Unfortunately, the Veterinary Medicines Directorate contacted me to tell me it was against the law to advertise this wormer since it was classed as ‘Prescription Only Medicine – Veterinarian, Pharmacist, Suitably Qualified Person (POM-VPS)’. and that ‘Products classed as POM-VPS can only be advertise in publications aimed at professional bodies and not to the general public’.

I was surprised they considered this page as advertising so I spoke to them and they advised me that I should not use the product’s brand name but could say ‘A product containing Flubendazole‘. As a result, I have removed the product name.

Before using medication to worm your chickens, it is best to check they need worming first by using a Worm Count Kit like this one. This is a simple test where a sample is sent off by post and the results are returned to you (usually by email) and will advise you whether or not you should worm your chickens.

In the United Kingdom, a product containing the anthelmintic (wormer) Flubendazole is currently the only licensed in feed product available for chickens. It is very effective at killing worms and their eggs. Worms can cause a huge amount of damage to chickens and cause many health problems. As a rule of thumb, if I have a sick bird, the first thing I consider is whether or not she was wormed recently before exploring other avenues because so many signs of illness can be as a result of worms.

Flubenvet direct life cycle of worms

The Direct Life Cycle

Worms lay thousands of eggs in a day that are not always visible in droppings. Eggs then either get picked up by birds scratching around the floor, eating from the ground or in their litter when housed (i.e. picked up directly) or are eaten by earthworms or other ‘hosts’ and passed on to our birds when they themselves get eaten (i.e. indirectly picked up).

These two routes of infection are called the ‘Direct Life-cycle’ and the ‘Indirect Life-cycle’ and can be understood better from the diagrams show that are kindly supplied by Elanco (formerly Janssen Animal Health) where two examples of direct infection and one indirect are shown.

Flubenvet indirect life cycle of worms

The Indirect Cycle

Worm eggs are destroyed by heat, drought, a hard frost and UV from direct sunlight. For this last reason, I keep grass short in runs over the hotter summer months where my hens graze so that worm eggs can be destroyed. Over the colder winter months or below 10 degrees Centigrade. Worm eggs cannot mature and therefore cannot become infectious so I test my hens with a worm count kit and worm if necessary in the Autumn as the temperature starts to drop and in the Spring when worms become active again.

This product containing Flubendazole that I’m not allowed to name is very effective and after the recommended 7 day treatment, chickens are free of worms and eggs. One thing to remember is that the thousands of eggs deposited via droppings (or coughed up in the case of Gape Worm) are still present in the environment so if the worm infestation is bad, you will need to repeat treatment after 3 weeks to break the cycle before the newly acquired worms (picked up from the eggs) have a chance to mature and lay eggs themselves.

The withdrawal period stated on the tub is nil for eggs from laying hens. This means that you can continue to eat eggs whilst your chickens are being wormed. I’m sure you won’t be eating your hens but they must not be slaughtered for human consumption during treatment. Treated birds may be slaughtered only after 7 days from the last treatment.

Where to buy

If you have a small flock, there is a 60g pack sufficient to treat around 20 large chickens. This comes with a handy little measuring scoop so that you can get the quantity right. One 6 g scoop treats 2 kg of food for chickens. This is the simplest way to worm and if you mix it as I suggest above with a little oil, you can be sure your chooks are getting the required amount. There is also a 240g tub or gamekeeper pack which is more suited to 50 birds or more and lasts longer.

Because of the tight regulations and a license that sellers need to hold (costing over £600 I was told by one company), both of these products are becoming harder and harder to buy. I bought a 60g tub in 1998 and paid £12.50. A year ago I bought another one and it was £70! Serious money.

The product containing Flubendazole can also be purchased pre-mixed in layers pellets on websites such as Amazon in 5 or 20Kg bags which is handy if you don’t want to mix it yourself.

I haven’t seen many places selling this product containing Flubendazole online and vets don’t usually stock it unless they specialise in poultry. The ‘regulations’ are pushing people to go to their vets or other suitably qualified people yet in fact if you chat to chicken keepers, they are being offered offer other large animal wormers containing Ivermectin instead that are often bought in large packs for use on farm animals. These haven’t been tested on chickens so you end up with vets advising anything from a 7 to 30 day withdrawal periods for eggs (depending on the view of the vet of what will be ‘safe’) and although this is perfectly legal, my personal opinion is that this is wrong when there is a tested product available.

How I mix this product containing Flubendazole

mixing flubenvet with layers pellets

Adding the ‘paste’ to the layers pellets before mixing well

If you but the pack or tub then it will come as a powder that must be mixed with your chickens feed. In order to get this to stick to my layers pellets, I mix it in a small tub with a little Olive or Cod Liver Oil. The ‘paste’ that this makes can then be poured over the right amount of (weighed) pellets in a bucket and mixed well. It sticks to the pellets and won’t fall to the bottom of the bucket like I suspect some of the powder would without the oil.

Remember to wear disposable gloves for safety (yes I know we forgot in the photos!) and follow the ‘operator warnings’ given by the manufacturers below at the end of this page. Remember to dispose of empty containers in the domestic refuse. Used containers should not be recycled.

Pre-mixed layers pellets of course are easier and layers feed lasts for around 6-8 months before starting to spoil so you can use it for further treatments during this time.

How often do I worm my Chickens

As you will see from my routine list of jobs and from what I said above, I check my chickens for worms using a worm count kit twice per year as a preventative measure. Following the results, I worm if necessary but I also worm new birds that we add to our flock or if I become suspicious of worms / ill thrift.

I rotate the runs my birds use so there is no build up of worms. I would suggest you check for worms every 3 months if your birds are on the same ground continuously.

In between times, I sometimes use Verm-X and Apple Cider Vinegar to help keep worm numbers down as well as keeping the grass short in the summer months to allow UV from the sun to kill worm eggs.

You can read more about worms on my worming chickens page


  1. can you use flubenvet poultry pellets 5kg for quails as well as chickens and what would be the dosage for quails?

    • I’m sorry I don’t know – It’s not tested for quail as far as I know. I would take a guess and say yes you can but ultimately a vet would need to advise you. Another one to consider would be Ivermectin which has dosage for Pigeons and other small birds but again isn’t licensed for food producing animals.

  2. I have been using Flubenvet 1% for years, however I now seem to not be able to get any. Do you know anywhere that sells this currently and may have stock or any information into why I can’t seem to find any?

    • They might have been brought up on Layers Mash.
      I would try this (assuming you can find it, it’s not very popular) and gradually switch them over. They will usually start eating pellets when they get hungry though!

  3. At what age should you start using Flubenvet and verm x. New to keeping chickens, have 4x 5week old pekins. Thank you

    • I normally put about 2% ACV into water.
      For garlic I normally add two crushed cloves in 6 litres of water. There is no set amount of course…

  4. Thx for your informative article. I have a flock with 7 week old chicks, layers and a cockerel and I am being given some new layers on Wednesday. I would like to worm them all with Flubenvet feed but is it safe for the chicks to eat this. Basically the question is what is the age can you start using Flubenvet please? Many thx.

  5. Hi, we have ‘rescued’ two bantams that were abandoned in our local woods. We have no idea how old they are or what breed (I’m still googling to find out!). Am I right in thinking that it would be a good idea to worm them as a matter of precaution? Also, what other health related precautions should we take, other than all of the general things regarding cleanliness etc. should I give them a flea treatment for instance? Thanks!

    • Firstly, I would check to see if they are cockerels – these are often dumped unfortunately and by next spring, they will be fighting.

      Yes, you can worm them using Flubevet – there is a shortage at the moment but it’s available pre-mixed in pellets.

      You can check between the feathers on their skin and around the vent for lice (fast moving, skin colour) but unless they have lice, there is no need to treat them. Chickens don’t get fleas.

      • Thanks for your response! One of them is definitely a hen as she laid one egg…but no more so far. The other one we think is a hen, she has hardly any comb (although I have no idea if this means anything!). I have got some Verm-x to start the worming treatment on a regular basis as the one we aren’t sure of is pulling her feathers out. I have dusted the new coop liberally with diatom powder and am going to dust the birds tomorrow.
        How will I know if he/she is a cockerel?

        • There’s normally a reason Nancy- so I would check through the list on poultrykeeper. The trouble is, it can take a while for them to come back into lay so you also have to be patient I’m afraid.

  6. i have 4 ex bats who are constantly hungry. I have checked their poo, can’t see any worms. Does that mean they don’t have any? Should I wait till October to worm them and how much per hen. The instructions are dosage for 20. Sometimes the egg white is quite watery, why is this. Thanks for you help

    • Ex Bats usually have a very good feed to egg ratio and they will eat well in order to produce all of those eggs they produce. Make sure you’re feeding pellets or mash with the correct protein levels (not kitchen scraps etc).
      Flubenvet isn’t measured per hen (each consumes a different amount) you just need to feed the correct amount in with their feed for 7 days. If you want to know how much this is, weigh out what you give them for a week and you’ll know how much to mix up with the Flubenvet when you give it. Remember hens consume more in winter as they eat to meet their energy requirements and in winter need to burn more calories to keep warm.

      Watery egg whites occur in older hens (particularly high production hybrids such as Ex-batts) but can also be as a result of having had a disease in the past such as Infective Bronchitis.

  7. Thanks for great article. I have recently lost a hen directly after worming with flubenvet (for the first time) – had previously used another type of wormer in the water but was advised flubenvet was better. This hen had always made a strange noise like a ‘snick’ I think it’s called. She was otherwise healthy, eating and laying …. Although she did stop laying about 5 days before worming. The other 3 girls seem to be fine. Any ideas if it’s related? Would hate to think I killed her by worming her!!

    • It could be a complete coincidence although, if a hen is heavily infested with worms, it is possible for them to die when wormed. This is because there are a lot of toxins given off when the worms die. I haven’t heard of it actually happening to anyone but I’ve read about it.

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