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Why Does My Bearded Dragon Keep His Mouth Open

Is your bearded dragon not moving with his mouth open?

Are you worried this could be a sign of something more serious?

It’s essential to know about the different body postures your reptile may show and what they could mean.

Knowing this is a vital part of being a responsible bearded dragon owner.

So, why does my bearded dragon keep his mouth open?

A bearded dragon will keep its mouth open for the following reasons:

  • To regulate heat and body temperature
  • As a form of stretching its mouth muscles
  • As a sign of aggression and dominance
  • Due to a respiratory infection
  • To display alpha traits to another bearded dragon

Read on for more details and how to tell the difference between the possibilities.

why does my bearded dragon keep his mouth open

5 Reasons Bearded Dragons Keep Their Mouth Open

In this section, we detail the reason for an open mouth and what to do to help (if you need to).

#1 Heat Regulation

Heat regulation is the most common reason for an open mouth.

When the bearded dragon is a little too hot while resting under the heat lamp, it opens its mouth to cool the rest of its body down.

You know this is why your beardy’s mouth is open when it does this for a long time while basking.

How Heat Regulation Works

All animals have a body temperature regulation process.

On humans, we sweat, which cools our bodies down.

Bearded dragons don’t have sweat glands, but opening their mouths is their version of sweating.

Keeping the mouth open lets an easier transfer of air temperature occur inside and outside their bodies.

What You Should Do About Heat Regulation


This behavior is called gaping, and it’s a sign the dragon has achieved the perfect balance of inner temp.

They want to be hot when basking.

The heat from the lamp (or sun in the wild) gets the body temp up while the open mouth lowers it to the exact right temperature.

If your dragon ends up hiding instead of basking, this is a sign the temperature in the enclosure and under the basking lamp may be too high.

#2 Stretching

Just like other animals, bearded dragons need to stretch and move all of the parts of their bodies.

They also yawn just like other animals as well.

Stretching may be the cause of your bearded dragon’s open mouth.

You’ll know if this is the cause when your dragon does this for a short period.

How It Works

Bearded dragons, like other creatures, have a built-in sense when a muscle hasn’t been in use for a while and needs to stretch for safety.

In humans, this happens after not using your muscles for an extended period, such as after sleeping , sitting in a meeting, or riding in a car.

It’s the same for bearded dragons.

They have a lot of muscles in their head and face, including their beards.

When they move these for stretching or yawning, the mouth needs to be open because all of these parts work together.

What You Should Do

Enjoy the show!

It may look alarming and trick you into thinking your bearded dragon is crazy.

Their stretching looks a little twitchy at times, but it’s normal.

When their beard is up, it also seems aggressive, but it’s just simple stretching.

#3 Aggression

On the other hand, if the beardy feels threatened or panicked, it opens its mouth as part of an aggressive posture.

Long-term stress on your pet can result in poor health and disease, so it’s essential to address this.

You know this is the reason your beardy’s mouth is open when the mouth is open, the beard is up, the dragon hisses, and the reptile attacks anything moving in the tank.

When an animal feels threatened, its “fight or flight response” is activated.

In the case of the bearded dragon, this means it’s raising its beard and puffing out its chest to appear larger and more threatening to the other animal.

They also open their mouth wide and hold it there.

This adds to the size illusion of the beard and body and shows it’s ready to bite.

A bearded dragon bite isn’t venomous (although they do produce harmless venom), and it won’t seriously injure you. But it does hurt.

Your bearded dragon is stressed out! It would be best if you calmed it down.

Check out our 7 tactics on how to calm down a bearded dragon for detailed information.

In general, to calm your beardy, you need to do these three things:

  1. Remove the threat/overstimulation.
  2. Put your bearded dragon where it feels safe.
  3. Give it time to get used to your presence again.

If you don’t, your bearded dragon may not calm down quickly and remain stressed.

They’re also smart creatures and will begin to associate you with threatening situations if you don’t take steps to calm them.

#4 Respiratory Infection

Respiratory infection is the big one to watch out for.

A bearded dragon may be keeping its mouth open if it has a respiratory infection.

Respiratory infections present much like gaping for heat regulation, but look for these other signs:

  • Mucus around the eyes or nose
  • Wheezing, coughing, or crackling when breathing
  • Extreme lack of energy and appetite

“Respiratory” refers to the breathing and oxygenation process.

When your beardie is sick, its breathing capacity may be compromised .

To get more air, it opens its mouth to access as much oxygen as possible.

When you see the signs above and suspect a respiratory infection, get your bearded dragon to the vet.

Unfortunately, it’s not something you will be able to fix on your own.

This happens even with the best care.

Just get your pet to the vet, and it’ll all be just fine.

#5 Alpha Traits

If you own multiple bearded dragons that can see each other, one of them is likely displaying that they’re the alpha.

In nature, these lizards are solitary creatures, choosing to live alone.

If you’re housing bearded dragons where they can see one another, it’s bound to cause problems.

This is where the more dominant one will leave their mouth open to show the other one who’s alpha similar to head bobbing and a black beard.

This can cause the less dominant or submissive bearded dragon health issues such as metabolic bone disease since they’ll become stressed and often stop basking.

You will see them begin glass surfing, avoiding their basking spot, not eating the juicy wax worm, and you’ll see this beautiful exotic pet go through pain.

To prevent this, always keep your inland bearded dragon in separate tanks and where they cannot see each other and you should see the aggressive behavior go away.

Keeping them in the same room is fine as long as there is a visual divide between them and they can’t physically see each other.

Some people also feed their pets in separate tanks for various reasons and if you’re interested in learning about this we have a post covering feeding bearded dragons in separate tanks you’ll like.


Now you know why your bearded dragon keeps his mouth open.

This bearded dragon behavior is seen in all stages of their life so even your baby bearded dragon lizard may do this.

In most cases, this is perfectly normal behavior as a result of stretching or heat regulation.

But it might be a sign of stress or respiratory infection.

Use the guide above to help you decide what you need to do, and when in doubt, go to a reptile vet.

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