Dog Bad After Worming? A Dog Professional Explains!

If the dog becomes infested with worms, worming is essential.

In many cases, however, worming is also given as a preventive measure. This is especially true for dogs that are out in nature a lot.

There they have a lot of contact with worms and parasites, which can lead to health problems. But the worming also causes some dogs to feel unwell.

In this article, you will find out why this is and what you can do about it.

In a nutshell: Why is my dog feeling bad after the wormer treatment?

The purpose of deworming is to ensure that the worms in the dog’s body die and are then excreted. This requires chemical substances, since the worms do not die naturally.

These chemical substances are not only harmful to the worms, but can also cause side effects in the dog, which is why your dog feels bad after the wormer.

Some dogs tolerate the wormer better, while other dogs briefly suffer from side effects such as diarrhea, vomiting or exhaustion and even cardiac arrhythmia.

It is important that the dog is observed so that action can be taken quickly if the condition deteriorates.

What are the side effects of a dewormer?

Deworming is always a physical strain on the dog. Because the wormer is a poisonous drug that is supposed to kill the parasites in the dog’s body.

Every dog reacts differently to the wormer. This is dependent on the dog’s own immune system.

The most common side effects include diarrhea and vomiting. This is a completely normal reaction of the body to eliminate the drug.

Itching is also more common and indicates a reaction of the immune system. This can sometimes be an indication of an allergy.

Dog sick after deworming – why and what can I do?

If the dog feels bad after a deworming tablet, this is not unusual at first. Many dogs respond to deworming with physical symptoms.

Deworming is a powerful drug and aims to kill all parasites in the dog’s body. This can quickly lead to side effects.

However, if your dog’s poor condition lasts for several days and is accompanied by symptoms such as diarrhea, vomiting, muscle tremors or hair loss, this is a sign that your dog is not taking the wormer well.

This could be due to an overdose of the dewormer on the one hand or to the health of your dog on the other.

Healthy, adult dogs usually tolerate the cure better than puppies or old, previously ill dogs whose immune systems are more vulnerable.

You can do that

The most important thing after administering the deworming tablet is that the dog is closely observed so that you can react quickly if the condition deteriorates.

Many dogs tend to be exhausted and tired. Puppies are particularly affected. However, that is no cause for concern. Sufficient rest and sleep help the dog to get back on its four legs quickly.

If vomiting occurs, the animal should be observed more closely. If the dog reacts with very strong and prolonged vomiting, a veterinarian should always be consulted.

If the vomiting occurs very shortly after taking the deworming tablet, it may be necessary to take a wormer again. However, this should always be discussed with the veterinarian.

In the event of diarrhea, care should be taken to ensure that the dog has a sufficiently high liquid intake so that the dog does not become dehydrated. Even when vomiting, the dog should drink enough.

If diarrhea lasts longer than 24 hours, the dog should be taken to a veterinarian. To soothe the dog’s stomach, it should be given a bland diet.

However, symptoms such as vomiting and gastrointestinal problems are rare and could possibly be a sign of an overdose.

Dewormer overdose – act immediately

Overdosing on the wormer can cause serious side effects such as muscle tremors, lethargy, and ongoing gastrointestinal discomfort.

Severe side effects include kidney problems, liver damage, and abnormal heart rhythms.

This is a clear sign that the body is overwhelmed with the drug and does not know how to deal with it. The body reacts violently.

In this case, a veterinarian should be consulted immediately.

However, such severe side effects are the exception rather than the rule, since they actually only occur in the event of an overdose. It is therefore important to always discuss the administration of the wormer with a veterinarian so that an overdose can be prevented.

However, since one can never completely rule out whether an overdose has occurred, the dog should always be closely observed after ingestion.

When does the dog start to improve after deworming?

Most dogs recover very quickly after deworming. Many are fit again after just a few hours and are romping around.

Other dogs, on the other hand, need a little longer to fully digest the anthelmintic.

After 1-2 days the dog should be back to normal. If this is not the case, a veterinarian should be consulted.

This can treat the symptoms in a targeted manner and thus help the dog to recover quickly.

How harmful are dewormers for dogs?

A wormer contains many chemical substances. These attack the worms. But the dog’s body also comes into contact with these chemicals, which is why many dogs show a reaction.

Very frequent administration of wormers over many years can damage the dog. Dewormers should therefore always be administered with caution.

However, not administering wormers in the event of a worm infestation is also not recommended. Because the worms also damage the dog’s body.

So it should always be weighed up whether a wormer makes sense or not. As a precautionary measure, deworming is not always beneficial, since infection can also take place shortly after the deworming has been administered.

Rather, wormers should be used in the event of an infestation. A stool sample can be used by the vet to determine whether the dog is infested with worms. This can prevent you from taking medication too often.


Worm cures have it all. Not only for the worms but also for the dogs. A dog’s physical reaction to the dewormer is relatively normal and nothing to worry about.

Rest, sleep, and enough water are the best helpers during this time. A veterinarian should only be consulted if the state of health deteriorates.

Since wormers are strong chemical drugs, you should only give them to your dog in the event of an acute worm infestation.

Has your dog ever been wormed and how did it react?

Mary Allen

Written by Mary Allen

Hello, I'm Mary! I've cared for many pet species including dogs, cats, guinea pigs, fish, and bearded dragons. I also have ten pets of my own currently. I've written many topics in this space including how-tos, informational articles, care guides, breed guides, and more.

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