Pet owners beware! Hazards of using topical Calcipotriol and Flourouracil.

What information do we need to give patients who are prescribed 5-Fluorouracil? What are the potential problems that our canine friends can develop when exposed to this cream?
Here are a few references that may be helpful.
1. A dog’s life: an unfamiliar and lethal side effect of topical 5-fluorouracil. Clinical Exp Dermatology 2018;43:732.
2. Toxic Effects of Fluorouracil Cream Ingestion on Dogs and Cats. Arch Dermatology 2010;146:1195-6.
3. 5-Fluorouracil Toxicosis in the Dog. Journal of Veterinary Internal Medicine 1990;4:254-7.
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[@MarciaSvitko]

This information needs to be given to dermatologists. I mentioned this to mine and refused to use it twice a day because I have a lap cat that likes to kneed my cheeks. She seemed surprised about the toxicity to pets or just did'nt care to inform me of this. Happy to find this site!

[@DiscoverDermatology]

You are right that not many are aware of this side effect of Efudix, including dermatologists! Glad you found the information helpful!

[@RohanYesudian]

Good example of the one health concept!

[@DiscoverDermatology]

What is the one health concept?

[@RohanYesudian]

@@DiscoverDermatology One Health is "the collaborative efforts of multiple disciplines working locally, nationally, and globally, to attain optimal health for people, animals and our environment"

[@DiscoverDermatology]

@@RohanYesudian Interesting! Thanks Ro.

[@sharonknecht9521]

Thank you so much. I started using Flourouracil about 3 weeks ago and use gloves to apply. I then throw in the trash can in bathroom that is low to the ground…this is so important to know and agree with another comment stating it should be on the label as black box warning. THANK YOU!!!

[@DiscoverDermatology]

You are welcome, glad it was helpful! This is a topic that many dermatologists are unaware of as well.

[@MonishaMadhumita]

Such an important piece of information! Going to pass on this info to my colleagues in residency.Thankyou, Dr.Yesudian! (PS: Your voice is incredibly soothing !)

[@DiscoverDermatology]

Thanks for your kind words Monisha. I came across this information quite recently, so I was surprised that such a practical bit of info is not made known to us by the manufacturers of these creams.

[@vinodmiriyala]

Doc, this is a public service announcement. Thank you so much on the toxicity.

[@DiscoverDermatology]

You are welcome! It’s a bit of information that I became aware of recently and not many dermatologists know either.

[@rabinambi8498]

Excellent point Divakar...A completely new one for me! Is there any enzymatic deficiency in these dogs as considering the wide spread world wide usage of efudix and the universal presence of dogs in elderly people home and the seeming lethal dose at minimal exposure...seems to be less common than expected....We know that enzymatic deficiency in humans causes severe reactions within 1 or 2 days of usage ..Forgot the name of enzyme! Thanks for this interesting lecture . Maybe time to write to the manufacturer and have a warning on the box ...? Rabi Nambi

[@DiscoverDermatology]

Thanks Nambi, you are right I think. We know that dickofenac is toxic to vultures and may be to dogs too because of a faulty enzymic conversion to a more toxic product. So that may explain the toxicity of 5 FU and calcipotriol too. Well taken point. Shall I just write to the manufacturers of 5FU and calcipotriol?

[@rabinambi8498]

@@DiscoverDermatology Agree ..Would be good to highlight this and copy the RSPCA ! That will grab the attention of manufacturers!

[@DiscoverDermatology]

@@rabinambi8498 Good point Nambi, will look into the insert first to see what the manufacturers have mentioned at present.

[@dizzzie612]

Thanks for this information. I am currently using flourouracil on my face and backs of both hands - places my dogs loves to lick. I hadn’t considered that some of this cream could be ingested when he does so …I will be much more aware in the future.

[@DiscoverDermatology]

Glad it had useful information. I got to know this information just a couple of years ago. I think most dermatologists are not aware of it either!

[@dizzzie612]

I will certainly be discussing this info with my skin cancer specialist. Thanks again for sharing these details 👍

[@monicajoseph4163]

Very useful

[@DiscoverDermatology]

Thanks a lot Moni!

[@johnK85086]

So how is it not toxic for.humans then?!

[@DiscoverDermatology]

Our body is able to metabolise it to a certain extent but canines are not able to. Thats is the reason it is toxic to them.