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.
Hair removal methods may cause razor bumps by either creating a sharp hair tip that re-enters the skin away from the hair pore (extrafollicular penetration) or by the hair shaft breaking off at different lengths and piercing the follicle from within the skin (transfollicular penetration).