If you think storing your toothbrush in a cover will protect it from the germs spewing out of a flushed toilet, you’re right. But you’re setting yourself up for other problems. Because a toothbrush inside a cover will have a hard time drying out completely. And a damp environment means one thing: Germs! So leave your toothbrush out in the open to dry out every day. Microorganisms can grow on it still, but they’re unlikely to make you sick. And replace it every 3 months. By then, the bristles won’t be cleaning your teeth as thoroughly.