This deep conditioner should be left on the hair for 3–5 minutes and rinsed thoroughly. Frizz Ease Miraculous Recovery Deep Conditioner was formulated to work quickly and effectively, therefore leaving it on the hair for an extended period is not necessary. Extending the length of time this product is on the hair will not cause any adverse effects, however it may make it harder to rinse out, especially if the product is allowed to dry on the hair.