The Good: Pyrethrins, for the most part, do seem to be relatively safe for most pets, though dosage is still the key. Many on-line sites list pyrethrins as being safe for cats, and as far as we can tell, used judiciously, they are not too much more toxic for cats than they are for dogs.
Yes: Razor bumps will usually go away when you stop shaving. There are a few things you can do to prevent them in the future. Shave in the shower so the heat can soften the hair, and use a shaving gel. Always use a brand new razor, and shave in the direction that your hair grows. Moisturize after shaving.
Check all around your body for bumps. If they're near stubble on your legs or face, change your razor blade and use a more skin-sensitive shaving cream. Wash the bumpy area regularly with a mild cleanser for two or three days. If the bumps go away quickly, they could have been bug bites.