Why is My Leopard Gecko Mouth Open? An Informative Guide

By Frank Miller •  Updated: 09/17/23 • 

Leopard geckos are interesting creatures that make excellent pets for reptile enthusiasts. Unfortunately, their solitary nature makes some of their body language expressions hard to understand, even for advanced keepers. If your scaly friend seems like he’s gasping for air, you’ve probably wondered: Why is my leopard gecko’s mouth open?

Your leopard gecko’s mouth is likely open because your pet is trying to regulate body temperature. This is a common behavior typically referred to as mouth gaping. Gaping in Leos can also occur because of severe health concerns like respiratory tract infection or metabolic bone disease.

Read on as we analyze 7 possible reasons why your leopard gecko is opening his mouth extremely wide. We will also share the best solutions to ensure your scaly companion is happy and healthy.

Let’s begin!

Mouth Gaping vs. Yawning in Leopard Geckos: What’s The Difference?

Mouth gaping in leopard geckos looks pretty much like a yawn pose. It’s easy to confuse the two, especially if you are new to gecko parenting. So, is your Leo gaping, or are you overthinking?

Yawning, like gaping, involves opening the mouth really wide. However, when yawning, your gecko will only open its mouth for three to five seconds. The pet will also look relaxed or relieved after the yawn.

It is common for geckos to yawn after an active session, satisfying sleep, or a tasty meal. Generally, yawning is harmless, and your scaly friend may even yawn for no apparent reason.

On the other hand, gaping is a long or excessive yawn. It involves keeping the mouth open for much longer, and the action is often accompanied by rapid movements and signs of anxiety or tension. Also, while the yawning action is quiet and graceful, gaping may occasionally involve a little squeaking noise typically caused by belabored gular pumping and gular fluttering.

Cause for concernHarmless action
Mouth remains open for continuous minutesMouth remains open for three to five seconds
Happens over five times in a rowHappens once or twice consecutively
May be accompanied by squeaking noisesQuiet and graceful
Accompanied by signs of anxiety or tensionCauses relief and relaxation

7 Possible Reasons Why Your Gecko’s Mouth Is Open

Gaping is a concern that needs your immediate attention. As a rule of thumb, you have reason to suspect gaping if a yawn lasts more than five seconds or you notice what seems like excessive yawning.

Although occasional gapping should not get you worked up, excessive gaping can be the bell for the following underlying issues.

1. Body Temperature Regulation

Leopard geckos are cold-blooded creatures that rely on external heat sources for thermoregulation. When raised as pets, creating a thermal gradient terrarium with a warm and cool end is crucial.

As reptiles native to arid grasslands and desert regions, leopard geckos thrive in enclosures that maintain a temperature of between 90 and 95°F (34°C) on the warm end and 75 to 80°F (24 °C) on the cool end. Mimicking the reptile’s natural environment can help keep your pet comfortable and healthy.

Unlike conventional furry pets that sweat, pant, or shiver when overheated, Leopard geckos move from place to place in search of cool spots. If your pet cannot find his thermal optimum, he will open his mouth ajar to promote accelerated heat loss.

Monitoring Temperatures inside the vivarium

Monitoring Temperatures inside the vivarium


The most probable reason your Leo is gaping is because he’s feeling too hot. You must remedy the issue quickly because overheating can cause lethargy, unresponsiveness, dehydration, and sleep deprivation in geckos.

First, temporarily remove your pet from the tank to determine why the enclosure is getting too hot. This should offer instant relief, and your scaly companion will likely close his mouth after a few minutes.

Next, check the settings on your heat sources, such as heat mats, ceramic heat emitters, or UVB lights. Inspect their power cords to rule out a short in the wiring, and double-check the settings on your thermostat.

Thermometers that stick to the sides of the inside of the gecko terrarium offer an easy way to monitor temperature changes within the tank. Ideally, the reading on your thermometer should match the thermostat’s temperature setting. If you notice a difference between the two, adjust your thermostat accordingly.

2. Choking

Another possible reason your gecko is gapping is because he’s choking on food. Healthy Leos can work up quite the appetite and may try chomping huge chunks of their feeder insects. Occasionally, things go south, and part of the exoskeleton, like a cricket leg, ends up stuck in the throat.

A Leo choking on food will look distressed. He will open his mouth severally after a meal and seem like he’s working toward regurgitating.

Gaping can help dislodge stuck food and flush it down the throat. The gecko may also shake its head frantically to pass down the stuck chunk or ease the discomfort.

Leopard Gecko Choking


There are three possible outcomes of a choking incident. The first and most probable is that your reptile will resolve the situation like a champ, meaning your intervention will be unnecessary. Another possible outcome is that the gecko will throw up, and you’ll find a barf in his tank.

The third and most improbable outcome is that you’ll have a life-threatening choking incident on your hands. If your Leo cannot push the stuck food down the throat or vomit, you’ll have to lend a hand to save your beloved pet’s life.

Here is what you have to do:

Unfortunately, the food obstruction may be so far down the throat that you cannot reach it with your tweezers without causing grave injury. In this case, you must be quick and get to the nearest vet.

If you dislike the idea of fishing inside your gecko’s mouth, we strongly recommend ensuring the feeder insects you provide are no more than half the size of your pet’s head. Helping out a choking gecko often poses the risk of causing accidental injury.

3. Environmental Stressors

Leopard geckos are docile creatures with a laid-back attitude. However, they can get stressed. Prolonged stress can impact their mental and physical well-being, making it crucial to identify and address the underlying problem.

Besides keeping the mouth open for extended periods, other signs of stress in Leos include the following:

As solitary creatures, the environment plays a significant role in dictating how a gecko feels mentally and physically. Nothing is as important to your scaly friend as ensuring his enclosure is of the right size and maintains the ideal temperature, lighting, and humidity.

Generally, even something negligible to humans, such as improper lighting, can cause stress in leopard geckos. These reptiles are also not great fans of too many changes in their tanks, especially if they happen too frequently.

Loud noises or lots of movement outside the tank can also cause stress because your Leo will constantly worry about being the next meal for a potential predator.

> Recommended Reading: 8 Signs to Tell Your Leopard Gecko is Happy & Healthy


The surest way to remedy stress in leopard geckos is to ensure they have a comfortable living environment.

Monitor the tank’s temperature and humidity and ensure the lighting is comfortable for your pet. Be sure to also keep up with proper hygiene practices to keep pests and diseases at bay.

Furthermore, ensure you place the gecko terrarium at a strategic spot.

Ideally, your gecko’s tank should be far from sources of loud and sudden noises. Choose a room where your pet cannot get spooked by the constant noises of honking cars, ringing phones, banging doors, stomping feet, or conversing people.

> Recommended Reading: Leopard Gecko Stress Signs & Common Causes

4. Defensive Stance

For a novice, it can be challenging to differentiate the signs of happiness and aggression in leopard geckos. It’s easy to assume your scaly friend is happy to see you if he charges at you while vocalizing and with the mouth wide ajar.

Sorry to burst your bubble, but geckos are not puppies, and this is not their way of showing joy.

Leopard geckos are gentle creatures that seldom show signs of aggression. However, they get defensive or bite if they feel threatened or want to be left alone.

When happy, leopard geckos make no sound at all. You may want to retreat and save your fingers if your scaly friend is gaping and making a high-pitched squealing or yelping sound. When taking a defensive stance, the reptile will also crouch low to the ground, his tail standing on end and moving in an “S” pattern.


Leopard geckos are loners. Although they can be social creatures, socializing is not high on their priority list. If your Leo shows signs of aggression, the best course of action is to retreat.

Staying off your pet’s turf will not hurt his feelings. Give the reptile space and interact only while feeding and cleaning the tank. Also, don’t make any sudden movements if you want to win your gecko’s trust.

In this case, patience is a virtue you must master through hook or crook.

5. Respiratory Tract Infection (RTI)

Sometimes, the underlying cause of gaping is a respiratory infection. RTI is a bacterial lung infection typically caused by poor husbandry. Although an infection can be caused by many issues, including poor feeding and improper hygiene practices, the most common cause of RTI is low temperatures and high humidity levels in the vivarium.

The ideal humidity level in a leopard gecko’s enclosure should range between 30 and 40%. The idea is to match the humidity levels in the reptile’s dry and semi-desert natural habitat. Exposure to higher humidity levels for longer periods can cause both respiratory infections and skin-related problems.

Besides gaping, other telltale signs of a respiratory tract infection include the following.


To remedy the situation, first check the tank’s temperature to identify and repair or replace any malfunctioning equipment. You’ll also need to use a digital hygrometer to monitor the humidity levels. Unlike analog hygrometer versions, digital models are easier to use and provide more accurate readings.

If the humidity levels are unsuitably high, here are a few tips to help you lower them.

Most importantly, you should consult a vet for proper diagnosis and treatment. Respiratory tract infections are treatable with antibiotics, but seeking timely treatment is crucial.

6. Mouth Rot

Unfortunately, your leopard gecko may keep his mouth open because of mouth rot. Also known as Infectious Stomatitis, mouth rot is a serious bacterial infection that can cause an immune system dysfunction and fuel other health problems, including digestive and respiratory issues.

If left untreated, mouth rot can infiltrate other body parts and impact various other body functions before causing death. The typical symptoms of the disease include:

The leading causes of mouth rot include poor hygiene, improper environmental conditions, trauma, parasites, stress, and poor nutrition. Generally, many issues can contribute to the development of the disease because it is caused by bacteria commonly found in the reptile’s mouth.

Leopard Gecko Mouth Rot


Mouth rot is highly infectious, and you must separate the ailing reptile from its cage mates. The disease is also highly aggressive, making it crucial to consult a vet immediately.

Treatment typically involves a course of antibiotics. Your vet will also use a local antiseptic to clean infected areas to accelerate healing. In severe cases, a surgical procedure may be necessary to help remove any necrotic or dead tissue.

Most importantly, you must address the underlying cause of mouth rot. This is relatively easy, and you merely need to ensure you uphold proper husbandry practices.

First, clean the cage and create a routine to maintain sanitary living conditions. You must also check the temperature and humidity of the vivarium routinely and address any concerns before damage happens.

7. Metabolic Bone Disease(MBD)

Leopard geckos need UVB lighting for proper calcium metabolism and vitamin D formation. The lack of it causes an improper balance of nutrients, minerals, and vitamins that make up the bones, leading to Metabolic Bone Disease.

MBD arises when the body has low calcium, an abundance of phosphorus, and insufficient vitamin D3, which helps regulate calcium absorption.  The ailment is characterized by the demineralization of bones, leading to fractures, done deformation, mandibular softening, paralysis, general weakness, and death if left unattended.

Your Leo can involuntarily keep the mouth open because of mandibular softening, also called rubber jaw. The symptom is characterized by unusual flexibility of the lower jaw, making it challenging for your scaly friend to keep his mouth shut.


Although MBD is debilitating and incurable, it is also highly preventable. To prevent the disease, dust the feeder insects with a calcium supplement before each meal. Also, dust the feeder insects with a multivitamin supplement rich in vitamin D3 twice monthly.

Moreover, ensure the terrarium setup has a 5.0 UVB bulb. Proper lighting is imperative to keep your gecko’s internal clock ticking correctly.

If you suspect your Leo has MBD, immediately talk to a reptile veterinarian. While treatment is unavailable, a vet can offer viable remedies to ease the pain and slow down the progression of the disease.

Final Thoughts

Although a myriad of concerns can cause gaping, this act is often just your pet’s way of cooling his body down faster. It’s an evolutionary behavior that is an innate part of reptilian thermoregulation.

Moreover, it’s common for Leos that dislike handling to open their mouth wide before they bite you. The gapping act is their way of warning you to keep off. Still, it’s best to observe your pet’s body language and living environment to identify and address gapping caused by serious concerns like choking, poor husbandry, health issues, or environmental stressors.

Frank Miller

Frank Miller is the Founder of Lizard Advisor and owns several pet lizards, from leopard geckos, bearded dragons, crested geckos, chameleons, and others. The mission of this website is to make owning a pet lizard very easy for everyone, but mostly beginners. And each year, he continues to help more people learn more about lizard care and much more.