Are there any natural anti-lice for cats?

I use Advantage drops from BAYER on my outdoor cat and it is effective for about a month.

However I feel bad each time that I apply it, because the cat becomes drowsy for a day or two and I fear that we also get contaminated by some nasty chemicals when we caress the cat.

On the other hand, if I don’t use the drop, the cat get infested regularly by lice in summer time.

So I’m wondering if there are some effective but natural alternatives available, which are harmless for cats and humans?