There are lots of different causes of bad breath, and that can impact what your breath actually smells like. In addition to obvious culprits like garlic and onions, alcohol breath, and bad breath caused by poor oral hygiene, there are other types that might indicate an oral or general health problem. Here are some examples of types of bad breath smell and what they might mean:

• Sweet, fruity or like nail polish – a potential sign of diabetes or a side effect of a low-carb diet like keto.
• Rotten – gum disease, tooth decay, or an infection in the mouth, throat or lungs.
• Sour – a possible symptom of acid reflux, when stomach acid travels up into the esophagus (food pipe).
• Fecal – potentially a sign of a chronic gastrointestinal disorder or a bowel obstruction (a medical emergency).
• Ammonia – a sign of kidney disease.
• Musty – a sign of liver disease.
• Fishy – a sign of a disorder called trimethylaminuria, in which your body cannot break down a certain enzyme. Sweat and urine will usually have the same fishy odor.

It may feel awkward to ask someone to smell your breath and give you feedback, but this can be really helpful. You can try asking someone you’re close with, and ask them if they notice a white coating on the back of your tongue, too; this is a common sign of bacteria that causes bad breath.

If you’re too embarrassed to ask a friend, you can always ask your dentist. A dentist can assess the air from your mouth and nose to find the source of any odor. Whatever the outcome, a dentist will be able to help you treat or prevent bad breath from happening in the future.

Need to check how your breath smells quickly? Try the sniff test. There are a couple of ways to do it. You can start by cupping your hands over your mouth and nose, breathing into your hands, and then seeing if you notice a smell. Or if you lick your wrist, let it dry for a moment, then take a whiff, you should be able to get an idea if your breath has an odor. Another method is to floss toward the back of your mouth, then smell the floss. Or gently scrape your tongue using a tongue scraper or soft bristle toothbrush, then smell the scraper.

There is a way you can taste your breath, which will give you the same information as smelling it. For example if you have a condition such as dry mouth, or if you’re dehydrated, you may be able to taste your breath. Signs of dry mouth include thick, foamy saliva and a change in taste. Just rinse your mouth out with water, which washes away any food debris and stimulates the cleansing flow of saliva, and follow your usual dental hygiene routine.

If you’re still worried about your breath, the best thing to do is what you should be doing anyway! Brush twice a day and floss or clean between your teeth at least once per day. Sometimes your toothpaste doesn’t do enough to remove the bacteria affecting your breath, so rinse with mouthwash or use a water flosser to get rid of any lingering, odorous bacteria.

If you think your breath smells bad because of your diet, it can help keep a food journal. Another option is to temporarily cut out certain foods from your diet to see if your breath improves.

It can be tricky to figure out how to tell if your breath smells, but luckily, it’s not impossible. If you think you might have bad breath, don’t worry—there are plenty of ways to help prevent and treat it. Of course, the best way to avoid bad breath in the first place is to keep up a good dental hygiene routine, but sometimes bad breath has mysterious causes, like diet or health conditions, so don’t be too hard on yourself.

If you have persistent bad breath no matter what you do, it’s essential to talk to your doctor or dentist. A medical condition, such as a digestive problem, can cause bad breath, so bring it up with a medical professional as soon as possible.