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What are the signs of overdose in dogs?
What happens if I deworm my dog and they don't have worms?
How to give deworming pills to dogs
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What are the symptoms of overdose of dewormer in dogs?
- By Deanne
-
- May 27, 2026
- 4 MIN READ
Keeping your dog protected from intestinal parasites is an essential part of being a dog parent. Regular worming treatment helps prevent harmful infestations and nasty diseases that can affect your dog’s health, digestion, and overall wellbeing. However, giving too much dewormer or using the wrong dosage can sometimes lead to serious side effects. Scroll for all of the medical instructions you need to give worm treatment safely to your dog, and how to spot if something has gone wrong.
Why does my pet need deworming?
A dewormer is a medication designed to kill internal parasites such as roundworms, tapeworms, hookworms, and whipworms. These medications come in several forms, including liquids, powders, injections, and worming tablets.
Many pet owners use wormer tablets as part of their dog’s routine healthcare schedule. When given correctly, they are generally very safe.
Problems can occur when:
• The dog receives an incorrect dosage - Instead use tailored dog worming treatment, Itch Wormer for Dogs which is delivered every month with the allocated dose for your dog’s weight and breed. • Multiple treatments are accidentally combined• A product intended for another animal is used• Sensitive breeds react badly to certain ingredients
What are the signs of overdose in dogs?
The signs of overdose can vary depending on the type of medication, how much they have and your dog’s size and health condition. Some symptoms may appear mild at first but worsen over time.Click on each side effect for more information
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Vomiting
One of the earliest and most common signs is vomiting. It’s normal for dogs to be unwell after taking worming tablets if the dose was correct and they have no allergies. Within a few hours of treatment, they might repeatedly throw up. If they don’t settle, persistent vomiting may indicate toxicity. Contact your vet if this happens!
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Diarrhoea
Digestive upset is another common issue. A dog ill after worming tablets may develop diarrhoea, sometimes accompanied by blood or mucus in severe cases.
This can quickly lead to dehydration if not treated promptly.
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Excessive drooling
Some dogs experience nausea after taking a strong worming treatment, leading to excessive salivation or foaming at the mouth.
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Loss of appetite
Dogs suffering from a dewormer overdose may refuse food or water. If your dog stops eating for more than 24 hours, speak to your vet immediately.
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Lethargy and weakness
A tired or unusually sleepy dog may be reacting badly to the medication. Weakness, difficulty standing, or reduced activity levels can all signal overdose symptoms.
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Tremors or seizures
In severe cases, neurological symptoms may occur. These include:
Muscle tremors
Twitching
Loss of coordination
Seizures
Certain breeds, especially Collies and related herding breeds, can be more sensitive to some ingredients commonly found in wormer tablets.
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Dilated pupils or vision problems
Some toxic reactions affect the nervous system and may cause abnormal eye movements, enlarged pupils, or temporary blindness.
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Difficulty breathing
Breathing problems are considered an emergency. If your dog struggles to breathe after a worming treatment, seek urgent vet care immediately.
Dogs ill after worming tablets - Why?
There are several reasons a dog may become unwell after taking worming tablets:
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Incorrect dosage - Giving medication based on guesswork rather than accurate body weight is a common cause of overdose.
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Double dosing - Sometimes family members accidentally administer the same dewormer twice without realising it.
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Sensitivity to ingredients - Some dogs have genetic sensitivities to ingredients such as ivermectin or moxidectin.
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Interaction with other medications - Combining parasite treatments with other medications can occasionally increase toxicity risks.
What happens if I deworm my dog and they don't have worms?
If you wrongly give your pet dewormer tablets, or you’ve done the opposite and gave them too high of a dose of worming treatment, then depending on how your dog is, you need to act quickly.
If your pet is acting off, contact your vet with all of these details
• The product name• Amount given• Time administered• Your dog’s weight• Symptoms observed
Do not induce vomiting unless advised - Some substances can cause additional harm if vomiting is forced.
Monitor your dog closely - Watch for worsening symptoms such as seizures, collapse, or breathing difficulties.
Bring the packaging - If visiting the vet, take the packaging for the worming treatment so the vet can identify the active ingredients quickly.
How to give deworming pills to dogs
Preventing problems is usually straightforward with proper care.
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Weigh your dog accurately - Always use your dog’s current weight before administering wormer tablets. This is easy at the vets since they have big floor scales for all dog weights and sizes.
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Follow instructions and never exceed the recommended dosage or frequency.
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Crushing the pill or hiding your dog’s worming tablet in their food or favourite treat is a great way to get them to take the entire thing. Here are some simple tips on how to give your dog a worming tablet!
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Store medication safely as dogs may accidentally chew through packets of worming tablets if left within reach.
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Only combine flea, tick, and worming products if experts say so, like the monthly Itch Flea and Wormer subscription instructs you on how to use flea and worming treatment on your dog safely.
Normal side effects of deworming
Not every reaction means overdose. Mild symptoms can occasionally occur after standard worming treatment, especially if your dog has a heavy parasite burden.
Temporary side effects may include:
• Mild diarrhoea• Reduced appetite• Slight tiredness
These symptoms typically resolve within 24 to 48 hours.
A properly dosed dewormer is an important part of keeping your dog healthy, but overdoses can lead to serious complications. Understanding the warning signs (like vomiting and diarrhoea to tremors and seizures) allows you to be clear on when to worry, and how to respond quickly when your dog is sick after worming tablets.
Our biggest tip is always follow dosage instructions carefully, use the correct wormer tablets for your dog’s size and breed, and contact your vet immediately if you suspect anything is wrong.
Protect your pet from worms.
Intestinal worms can cause serious health issues for your pet and your family, but with a regular de-worming schedule you can protect your pet, home and family from these persistent parasites.
Itch Wormer tablets kills all common intestinal worms and prevent larvae from hatching and multiplying, until your pet's next regular treatment.
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