Ivermectin Effective Against New World Screwworms Larval Stages (L1, L2, L3)
As New World screwworms emerge in Texas and New Mexico, the evidence suggests ivermectin may be one of the most effective defenses in both animals and humans.
Nicolas Hulscher, MPH
Jun 08, 2026
FDA Issues Emergency Use Authorization for Over-the-Counter Injectable Drug to Prevent New World Screwworm in Cattle
February 5, 2026
Today the U.S. Food and Drug Administration issued an Emergency Use Authorization (EUA) for Ivomec (ivermectin) injectable solution against New World screwworm (NWS). The agency has concluded that based on the scientific evidence available, it is reasonable to believe that Ivomec may be effective for the prevention of infestations caused by NWS larvae (myiasis) in cattle when administered within 24 hours of birth, at the time of castration, or when a wound appears, and the known and potential benefits of the product outweigh its known and potential risks.
Ivomec is not for use in female dairy cattle producing milk for human consumption and calves that will be processed for veal. The slaughter withdrawal period for cattle is 35 days.
This EUA will be effective until it is revoked or the HHS Secretary terminates the declaration that the potential public health emergency presented by NWS justifies the emergency use authorization of animal drugs for NWS.
Ivomec is available over the counter without a prescription. Producers are responsible for using Ivomec in accordance with the product labeling and fact sheet.
To reduce the risk of antiparasitic resistance and preserve drug effectiveness against both NWS and other parasites, producers are encouraged to use antiparasitic drugs like Ivomec only when medically necessary and as part of a comprehensive parasite management strategy.
The FDA has previously approved Ivomec to treat and control other parasites in cattle, swine, reindeer and American bison.
Ivomec is sponsored by Boehringer Ingelheim Animal Health USA, Inc. based in Duluth, Georgia.
Related Information
Freedom of Information Summary: Ivomec (EUA 006689)
Letter of Authorization: Ivomec (EUA 006689)
Fact Sheet: Emergency Use Authorization of Ivomec (ivermectin) Injection
Ranchers already use ivomec to deworm their cattle, in spring and fall. Using that as well as closer attention to livestock and we should be just fine. We didn’t have ivermectin the last time the screwworm was in the US cattle supply (there was a short outbreak in 2016 in Florida in the deer population and it was gone by 2017).
Edit: Anyone screeching about this topic is just fearmongering. It only spreads through open sores and navels that are fresh in newborn calves. Ranchers know how to deal with this because we already deal with open sores and doctor navels in newborn calves.
Been taking Ivermectin for 2 years. One week every month. Feel flu, I start it and feel great in less than 24 hours. My entire family uses it.
I was diagnosed with aggressive form of breast cancer and a non aggressive in right breast 3 months ago. Began taking 100mg Menbendazole with the 12mg Ivermectin. 4 days on, 3 off.
Masectomy of right breast. Hospital pathologist could not find any trace of the aggressive double negative tumor. The ither was tajen care of by removing the breast. They were going to do chemo and radiation following masectomy but I dont have to now. My oncologist had his pathologist team check the breast tissue again and can find nothing. I think it is my miracle from God. I can't say it works for everyone and maybe not in the small doses I was using but it's worth trying.
Be aware that neither ivermectin nor fenben cover ALL parasites individually & that many recommend alternating between the two for full coverage. They say you're not supposed to take both simultaneously as that can cause liver and kidney damage. Be sure to do your homework...
Yeah, like my cat with hyperthyroid whose meds for that helped to destroy her kidneys. Can we please move on to the part where we don't need pharmaceutical anything?
Yeah, like my cat with hyperthyroid whose meds for that helped to destroy her kidneys.
Isn't it ironic that vets use the same BS when saying that while using Felimazole to help in reducing a cats T4 levels that it often leads to the finding of an another hidden disease. CKD
Most of them (vets) are just another wing of the big pharma pill pushers with an excuse/coverup for all the side effects that they claim is status quo.
FWIW, if your cat is still with you, I highly recommend Kidney Support Gold for cats.
She turned 18 last month, and we'd been giving her subcutaneous fluids for 40 days when her body said she'd had enough of this life (2 weeks ago). The regular vet started her on Methimazole many long years ago, but she'd been treated by a holistic vet for the last 6 years of her life. Who knows how different it would have been if the holistic vet was the one who discovered her heart murmur...
But rest assured she knew she was very much loved and cared for as best as humanly possible thanks to you.
Living to 18 is a pretty good run especially for a cat (family member) with those underlying health conditions.
I've been there a few times over the years and currently have an 16yo cat who's going through the same exact thing complete with heart murmur & anemia.
It's definitely a roller coaster ride as you already know.
Good days, not so good days.
It sucks, but I'm doing all I can to keep the old boy going as I can clearly see that he's not giving up yet.
It gets pretty expensive with all the special foods that they hate (I gave up on buying that overpriced bland shit), and now just give him his life long favorites and follow it up with a phosphorus binder.
And of course the damn meds that I agree only cause other serious issues just like in humans.
Out of curiosity how long was your kitty on that Methimazole and at what dose?
5mg twice a day I'm guessing.
Anyway once again I'm sorry for your loss as I know the pain that losing a dear four legged family member brings.
2.5 mg twice a day for quite a while...7 years? We switched to a holistic vet who put her on raw chicken, like 6 years ago, and a blood test eventually showed the methimazole wasn't working as well as she needed it to. The vet had us add Wen Dan Tang (1/8 tsp 2x/day) to her meds. Chinese herbs are not tasty, so for quite a while, I got that 1/8 tsp into 3 number 4 capsules. Yep. I did that. I forget when the CKD showed up. It's hard, And when our beloveds leave the Earth plane, I tell myself I won't do it again. Yeah, right. We're set to meet up with a cat rescue on Saturday to see if the kittens we saw online are OUR kittens. Life without cats...I really can't imagine...
Thank you for your kind message. And in case you're interested, it was too late for us, but I did get a Spooky2 X Pro rife machine to help her. I'm using it on my daughter and myself now.
I'm so sorry...it brings tears to my eyes to hear. Our loss is only a month or so in the past, so I get it. Curled up on my arm atm is one of 3 sister kittens from a rescue. I wanted to wait, but these are the right ones for our family members to come back to us...
And I know how that sounds, but we've been in touch with an animal communicator who happened to be at our friend's house where we stayed after a house fire in 2024. One of our cats perished in that fire (from smoke), and he wanted to come back to us.
Anyway...your Thomas is with you still, just in a different form.
Ivermectin Effective Against New World Screwworms Larval Stages (L1, L2, L3) As New World screwworms emerge in Texas and New Mexico, the evidence suggests ivermectin may be one of the most effective defenses in both animals and humans. Nicolas Hulscher, MPH Jun 08, 2026
https://www.thefocalpoints.com/p/ivermectin-kills-new-world-screwworms
Great post! Thanks chick! 👏
I found this also:
FDA Issues Emergency Use Authorization for Over-the-Counter Injectable Drug to Prevent New World Screwworm in Cattle
February 5, 2026
Today the U.S. Food and Drug Administration issued an Emergency Use Authorization (EUA) for Ivomec (ivermectin) injectable solution against New World screwworm (NWS). The agency has concluded that based on the scientific evidence available, it is reasonable to believe that Ivomec may be effective for the prevention of infestations caused by NWS larvae (myiasis) in cattle when administered within 24 hours of birth, at the time of castration, or when a wound appears, and the known and potential benefits of the product outweigh its known and potential risks.
Ivomec is not for use in female dairy cattle producing milk for human consumption and calves that will be processed for veal. The slaughter withdrawal period for cattle is 35 days.
This EUA will be effective until it is revoked or the HHS Secretary terminates the declaration that the potential public health emergency presented by NWS justifies the emergency use authorization of animal drugs for NWS.
Ivomec is available over the counter without a prescription. Producers are responsible for using Ivomec in accordance with the product labeling and fact sheet.
To reduce the risk of antiparasitic resistance and preserve drug effectiveness against both NWS and other parasites, producers are encouraged to use antiparasitic drugs like Ivomec only when medically necessary and as part of a comprehensive parasite management strategy.
The FDA has previously approved Ivomec to treat and control other parasites in cattle, swine, reindeer and American bison.
Ivomec is sponsored by Boehringer Ingelheim Animal Health USA, Inc. based in Duluth, Georgia.
Related Information
SOURCE: https://www.fda.gov/animal-veterinary/cvm-updates/fda-issues-emergency-use-authorization-over-counter-injectable-drug-prevent-new-world-screwworm
Ranchers already use ivomec to deworm their cattle, in spring and fall. Using that as well as closer attention to livestock and we should be just fine. We didn’t have ivermectin the last time the screwworm was in the US cattle supply (there was a short outbreak in 2016 in Florida in the deer population and it was gone by 2017). Edit: Anyone screeching about this topic is just fearmongering. It only spreads through open sores and navels that are fresh in newborn calves. Ranchers know how to deal with this because we already deal with open sores and doctor navels in newborn calves.
Been taking Ivermectin for 2 years. One week every month. Feel flu, I start it and feel great in less than 24 hours. My entire family uses it. I was diagnosed with aggressive form of breast cancer and a non aggressive in right breast 3 months ago. Began taking 100mg Menbendazole with the 12mg Ivermectin. 4 days on, 3 off. Masectomy of right breast. Hospital pathologist could not find any trace of the aggressive double negative tumor. The ither was tajen care of by removing the breast. They were going to do chemo and radiation following masectomy but I dont have to now. My oncologist had his pathologist team check the breast tissue again and can find nothing. I think it is my miracle from God. I can't say it works for everyone and maybe not in the small doses I was using but it's worth trying.
Be aware that neither ivermectin nor fenben cover ALL parasites individually & that many recommend alternating between the two for full coverage. They say you're not supposed to take both simultaneously as that can cause liver and kidney damage. Be sure to do your homework...
Found this in the wild
Yeah, like my cat with hyperthyroid whose meds for that helped to destroy her kidneys. Can we please move on to the part where we don't need pharmaceutical anything?
Isn't it ironic that vets use the same BS when saying that while using Felimazole to help in reducing a cats T4 levels that it often leads to the finding of an another hidden disease. CKD
Most of them (vets) are just another wing of the big pharma pill pushers with an excuse/coverup for all the side effects that they claim is status quo.
FWIW, if your cat is still with you, I highly recommend Kidney Support Gold for cats.
https://www.amazon.com/Pet-Wellbeing-Kidney-Support-Natural/dp/B01N7VZQZW/ref=sr_1_1_pp?crid=JLZE0E8QNZ5M&dib=eyJ2IjoiMSJ9.Xw4dZMPo0utJCirpTlF1K7fprPyMflr-p6E4WhX5UTk51hjme7_5PhdMa1bccYEFXsn5eHfgltvO5megMWDTBC8tu6Fj9q7mP6eNmCovgLpugK4prWeYM9OkOT6QlQcgyoD34IrCaEhJGBd-7GlOzCJVsK4uwBJV10guMS2KqPdgDS6ahQJxauajP8luvWpTDxKNnvaXSIS1eZKF_DhetOUyC0Lege__amVTQbCSU19q6mA8UErL6pvZnPiFQqLu_j1y35g2C2oD4A5Fu1wmZ6zRVNwTYpCWdOrNTdLQym0.ivxcJGnharu2UCHgbxRBNKhjOJ5fdRMFrdCrLALl1nY&dib_tag=se&keywords=kidney%2Bgold%2Bfor%2Bcats&qid=1781041993&sprefix=kidney%2Bgold%2Bfor%2Caps%2C192&sr=8-1&th=1
She turned 18 last month, and we'd been giving her subcutaneous fluids for 40 days when her body said she'd had enough of this life (2 weeks ago). The regular vet started her on Methimazole many long years ago, but she'd been treated by a holistic vet for the last 6 years of her life. Who knows how different it would have been if the holistic vet was the one who discovered her heart murmur...
Your kindness is appreciated.
I'm so sorry to hear that.
But rest assured she knew she was very much loved and cared for as best as humanly possible thanks to you.
Living to 18 is a pretty good run especially for a cat (family member) with those underlying health conditions.
I've been there a few times over the years and currently have an 16yo cat who's going through the same exact thing complete with heart murmur & anemia.
It's definitely a roller coaster ride as you already know.
Good days, not so good days.
It sucks, but I'm doing all I can to keep the old boy going as I can clearly see that he's not giving up yet.
It gets pretty expensive with all the special foods that they hate (I gave up on buying that overpriced bland shit), and now just give him his life long favorites and follow it up with a phosphorus binder.
And of course the damn meds that I agree only cause other serious issues just like in humans.
Out of curiosity how long was your kitty on that Methimazole and at what dose?
5mg twice a day I'm guessing.
Anyway once again I'm sorry for your loss as I know the pain that losing a dear four legged family member brings.
They aren't just pets to many of us....🐈🐈⬛
2.5 mg twice a day for quite a while...7 years? We switched to a holistic vet who put her on raw chicken, like 6 years ago, and a blood test eventually showed the methimazole wasn't working as well as she needed it to. The vet had us add Wen Dan Tang (1/8 tsp 2x/day) to her meds. Chinese herbs are not tasty, so for quite a while, I got that 1/8 tsp into 3 number 4 capsules. Yep. I did that. I forget when the CKD showed up. It's hard, And when our beloveds leave the Earth plane, I tell myself I won't do it again. Yeah, right. We're set to meet up with a cat rescue on Saturday to see if the kittens we saw online are OUR kittens. Life without cats...I really can't imagine... Thank you for your kind message. And in case you're interested, it was too late for us, but I did get a Spooky2 X Pro rife machine to help her. I'm using it on my daughter and myself now.
May your kittyboy live long and prosper.
I had to put my buddy down about 24 hours ago..😪
There will never be another one like Thomas.
This one stings like I've never been stung before.......
I'm so sorry. He was your soul kitty💖
I'm so sorry...it brings tears to my eyes to hear. Our loss is only a month or so in the past, so I get it. Curled up on my arm atm is one of 3 sister kittens from a rescue. I wanted to wait, but these are the right ones for our family members to come back to us... And I know how that sounds, but we've been in touch with an animal communicator who happened to be at our friend's house where we stayed after a house fire in 2024. One of our cats perished in that fire (from smoke), and he wanted to come back to us. Anyway...your Thomas is with you still, just in a different form.
Without a doubt, we will ALL inevitably reach that part when our number is called...
u/#catdance
My vision is more like, in our lifetime...
It's a personal choice - you do the best you can.
It's a LOT of work eating clean & nutrient dense foods consumed on time, at the right time of day etc.
It can be done, but it takes dedication & preparing and packing your own food of you leave home on a trip etc.
The HERD will never get on track in our lifetime - It's a very personal, individual thing.
As far as doctors and care go, you have to seek out alternatives. I haven't gone to a medical doctor for anything in 35 years.
Again, not easy, not popular, but doable. Learn applied kinesiology and up your diagnostic ability yourself.
Ty fren! I agree
🫡
Shits awesome A dab a day for 5 days 1 tube is short for my weight but works just fine!