Yes, it is safe to use a clarifying shampoo on curly hair. However, it would be best not to overdo it, as this can lead to dry and brittle curls. If you're following the Curly Girl Method, you should be clarifying your hair once a week. However, if you feel like your hair needs it more often, then go ahead and clarify as often as necessary. Just be sure to follow up with a good conditioner to avoid drying out your hair.