Yes, it is perfectly safe to eat stinging nettles once they’ve been blanched. In fact, they’re extremely healthy as they are packed with vitamins A, B & C as well as a wide variety of minerals. They possess a fresh, green, spinach/mint flavor and can be prepared similarly to other cooked greens or used to make nettle tea.
Warning: Do not handle raw stinging nettles with your bare hands. Use gloves. After nettles are cooked, the stinging agent is dissolved and they are safe to handle and eat.