If your morning breath wilts flowers and triggers gagging sounds from your bedmate, don’t sweat it. Fetid morning breath is normal, according to a BMJ study.

Blame a dry mouth. Your saliva kills bacteria, including the types that cause an unpleasant odor to bloom in your maw, says Dr. Jeff Burgess, DDS, a retired professor of dental health at the University of Washington School of Medicine. But when you sleep, your saliva production and secretion plummet. Especially if you tend to sleep with your mouth open—snorers, pay attention—your mouth is going to get really dried out.

Unfortunately, there’s no reliable way to judge if your own breath stinks, finds a study in the Journal of the American Dental Association. Your nose quickly loses a bead on scents after a few seconds of smelling them. So the old palm-to-mouth trick doesn’t work, the study authors say.

Apart from trusting friends and coworkers to tell you if your breath blows, there are a few times when you can assume the odor wafting out of your mouth is going to be rank.

Both of these foods contain high concentrations of sulfur, a foul-smelling chemical that can pass through the lining of your intestines and get into your bloodstream and lungs, where it can putrefy your breath, finds a study from a Hong Kong-based research team. Since the smell is coming from your blood and lungs, there not much you can do apart from masking it with mints or gum.

Some of the amino acids found in dairy also contain sulfur. These dairy amino acids tend to break down in your mouth, and so can make your breath horrid in a hurry, the Hong Kong researchers say.

When your stomach and liver metabolize booze, the process yields a stinky byproduct called acetaldehyde, finds a study from Israel. Alcohol—especially red wine—can also dry out your mouth, making bad breath worse. Swishing water between drinks can help keep your mouth moist, and so knock down your bad breath. Gum or mints are also good for masking the acetaldehyde. Just skip astringent mouthwashes that contain alcohol, which can make your breath even worse.

First of all, the caffeine in coffee can slow saliva production and dry you out. Your favorite morning beverage also contains a molecule that, when digested, can produce a scent reminiscent of dead fish or sour milk, finds a study in (seriously) the Journal of Breath Research. Again, swishing water in your mouth during and after coffee can help.

Reflux and indigestion can force stomach acids and gasses up into your throat, where they can mess with your breath. Spicy food often contains high amounts of acid, which contributes to these digestion issues. Many spicy foods also contain those breath-ruining sulfur compounds.

Apart from coating your mouth with the scent of tobacco smoke, cigarettes and cigars also dry out your mouth, according to research from the Centers for Disease Control and Prevention. Marijuana likely has similar drying-out effects. Drink plenty of water, and keep mints handy.

Dry mouth is a common side effect of hundreds of prescription drugs, Burgess says. That includes antidepressants, allergy meds, and many other popular ’scrips. If the drug you’re taking is drying you out—and so promoting bad breath—dry mouth rinses and toothpastes are often effective, he says. You can buy these without a prescription at any drug store.

If you’re sick or have allergies, a clogged schnoz will force you to breathe through your mouth, which can dry you out and mess with your breath, Burgess says. Drinking lots of water and brushing your teeth and tongue more often than usual can help you clear away the smelly bacteria that may accumulate, he says.

If your pals and family have made you aware that you’re breath reeks pretty much all the time, talk to your doctor or see your dentist. Burgess says gum disease, gastrointestinal diseases, and some other underlying health conditions can make your breath bad regardless of what you eat. You need a docs help to get to the bottom of things.