It’s always concerning when a hamster starts to bite itself. As this isn’t for dominance or defensive reasons, you may be puzzled by why the hamster has become self-destructive.
If the hamster is biting and scratching, it likely has a health condition, like an allergy, injury, mites, stress, or grooming difficulties. If this behavior isn’t stopped, its quality of life will suffer.
What Causes Hamsters To Bite Themselves?
Here are the main reasons for this destructive behavior:
Fur Mites
If a hamster constantly bites and scratches, it likely has fur mites. A hamster with fur mites will exhibit the following symptoms:
- Excessive scratching leads to reddened skin.
- Loss of fur in the affected areas.
- Nervousness.
- Biting any exposed, scaly skin.
- Difficulty walking.
Mites can affect the hamster’s behavior, potentially making it more active than usual.
Examine the skin around the ears to tell if a hamster has fur mites. Often, mites appear like tiny black dots on the fur. Further, the skin around the ears, nose, and feet will also appear reddish and inflamed.
Hamsters with fur mites will keep biting themselves, trying to get rid of the irritation caused by the mites.
How to Get Rid of Fur Mites in Hamsters
A vet will perform tests to determine the following:
- Type of mites.
- The extent of the infestation.
- Appropriate treatment.
Usually, acaricides are the most effective way of treating mites in rodents. That said, mite treatment won’t be effective without sanitizing the hamster’s living space.
Start by washing the hamster’s toys, accessories, food, and drinking bowls with soap and hot water. After that, spray the cage’s interior with an insecticide or acaricide solution.
Stress Levels
According to the National Center for Biotechnology Information, environmental changes can stress pet hamsters. At times, stress can affect their behavior.
High stress in hamsters leads to destructive behaviors, such as cage rage and self-mutilation.
The former is where hamsters hit their heads against their cages in random moments of wild frenzies, while the latter is characterized by self-biting.
If a pet hamster is stressed, it may seek relief and excitement in other ways, like biting off its fur and skin. The latter is uncommon and is mostly observed in hamsters dealing with stress and depression.

Sources of Stress in Hamsters
The following are the main stressors:
Overcrowding
Hamsters, especially Chinese and Syrian hamsters, are loners.
If you have multiple hamsters in one cage, the more introverted ones may be disoriented by the increased competition for food and lack of space, leading to depression.
The change in mental state may lead the hamsters to bite off their fur as a coping mechanism.
Social Defeat
Hamsters prefer to be left alone, so they often get into territorial fights.
Unsurprisingly, the University of Tennessee found that hamsters who lose fights get so stressed that some go into complete social avoidance.
They occasionally lick the injuries they’ve sustained during fights, which may make you think they’re gnawing themselves when you see blood.
However, some defeated hamsters self-mutilate., especially males.
Isolation
Although hamsters are mostly solitary creatures, extended periods of isolation can be mentally devastating. According to Neurobiological Stress, the key effects of social isolation include:
- Reduced body weight.
- Increase in aggressive behavior.
- Changes in dopamine signaling in the brain.
During these periods of isolation, hamsters may inadvertently bite their fur for entertainment.
Stress Prevention Tips
Keeping the hamster happy reduces stress levels. To this end, here are ways to assist:
Attention
Despite being loners, hamsters also like affection and socialization with their owners. So, play with your hamster every few days. Ideally, don’t interfere with its space, but talk to it whenever possible.
Enrich the Cage
A boring environment is a common cause of stress, so make the cage more interesting.
Aside from hideouts and running wheels, get toys and accessories like hamster hammocks, tunnels, chewing toys, and play bridges. These will keep the hamster entertained and let it exercise regularly.
Allergies
Hamsters can develop allergies that make them itchy, extending to the point where they can’t stop scratching themselves. The most common allergy triggers include:
- Cleaning solutions.
- Artificial colorings and sweeteners.
- Fecal dust.
- Cigarette smoke.
- Bedding.
Determining the type of allergen affecting a hamster involves trial and error. For example, you can remove certain seeds or nuts for a few days to see if the scratching stops.
Existing Injuries
Hamsters can get into fights, climb on objects, and play with sharp items. All these activities can lead to injuries that may take time to heal.
It’s normal for hamsters to lick their wounds, sometimes throughout the healing process. It may seem like the hamster was biting itself when the wounds were caused by something else.
Small wounds heal by themselves once the blood clots, but a trip to the vet will be necessary for larger cuts. A lack of timely intervention can leave the hamster susceptible to bacterial infections.
Conduct body checks on the hamster, paying closer attention to the areas it is constantly biting or scratching. If you observe any signs of cuts or blood, consult a vet.
Grooming
If you’re new to hamsters, you may be confused by their grooming habits. For instance, it may seem that the hamster is scratching itself while, in reality, it’s grooming itself.
If you’re concerned the hamster is scratching itself excessively, check the area for scars. Most of the time, you’ll find that it was just cleaning its fur.