Get morning breath? Here's why it smells like a dead animal crawled into your mouth.

Image: iStock.

We all know the feeling. You go to bed with minty-fresh breath only to wake up in the morning smelling like a sewer rat made a home in your mouth.

As with pretty much everything else, science has figured out exactly why  you wake up with morning stink mouth.

Related: The nine easiest (and surprising) ways to get bright, clean teeth. 

During the day, our saliva helps to keep the bacteria in our mouth at bay. At night, however, we don’t produce as much saliva, which means the colonies of bacteria in our gobs have a massive party and eat all of the small food particles and dead cells available.

Your rancid morning breath occurs because the bacteria produce a bunch of different stinky compounds as waste products.

Four of which are…

1. Methanethiol: this compound has the smell of rotting cabbage (AKA fart smell).

2. Isovaleric acid: this guy is responsible for that cheesy, stinky foot smell after a long day of wearing your shoes. (Post continues after gallery.)

3. Cadaverine: This has been said to cause a smell of rotting fish or rotting flesh. *Vom*

4. Hydrogen Sulfide: This compound smells of rotting egg.

So if you wake up to someone telling you your breath smells like poo in the morning – they’re probably not far off.

So what can you do to prevent bad breath? Well, unless you're willing to get up during the night to brush your teeth at regular intervals, it's just one of those delightful things we all need to deal with.


Certain foods however can make the morning situation worse, with things like garlic, onion, cheese, wine and coffee often cited as being contributors to smelly breath.

One of our favourite ways to wake up in the morning is with this breakfast...(post continues after video)

It's also important if you're a regular sufferer of bad breath to make an appointment with a dentist to determine whether there is a more sinister underlying cause for the odour, like tooth decay or gum disease.

If you're given the all clear, the best plan of action is to ensure you have good dental hygiene which means brushing two to three times per day and flossing between your teeth. Dentists also recommend brushing your tongue to eliminate any bacteria that may be hanging out there.

Related: "I made my husband vagina art and ended up in hospital."

Sipping water regularly can also assist in keeping bacteria at bay by washing it away before it has a chance to build up and cause offence.