This issue of Mothball Breath usually is not a health issue. While it is true, kidney disease and diabetes and even anorexia can cause wierd breath, the major cause is not flossing properly. If you are looking here for answers, you should have already tried the following: Ask your friend to smell your breath. Then try different things and see what makes it better. Here are some suggestions that actually work: 1. Gargle with dilute Hydrogen Peroxide. Smell Test? Gargling will take out anything in the back of the throat if done properly. 2. Scrape the tongue. You can get a scraper or make one from a spoon. Smell test? That eliminates the tongue! 3. Floss your teeth - I mean really really well. If you are a person who has tightly packed teeth, I bet that's it. People who have had teeth pulled to make room for growth generally can remove food in the teeth easily. Count your teeth and see if your friends have the same number as you. The more you have, the more likely you need to floss often. Smell Test? Well if that did not do it, are you Skinny? If you are, your body may be breaking down muscle and the smell is a sign of poor diet. Eat more protein. Not Skinny? Do you drink milk, eat cheese, smear butter on your toast? You could be lactose intolerant. That is not a mothball smell but it is close. If none of these tips work, have a urinalysis done. You can do that yourself via online lab services. Look them up. If your test is alarming, see a doctor. If not, see a dentist. But my guess is you solved it when you flossed.