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Sick Hamsters: Signs of Fungal Infections and Treatments

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Whitney is a hamster parent. She hates to see her furry friends suffer and enjoys educating others of best husbandry practices.

Signs of and Treatment of Fungal Infections in Hamsters

Signs of and Treatment of Fungal Infections in Hamsters

Can Hamsters Get Sick From Fungal Infections?

Hamsters are generally pretty clean animals, but they can only do so well when they're not being taken care of. Even if they can kick out all of their old bedding, they can't put in fresh bedding, disinfect their cage, or replace leaking water bottles with new ones.

Taking care of a hamster is the owner's responsibility, and that responsibility cannot fall solely on a child, either. As for fungal infections and fungus growing in the hamster's cage, it's paramount that you clean the cage!

Where Can Fungus Grow in a Cage?

Generally, the fungus will grow where there is moisture that gets trapped and doesn't dry out. If the moisture is there long enough, it will grow in your hamster's cage. It is important to realize that it is your fault for not cleaning the cage—it's not that the hamster is "too messy" in any way. The fungus can be deadly, so you need to be careful.

How Often Should I Clean My Hamster's Cage?

Weekly cleanings will prevent fungus growth. Simply remove the bedding, disinfect the cage, and replace old bedding with new bedding.

What Types of Fungal Infections Do Hamsters Get?

The most common fungal problem that hamsters might develop is ringworm, which is also very common in children and other animals as well. Aspergillus fungus is another fungus that may hinder your hamster's health.

A Guinea Pig With Ringworm

A Guinea Pig With Ringworm

Ringworm in Hamsters

Ringworm is a more common type of fungal infection in hamsters. It is very contagious and can be passed to other animals and people.


When moisture gets trapped in cage bedding, the fungus can grow. With the increased use of plastic cages that are partially to fully enclosed, the risk of moisture buildup is greater.

Signs of a Ringworm Infection

  • Circular patches of hair loss
  • Dry, scaly skin
  • Skin that illuminates under a Wood's lamp


Generally, the hair around the ringworm will be clipped and the infected area will need to be bathed with a povidone-iodine shampoo as directed by a veterinarian. Some veterinarians may just prescribe an anti-fungal cream that would need to be applied to the area.

The cage needs to be fully disinfected and ventilation should be improved, which may call for a new cage altogether. Never introduced/expose unfamiliar animals to each other without observing a healthy quarantine period or having a proper vet visit first.


Ensure that the hamster cage is well-ventilated. Keep the enclosure clean. Replace leaking water bottles.

Aspergillus Fungus in Hamsters

Most people clean out their hamster cage regularly, so Aspergillus isn't as frequent as ringworm, but it does have more severe health consequences.


A dirty cage will cause Aspergillus to grow. It also tends to grow in the bedding in the area where the hamster potties the most. Corn cob bedding is prone to developing Aspergillus, as it seems to grow faster here than in any other bedding. It will also grow on fruits and food that has been left in the cage for way too long.


Once it starts to grow, the fungus appears white and then turns black. When it's black, the fungus releases airborne spores which can then impact your hamster's health. You'll start to see signs of illness in your hamster as they begin to breathe in the deadly spores.

Signs of a Fungal Infection

  • Lethargy
  • Breathing problems
  • Wheezing
  • Blood in urine
  • Inflamed skin
  • Chronic diarrhea


If you see fungus in your hamster's cage and start to see signs of health problems, you'll want to clean out the tank as soon as possible and see a vet who will diagnose and treat your hamster. A vet will treat the hamster with antibiotic and anti-fungal medication.


The best way to prevent fungus from growing in your hamster's home is to clean the enclosure. Clean the bedding once a week with a safe, non-toxic disinfectant. Also, make sure that you remove any fresh food daily.

More Common Illnesses in Sick Hamsters

This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.

© 2010 Whitney


Stacey on August 25, 2011:

My hamster is 2 and a half years old. He's always been in good health until a number of months ago when I noticed his eyes were crusty/sleepy for three days on the trot. I bathed them each day so he could open them and booked him in for an appointment with the vet. The crustiness around the eyes stopped, but his skin on his face, mainly around his whiskers got flakey and he has some hair loss around the region. He was treated for mites, my first suspicion which the vet agreed with, but after two courses of treatment and complete change of cage materials there was not really any improvement. I requested lab testing and after a loooong wait they concluded that it was fungal, but they've offered no treatment. It's not ringworm. His cage is cleaned thoroughly weekly. Fresh food and water and treats (including the occasional fresh fruit/veg and roast chicken) so I just don't know what to do. He's a wonderful little man and I want him to be comfortable in his old age. He's never been able to clean himself as well as other hamsters because he was born without back feet and can't really balance very well sitting. Can you recommend or suggest safe treatments to try to make my little guy happier and healthier?

Annoymous on July 19, 2011:

Does the fungus spread to humans?