Yellow Fungus Disease (YFD)/Nannizziopsiosis

*Note – this is written from the perspective of bearded dragons as being the main species affected by YFD.  However, there are other documented cases of iguanas, crocodiles, and other species contracted this condition.


In my experience, yellow fungus disease is an aggressive, highly infectious, and flesh-eating fungal disease that has a high fatality rate.  Baby beardies appear to have less chance of recovery than their juvenile and adult counterparts as they have not built up enough strength in their bodies and immune systems yet.   I have found that symptoms of YFD can affect an entire clutch within the same week, although each individual may display symptoms at different rates during that first week.

When I purchased Flo from a well-known pet store in the USA in 2008, I noticed that several of his cage-mates appeared lethargic.  I did not know about YFD at this time.  However, when I phoned the store back and explained what was happening to Flo, I was told it affected the entire clutch and that many of them were undergoing treatment.  Further, after my vet discovered that it was YFD (even though I already knew it after some brief research), she noted that many pet stores were bringing in entire clutches that had the disease within that same month.  Because of this, I believe that conditions at large-scale breeders at this time may have been a reason why so many  pet store beardies contracted this disease.

Without the presence of symptoms, it would be very difficult to know whether or not your bearded dragon has yellow fungus.


  • Yellow, patchy spots on the skin (these will start to appear all over the body if left untreated)
  • Lethargy
  • Loss of appetite
  • Necrotic or swollen appendages (such as a black-colored and swollen toe)
  • Blister-like spots on the body (this is when the skin where the yellow, patchy spots are turn to dead skin and become moist and from thick and dry with adhered dead skin to moist and blister-like in appearance.)
  • Blister-like spots begin to slough off or become necrotic

Unfortunately I did not have the foresight to take pictures of Flo’s yellow patches and blisters.  I did, however, get pictures of some of his necrosis.

Flo's Tail and Toe Necrosis (a Yellow Fungus Disease Symptom)

Flo's Tail and Toe Necrosis (a Yellow Fungus Disease Symptom)

Flo's Necrotic Tail (a Symptom of Yellow Fungus Disease)

Flo's Necrotic Tail (a Symptom of Yellow Fungus Disease)

Flo's Necrotic Toe Tip (a Yellow Fungus Disease Symptom)

Flo's Necrotic Toe Tip (a Yellow Fungus Disease Symptom)



If your bearded dragon ever exhibits any symptoms of YFD, take him or her to the vet immediately.  As mentioned above, this is a highly contagious and aggressive condition that often results in fatality.  It can be treated in a vet’s care with oral medicine such as itraconazole (this medicine can cause liver toxicity so be cautious while using it) and applying topical antifungals to blisters and necrotic or swollen spots.  Furthermore, given that your beardie will likely be lethargic and have loss of appetite by this time, you will need to feed Oxbow Critical Care/Carnivore Care as prescribed by your vet.


Be sure that your vet has the proper experience with bearded dragons to diagnose YFD.  Antibiotics are known to exacerbate the condition.  In my experience with my bearded dragon, Flo, the vet thought that he had an infection despite my suggestions that it was YFD.  She prescribed an oral antibiotic and admitted when she realized, later, that it was YFD that it actually worsened Flo’s condition. 

(By Ash on behalf of Reptile-Parrots Forum and Chris and Ash’s Explorations of Exotic Species and Average House Cats wordpress blog )


6 responses to “Yellow Fungus Disease (YFD)/Nannizziopsiosis

  1. Pingback: My First Bearded Dragon Experience: Flo, the Baby Beardie « Chris and Ash's Adventures & Explorations of Exotic Species and Average House Cats

  2. Thanks so much for the info. My iguana, Nebune, unfortunately has contracted YFD, and my vet told me that the only way he could have gotten it would be by coming into contact with another infected reptile. Nebune hasn’t been around iguanas or other reptiles since he was born, six years ago. The infection started in his eye, and has progressively moved along the left side of his face. Booney also has a couple patches on his right rear leg. My vet mentioned Voricanozole, which can cost thousands of dollars. I will mention Itraconazole to my vet. She is currently looking into alternatives. I hope it’s not too late. Thanks for your dedication.

    Best Regards,


    • Max, I am so sorry to hear this. I must have missed this comment as well. I hope that all worked out well with Nebune. The good news is that older, healthy reptiles have a better chance of fighting it off. There is also another fungus disease that iguanas get called black fungus or blister disease, however, and I am wondering if this is what it is. Do you have him on any sort of particulate substrate? Check out this thread which has more information on it:

  3. God luck with Nebune, its a really tough diseases to treat! If you had a chance to take pics of his addected skin, tag the photos and post on the internet, we hope to encourage readers to share their own photos so that identifying reptile diseases will be a much quicker process!

  4. Hello. So, I have two bearded dragons, a male and female. They are both around a year old or more. I’ve noticed something quite suspicious. It mainly started with my male, Eko. I thought he was going through some shedding problems, so I went on trying to help that, but it has been awhile now. And recently I have noticed his scales have been off a little bit. For instance, yellow-like, blotchy spots… darkened scales, scab-like areas, etc. Those things are mostly around his lower body. Not only has he been worrying me, but the female seems to have a little, awkward spot on her belly, as well. The female is kept with the male. I did some research, recently, to try and figure out what could be going on and stumbled upon YFD. I didn’t quite know of YFD before. I Googled pictures of bearded dragons with the disease and such… and my dragons are displaying similar symptoms and whatnot. I pretty much know how to treat them now, I suppose, but I’d like to have some “reptile lovers” help me out on this one, give some input. I have never dealt with this before and have about a decade or more of experience with reptiles and such, espescially bearded dragons. One problem I’m having is, this city doesn’t really have a vet center dedicated to reptiles, specifically. We have one vet here that works on an assortment of creatures, but almost everytime I’ve gone to them, it seemed as if I knew what the hell I was doing more than they did. Anything will help. Thank you.

    • Hi, I understand what it’s like with people who call themselves “exotic” specialists. I don’t think there is a home remedy for YFD and it’s important to treat it early. It’s probably best to bring the information and articles with you to this vet and just get them to prescribe the correct medication for you. What city are you located in? I personally bring all my reptiles to UPenn Ryan Veterinary Hospital because their exotics team is phenomenal. This site has a veterinarian listing: and links to other listings. Hope all goes well.

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