unable to cope with the Nitro side effects. It works in the same way and I spent 7 weeks using it. It had a MAJOR effect in assisting the healing of my fissure and like Crackin Up, could not have reached where I am today without it. I'm also in the UK but 100% certain it's available in the US too....Just a thought! x