My cat has a bald patch where I treated her with a flea and tick treatment.

[MehgaLegs]

It's the second dose, three months after the first, she didn't react to the first dose at all. She has a bald patch on the back of her neck where I put the spot on stuff two nights ago. Skin looks ok, no rash or reaction and she is her normal rabbit catching, sunbathing self.

Anyone else ever seen this problem?

Which one did you use? I have seen it most often with supermarket/pet shop brands. Sometimes they get soreness develop. You should wash the area well with mild soap and water then rinse, just to be on the safe side. Avoid that brand again.

Yes, I did use a cheapy - the Bob Martin one but I can't afford Frontline.

I did give the area a bit of a wipe with warm water yesterday when I saw the bald bit. The fur around it looked greasy and I cleaned it off.

Will her fur grow back do you think?

Some will, but some don't. Time will tell on that one.