why do bearded dragons open their mouth


While basking, a bearded dragon might hold its mouth open. In brief, this is normal behavior. In fact, this is how they regulate their body temperature. On a side note, this might be a sign to double check that the basking temperature is not too hot. Also, an open mouth should only be a concern if your reptile is showing signs of a respiratory infection.

Why do bearded dragons open their mouth? The reasons why bearded dragons open their mouth are mostly not alarming. Most of the time bearded dragons do that to regulate their body temperature. It can also be a sign of aggression or defensive behavior.

The following information will explain why bearded dragons open their mouth:

  • Gaping
  • Possibilities to consider when a chilly bearded dragon opens his mouth
  • Beard stretching and yawning
  • Aggression and defense
  • What to do in case the bearded dragon is opening its mouth to show a defensive behaviour
  • Mouth hanging open and recommendations
  • Bearded dragons respiratory infection
  • Causes of respiratory issues in a bearded dragon
  • How to treat a bearded dragon’s respiratory disease
  • Prevention of respiratory disease in bearded dragons
  • How to tell if your bearded dragon has respiratory infections


The first and most common reason for a bearded dragon’s open mouth is called “gaping.” Any dragon you keep at the right temperature will gape frequently while they bask.

Likewise, it is a form of thermoregulation in which they vent excess heat out of the mouth. The first defense against overheating. Where humans sweat, bearded dragons gape. However, the behavior isn’t a sign of discomfort.

In fact, they do this to prevent heat buildup once they achieve the perfect internal temperature. In addition, a gaping bearded dragon is a happy bearded dragon. Not too cold, and, not too hot due to their personal ventilation technique.

Possibilities to Consider when a Chilly Bearded Dragon Opens his Mouth

Beard Stretching and Yawning

  • Beard stretching
  • puffing, or
  • flaring is another normal behavior for bearded dragons. But, to the unprepared witness, it may appear that your bearded dragon is experiencing a demonic possession. While the realists out there may think it is choking.

Despite the

  • The freakish head movements
  • frog-like beard puffing, and
  • erratic opening and closing of the mouth, there’s no need to panic. This is simply how a bearded dragon stretches his or her beard.

Bearded dragons also yawn, which looks like… well, a yawn. It is sometimes accompanied by a small beard stretch.

Aggression and Defense

As most of us know, bearded dragons are

  • docile, and
  • friendly reptiles. As a result, aggressive behavior toward humans is rare. However, you may find that you’ve triggered defensive behavior in your pet.

Once, I startle my lizard by towering over him during a trip outside, which usually leaves him nervous. He quickly turns towards me, opens mouth, puffs out beard, displaying his best impression of a fearsome creature that is ready to pounce.

After a moment, he realizes I am the same human I have always been. Then it allows me to sit down. Aggressive bearded dragons are not unheard of, though. And after having my finger mistaken for a worm, I can attest to their jagged little teeth.

However, while a bearded dragon could never take your finger off, they are capable of inflicting a nasty cut.

Therefore, always respect the animal’s body language. Aggressive dragons might

  • puff
  • hiss
  • leap, and
  • gape. But most of us will never see this. In general, only dragons that have a bad history with humans will ever act this aggressively.

What to do In-case the Bearded Dragon is Opening its Mouth to Show a Defensive Behavior

If you think that your bearded dragon opens its mouth because it shows a defensive behavior towards you. Caging can help to create a safe place for your bearded dragon.

For example, get these plants and cover two or three sides of the bearded dragon enclosure with plants.

This way your bearded dragon can not see what is going on around its tank. And this helps to calm down an aggressive or scared bearded dragon. Also, you can get a background like this to cover a side of the bearded dragon’s tank.

Another great way to make the tank comfortable for your bearded dragon is to get a hide. So, I recommend that you get this hide. It is cheap, you can choose the size you need and it will do the job perfectly.

Mouth Hanging Open

A sign of Metabolic Bone Disease is a slack jaw. Hence, If the bearded dragon’s mouth is constantly open and has difficulty hanging onto food, it could be a sign of slack jaw.

This condition should be seen by a reptile veterinarian immediately to test for Metabolic Bone Disease. Likewise, the veterinarian can perform a blood test to evaluate calcium levels in the blood.

Also, It can be very common for the bearded dragon to open its mouth while on the basking perch for short periods of time. This is a way to cool off while directly under the basking bulb.

In general, this behavior is very similar to the way a dog pants to cool off and completely normal.


If you suspect slack jaw, seek a reptile veterinarian immediately. In the meantime, offer soft foods to the bearded dragon such as baby food or soft wax worms. Give him food that he will swallow with ease.

Meanwhile, to help prevent slack jaw, or Metabolic Bone Disease, make sure you are providing adequate UV radiation.

Importantly, use a mercury vapor bulb or fluorescent bulb specially designed for desert-dwelling reptiles. Supplement the diet by dusting food items with calcium powder.

Bearded Dragons Respiratory Infection

Another important reason for bearded dragons to open mouth is the only reason for concern.

Respiratory infections are as a result of the case where humidity exceeds 40% for a prolonged period.

In particular, bearded dragons are animals of the dry woodlands of Australia, not adapted to breathe moist air. Thus, making respiratory infections common in humid regions.

Keepers should own a hygrometer and use these methods to maintain low humidity in enclosures. Also, if you use a water bowl, keep it small and away from heat sources.

Likewise, do not use barks or mosses in terrariums, as they retain moisture. However, if the humidity is high in the enclosure, add more ventilation.

If the humidity in your house is too high, and no other methods work, buy a dehumidifier to place in the room with your bearded dragon.

Causes of Respiratory Issues in a Bearded Dragon

  • Low temperature
  • Bad ventilation
  • Excess humidity
  • Bad diet

How to Treat a Bearded Dragon’s Respiratory Disease

If you suspect that your bearded dragon is suffering from respiratory disease, you should take them to a reptile vet immediately. A reptile vet can provide accurate diagnosis and correct treatment, probably requiring medication.

Your dragon may be given medication to administer daily, orally, using a syringe. The dosage depends on the size of your dragon.

You should also find the cause of the disease and correct it for the future health of your dragons.


  • Ensure that the dragon’s vivarium is at the correct temperature and humidity.
  • Ensure they have adequate ventilation.
  • Provide them with a good balanced diet and supplements such as calcium.
  • If any dragon has the disease, keep them away from any other dragons to avoid affecting the others

How to Tell if your Bearded Dragons have a Respiratory Infection

A bearded dragon with a respiratory infection might look like it is gaping all day. However, this won’t be in response to basking temperatures. Instead, the dragon is attempting to breathe through its mouth.

Watch for

  • mucus in or around the mouth and nose
  • labored breathing
  • wheezing, or
  • crackling with each breath.

Sick dragons may become lethargic and lose appetite. Hence, contact a vet immediately if you suspect your dragon has a respiratory infection. As there is no effective way to treat it at home.

Meanwhile, for bearded dragons you do not give treatment, fluid will build up in their lungs, eventually suffocating the lizard.

Signs and Symptoms That Your Bearded Dragon Is Sick

  • Raspy breathing
  • Forced exhalation causing a coughing noise
  • Gaping as they have difficulty breathing
  • Puffing up around the throat
  • Mucus around the nose and mouth
  • Loss of appetite


So, why do bearded dragons open their mouths? Bearded dragons open their mouths as a response to many different things, and most of the time, there’s no reason to worry.

Gaping is a good sign when it comes to basking, and they stretch their beards just to, uh, creep you out?

But sometimes it can be a sign of stress, defensiveness, or worse yet severe illness. When you pay attention to the dragon’s normal behavior, it will be easy to distinguish one of these things from another.

For those who care for their bearded dragons, and act on their best judgment. I’m sure everything will turn out fine.