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Home > Bearded dragons > Why Does My Bearded Dragon Have Their Mouth Open? 5 Vet-Reviewed Reasons

Why Does My Bearded Dragon Have Their Mouth Open? 5 Vet-Reviewed Reasons

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Bearded dragons have a lot of unique characteristics and traits, not least of which is their head bobbing and arm waving habits. A lot of their actions are a result of evolution and a throwback to the habits of their wild ancestors. One thing you may have seen your beardie doing and that has left you scratching your head is the opening of their mouth.

You may have seen your beardie basking on a rock with their mouth open, or hiding in cover and opening and closing their mouth. While it isn’t necessarily a negative sign, you should determine why they are doing it to find out whether they’re in pain, suffering from anxiety, or simply self-regulating temperature.

Read on for the reasons your beardie might have their mouth open.

divider-bearded dragon

The 5 Reasons Your Beardie Has Their Mouth Open

It is most likely that your beardie is regulating their temperature through an action known as gaping, but there are other causes why your pet reptile could be partaking in this odd-looking activity.

1. Gaping for Temperature Regulation

Lizards like bearded dragons are unable to sweat, which is the main method of regulating body temperature for humans. We sweat to cool the body down. A lizard must find other ways to regulate its body temperature, and opening their mouth is one such technique. In this instance, the action is called gaping and it vents excess heat from the body, therefore reducing the body temperature.

It is most common for a beardie to gape while they are basking, which usually means that they will do this while sitting on a rock under a heat lamp. If they are gaping in other areas of the tank, you may want to investigate to ensure that there are some cool spots where your dragon can go to cool down.

NOTE: A bearded dragon’s terrarium should have cool and hot spots to allow them to heat up and cool down as required.

Do Bearded Dragons Sleep With Their Mouth Open?

It is not common for beardies to sleep with their mouth open. It could just be an unusual quirk of an individual beardie, but it may also be a sign that your dragon is too hot during the night. The nighttime temperature of the cage should be cooler than the daytime, and especially around the area where your bearded dragon sleeps.

Why Is My Bearded Dragon Sticking Their Tongue Out?

As well as opening their mouth, your bearded dragon may stick their tongue out. This enables your dragon to further reduce their body temperature to a reasonable level and is common during gaping.

Bearded dragon opens its mouth showing its teeth
Image By: Opayaza12, Shutterstock

2. Beard Stretching

A bearded dragon is so-called because of the beard around its neck. They can puff their beards out, and some can change the color or the intensity of the color in their beard. It is common for a male beardie to stretch his beard, as it is known, when he feels threatened or when being aggressive. At this time, this beard will often turn black too. Although this is an instinctive reaction when being aggressive, the beardie may also perform the action at any time. They also stretch their beard as a means of exercising it and practicing the action. Your bearded dragon may also stretch their beard more often just prior to shedding.

Do Beardies Yawn?

Beard stretching can take many forms. Your beardie might stretch their neck, raise his head, open their mouth, and change the color of their beard. This can look like they are yawning. What’s more, bearded dragons, like most animals, do also yawn, and this is not a cause for concern.

Why Is My Bearded Dragon Opening and Closing Their Mouth?

The continuous opening and closing of his mouth could be your male bearded dragon stretching his beard and practicing.

3. Aggressive and Defensive Behavior

Most of us know the bearded dragon to be a calm, placid, and friendly little lizard. They usually get along very well with their human owner, and can even take well to strangers. However, they can still feel threatened and appear aggressive in nature if this happens.

Bearded dragons have a good understanding that humans are much bigger than they are, so rarely act aggressively towards us. But if you startle your beardie, they will act accordingly. Their aggressive response might include opening their mouth and stretching their beard to try and intimidate and frighten you. Although an aggressive beardie is rare, the open mouth might be accompanied by hissing, charging, and even some biting.

bearded dragon close up
Image By: paintings, Shutterstock

4. Feeling Threatened

It isn’t just humans that can startle bearded dragons, of course. If you keep more than one in the same cage, which is not usually recommended, it could be that one beardie, usually the male, is being aggressive towards the other. This can startle the female, who may react by opening her mouth and hissing.

If you have other pets, they may be causing a startled reaction by approaching the cage, attempting to bat at the beardie, or by making loud noises and scaring the dragon. If your beardie’s cage is close to the window, it could even be the noise of passing cars or neighbor dogs that is causing an aggressive reaction.

Try to determine any noise or other activity that might be causing the reaction and look for ways to mitigate it. Move the cage to a quieter area, or away from the window, if this will help.

5. Respiratory Infection

The major cause for concern if your beardie has their mouth open all the time is a respiratory infection. These can occur when humidity levels are too high for too long. Bearded dragons are not adapted to breathe humid air, so you need to keep the humidity level at an appropriate level in their tank (35 to 40 percent is ideal).

Keep any water bowl away from heaters, don’t use bark or other moisture-retaining items, and add more ventilation. Ensure that the moisture level does not rise above 40% for long. Signs of respiratory infection include gaping all day, even when not basking, along with mucus in and around the mouth.

Other signs of a respiratory infection in your bearded dragon include the following:
  • Sneezing
  • Discharges from one or both eyes
  • Discharges from one or both nostrils
  • Bubbles from either the mouth or nose
  • Very rapid, shallow, and forceful breathing (abdomen may be involved)
  • Lethargy
  • Decreased or no appetite

If you see these signs in your bearded dragon, you will need to seek veterinary assistance immediately because such infections cannot be treated successfully at home.

bearded dragon on a rock
Image By: T Ince, Pixabay



In most instances, it is quite natural for your bearded dragon to have their mouth open, but there are some cases where it can be cause for concern. It might be a sign that your beardie is startled or scared, that they are aggressive, or, worse still, that your beardie has a respiratory infection that is affecting their breathing and needs immediate attention. It is more likely, however, that your beardie is gaping or regulating their body temperature and using their open mouth to vent hot air from their body. If you’re in doubt about your bearded dragon’s welfare and aren’t sure why they’re opening their mouth, you should consult with an exotic veterinarian to ensure that your pet is healthy and their enclosure is set up properly.

Featured Image Credit: Milchdrink, Pixabay

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