Levamisole Dosage Calculator For Dogs
Calculate targeted levamisole treatment dosages based on clinical parameters.
Dosage Recommendations
© medsdog.com
Levamisole dosage for dogs is a genuinely useful anthelmintic – but it also has one of the narrowest safety margins of any dewormer still used in dogs today. Getting the dose right isn’t a minor detail; it’s the difference between clearing a parasite infection and causing a toxic reaction. This guide walks through exactly how levamisole is dosed in dogs, what it treats, what can go wrong, and when it should be avoided altogether.
This article is based on Pet Owner Education. Not intended to replace veterinary attention. Levamisole should only be used under the direction of a licensed veterinarian after examining your dog.
Paid Links - As an Amazon Associate, I earn from qualifying purchases.
What Is Levamisole?
Levamisole for dogs is a synthetic imidazothiazole class anthelmintic (dewormer). It acts by stimulating the nicotinic acetylcholine receptors in the parasites and resulting in constant muscle contractions, paralysis and eventual death of the parasites. It has been used in livestock and to a lesser degree in dogs and cats for many years, having been developed by Janssen Pharmaceutica, Belgium, under various names including Ripercol or Tramisol in the 1960s.
Levamisole is sometimes also known as tetramisole, the racemic (“mixed-isomer”) form of the drug. Does not work on household pests, mites, ticks or fleas, only on roundworm-type parasites (nematodes).
Is Levamisole Approved for Use in Dogs?
First of all, you should know this: No levamisole product is made specifically for dogs in the United States and is FDA approved. All levamisole that your dog receives will be from one of two places:
- A compounded dosage form, such as capsules of a certain strength for your dog’s exact prescription, made by a licensed veterinary compounding pharmacy.
- An extra-label (off-label) use of a product that is formulated and approved for use on livestock, such as an injectable solution or oral bolus for cattle, sheep or pigs.
Both are commonplace in veterinary medicine; drug use is extra-label and legal when supervised by a veterinarian. However, it does mean two things for you as an owner; firstly, the dose needs to be calculated correctly, and not read off the label of a pre-measured product, and secondly, that you must have a prescription and veterinary supervision to use it safely and legally.
What Is Levamisole Used to Treat in Dogs?
Levamisole for dogs dosage has been used in dogs for control of the following parasites as determined from published veterinary dosing literature:
- Gastrointestinal roundworms (ascarids)
- Trichuris vulpis (canine whipworm)
- Crenosoma vulpis (a lungworm)
- Capillaria aerophila (a roundworm of the respiratory tract in the lungs and airways)
- A respiratory nematode (Oslerus osleri, filaroides osleri)
- Angiostrongylus vasorum (French heartworm/lungworm)
- Dirofilaria immitis — adult heartworms and circulating microfilaria, formerly thought to be the only cause
On that last point: Levamisole was a microfilaricide (a drug that clears the larvae heartworms in the bloodstream) before safer more targeted heartworm protocols became standard. Today’s approach to heartworm disease involves a combination of FDA-approved drugs and treatments such as macrocyclic lactone heartworm preventives and administration of levamisole (adulticide) under a specific protocol — don’t assume levamisole is always the correct drug to use in the treatment of heartworm.
Additionally, because of its effects on the function of lymphocytes, levamisole has been investigated off-label as an immune-modulating agent in dogs with generalized demodiciosis and lupus-like diseases. This use is not proven and is not “first line” therapy, but is included because it may be mentioned in other places.
Levamisole Dosage Chart for Dogs (by Parasite and Route)
How to Read This Table
Levamisole Doses for dogs are in mg per kg body weight (mg/kg), unless otherwise indicated. When a range of doses is provided (e.g., 5-16 mg/kg), this is due to real differences in published protocols and product labels and does not represent a lack of accuracy on our part. Your veterinarian will determine the exact number in that range, depending on the number of parasites, the formulation and your dog’s health.
| Route | Parasite / Indication | Dose | Frequency / Duration |
| Intramuscular | Roundworms | 5 mg/kg | Single dose |
| Oral | Gastrointestinal roundworms | 5–16 mg/kg | Single dose |
| Oral | Trichuris vulpis (whipworm) | 16 mg/kg | Single dose |
| Oral | Respiratory roundworms | 7.5 mg/day (fixed dose) | Once daily × 2 days |
| Oral | Crenosoma vulpis | 8 mg/kg | Single dose |
| Oral | Capillaria aerophila | 7–12 mg/kg/day | Once daily × 3–7 days |
| Oral | Filaroides osleri | 7.5–12 mg/kg/day | Once daily × 10–45 days |
| Oral | Dirofilaria immitis, microfilariae | 10 mg/kg/day | Once daily × 6–12 days |
| Oral | Dirofilaria immitis, adults | 10 mg/kg | Twice daily × 14 days |
| Oral | Angiostrongylus vasorum | 5–10 mg/kg/day | Once daily × 2 days |
| Subcutaneous | Filaroides osleri | 7.5 mg/kg/day | Once daily × 30 days |
| Subcutaneous | Roundworms | 5 mg/kg | Single dose |
This table is based on manufacturer’s and literature recommendations for susceptible parasites. All approvals are based on country and region and the veterinarian’s particular prescription would always supersede any general reference table, such as this one.
Oral Dosing
Pet dogs (mostly) are orally dosed, and the prescription will call for compounded capsules to be orally administered. Your vet will adjust the length of treatment according to how your dog reacts and the results of follow-up fecal or airway examinations, but for some conditions such as Filaroides osleri (chronic respiratory nematode infection), there is a wide range of possible length of treatment (10-45 days).
Injectable (Intramuscular and Subcutaneous) Dosing
The large animal formulation is usually the one to use and is injectable, being given off-label to dogs at a lower dose (5mg/kg of roundworm by either the IM or SC route) and just once. Some swelling at the injection site may occur, but will likely resolve in time. Doing this by injection should be left to the veterinary expert — it’s not something you can eyeball at home when calculating the volume of a livestock strength solution.
How to Calculate Your Dog’s Levamisole Dose (Step by Step)
If your vet has told you a dose per kg, and not a total number, here’s the exact math:
- Obtain an accurate current weight. Always use a recent vet-scale weight not a guess – this is the most common cause of dosing mistakes.
- Convert to kilograms if needed. 1 lb = 0.453592 kg. (10 lb dog ≈ 4.5 kg; 50 lb dog ≈ 22.7 kg.)
- Multiply weight (kg) by the mg/kg rate your vet prescribed for the specific parasite and route. Example: a 20 kg dog prescribed 8 mg/kg for Crenosoma vulpis needs 160 mg per dose.
- If the drug is administered more than once a day (such as 2 times daily heartworm adult dose), multiply by the frequency (4) to determine the total daily dose.
- Check against the strength of the formulation. For example, if you need 160 mg and only have 50 mg capsules, that is 3.2 of the capsules, and it may be worth flagging any dose that is not an even number of your formulation capsules and asking your pharmacy to prepare a custom compounded strength instead of just “eyeballing” a partial dose.
Enter your dog’s weight, route and the type of parasite your veterinarian will be administering and the calculator at the top of this page will automatically yield the amount per dose, amount per day and number of days of treatment according to the same table shown above.
Levamisole Forms Available for Dogs
Since there is no commercial product specifically for dogs, you will most likely find levamisole in one of these forms:
Paid Links - As an Amazon Associate, I earn from qualifying purchases.
- Oral capsules that are compounded and are regularly found in strengths of 50 mg, 100 mg and 250 mg, which are made to your dogs’s prescription from a legitimate veterinary compounding pharmacy.
- Injectable solution (not for livestock use) at a vet calculated volume.
- Oral bolus or drench (also for livestock, but not commonly used in dogs because of difficulty in accurately preparing doses at small-patient size).
Compounded medications are not FDA-approved medications on their own — they are made based upon a veterinarian’s prescription to fit the needs of a particular patient (for example, a strength that may not be available, or a form that your dog can take). A legitimate compounding pharmacy will need a patient-specific prescription, and should be licensed and accredited (PCAB is one indicator of quality control).
How Levamisole Is Given
- Oral: By mouth, usually one or two times a day, according to the protocol. Can be fed with or without meals, unless directed otherwise by your veterinarian.
- Intramuscular (IM): Injection into the muscles by a veterinary practitioner.
- Under the skin (SC): Injected under the skin which can result in a temporary swelling at the injection site.
Levamisole Side Effects in Dogs
Levamisole dog medication acts by stimulating nicotinic acetylcholine receptors; it is selectively active on receptors found in parasites, and at higher doses will stimulate receptors in the dog’s nervous system. Some dogs will have mild but self-limited reactions even with therapeutic doses that are correct:
- Drooling or excess salivation (mild)
- Fine tremors of the muscles, particularly of the face
- May have mild GI upset (vomiting, decreased appetite)
- Swelling at an injection site (in the case of SC/IM administration)
Usually temporary and will correct itself. Anything more than mild (refer to toxicity section below) is not a condition to “wait out at home”.
Levamisole Overdose and Toxicity in Dogs
This is where it’s all important. Levamisole has a small therapeutic window (therapeutic index), that is, a small margin of safety between a therapeutic dose and a toxic dose. Dogs have been reported to die when the therapeutic dose has been exceeded by about 10 times and there is no specific antidote.
Levamisole Toxicity symptoms:
Toxic effects are the continuation of a drug’s cholinergic effect and may involve:
- Overproduction of saliva and vomiting
- Shaking and twitching muscles
- Ataxia, or difficulty with coordination (stumbling)
- Urinating and defecating more often
- Restlessness, anxiety or over excitability
- Difficulty with quick or shallow breathing
- Severe cases: seizures, collapse, abnormal heart rhythm and respiratory failure.
One case series of three German Shepherd dogs has been documented, where an inappropriately high dose (approximately 80mg/kg, well outside of the therapeutic dose range) resulted in vomiting, bradycardia, tachypnea, and death within 2 days of the dose. It’s an example of why there’s no room for imprecise calculation based on weight with this drug.
What to Do If You Suspect an Overdose
If your dog has taken more levamisole dose than recommended, has ingested a levamisole-containing product that was not intended for it or is displaying one or more of the symptoms listed above:
- Don’t wait to see if symptoms get worse, contact your vet or emergency animal hospital.
- There is no specific antidote and treatment is supportive: IV fluids and seizure control and monitoring – all of which must be done in a clinical setting, not at home.
- Never try and make your dog vomit, nor try using any home remedy without veterinary advice, particularly if your dog is already displaying neurological symptoms.
Levamisole Drug Interactions
- Pyrantel and morantel: They work in a similar manner (both are nicotinic agonists). They should not be used in combination with levamisole as the effects are additive and the risk of toxicity is much greater. In other species, pyrantel has been found to reduce the toxic threshold of levamisole significantly.
- Anticholinesterase agents, such as organophosphates (found in some flea/tick products and pesticides) may increase the risk of cholinergic toxicity if used concurrently with levamisole. Before beginning levamisole treatment, let your veterinarian know if your dog is exposed to any flea/tick or pesticide products.
- Other cholinergic drugs, in general: Be sure to consult your veterinarian before using levamisole in combination with other drugs that affect the cholinergic nervous system.
It is important to provide your veterinarian with a complete list of all medications, supplements, and parasite prevention that your dog is taking before beginning levamisole treatment.
Who Should Not Receive Levamisole
Levamisole must be used with care, or avoided in dogs that are:
- Very weak or of poor general condition
- Taking certain other medications that can interact with the drug and cause side effects (the drug is also metabolized and excreted in the kidneys and liver)
- Pregnant animals or animals in lactation (Safety in these states has not been determined for use in veterinary medicine and is not approved for use in breeding or lactating animals)
- Has already been treated with pyrantel, morantel or is exposed to products containing an organophosphate (see interactions above)
This is a general safety guide and does not replace your dog’s specific veterinary evaluation — please make sure to discuss your dog’s complete medical history prior to treatment.
Why Levamisole Is Used Less Often Today
If your veterinarian goes for another dewormer as the first line of defense, it’s in keeping with the general trend in veterinary parasitology. Levamisole was used a lot less following the arrival of broad-spectrum anthelmintics which are more safe — namely benzimidazoles (such as fenbendazole) and macrocyclic lactones (such as ivermectin and milbemycin).
Those drug classes are deemed relatively safe over a much broader dose range and that is critical in small patients where the range for error is smaller when calculating dosage.
However, levamisole is not extinct. It’s still truly effective—especially for some less frequently used dewormers that don’t work as well against certain respiratory nematodes, and when resistance is an issue, especially with production animals. Today it is used on specific parasites (such as lungworms) and not for routine deworming, at least not in dogs.
Levamisole vs. Other Common Dog Dewormers
| Drug | Typical Use in Dogs | Relative Safety Margin | Prescription Status |
| Levamisole | Roundworms, whipworms, certain lungworms, historically microfilariae | Narrow — overdose risk is real | Compounded/off-label only; prescription required |
| Pyrantel pamoate | Roundworms, hookworms | Wide — adverse effects uncommon | OTC or prescription depending on product |
| Fenbendazole | Roundworms, hookworms, whipworms, some tapeworms, Giardia | Wide | OTC or prescription depending on product |
| Milbemycin/ivermectin (at labeled preventive doses) | Heartworm prevention, some intestinal parasites | Wide at preventive doses; narrower in specific breeds with an MDR1 mutation at higher doses | Prescription |
It is not a ‘levamisole is bad’ comparison, it is context. Levamisole is indicated for certain parasites (such as some types of lungworms) and for those parasites it is effective, but it’s not always the first, or even last, choice for the deworming program of a home or a clinic because it’s harder to manage.
Myth vs. Fact
Myth: “Levamisole is not just another dewormer that you can buy over the counter.
Fact: There is NO OTC, dog-specific levamisole product. Must be compounded (usually by vets) and prescribed.
Myth: “If a little is good, a little more can’t be bad.”
Fact: Levamisole drug is one of the less safe dewormers that is being used in dogs. Fatal toxicity has been reported in veterinary case reports following overdoses.
Myth: “Levamisole and cocaine on the internet equals it’s bad for pets.
Fact: Articles you may read about the use of levamisole as an adulterant in “street cocaine” are associated with a particular skin reaction (vasculitis) among drug users who use cocaine containing this adulterant. This is a completely different human-toxicology issue than levamisole’s approved, prescribed veterinary application as a dewormer for dogs. Don’t confuse the two, the veterinary dosing information in this article is not related to this human drug-contamination issue.
Myth: “An old drug that shouldn’t be used anymore.
Fact: It is used less these days due to the availability of newer dewormers with wider margins of safety but it is still a valid and effective choice for specific parasites (and sometimes those with lungworm) when properly dosed and prescribed by a veterinarian.
Cost and Where to Get Levamisole for Dogs
The cost of levamisole for dogs is not fixed as it is compounded and will be dependent on the veterinary compounding pharmacy compounding it, strength, and quantity; we won’t specify a price point as it’s subject to change depending on the supplier/region — ask your vet clinic or veterinary compounding pharmacy for the price.
The things that remain constant for reputable suppliers are that they’ll require a prescription from a licensed veterinarian for your patient, and they will be properly licensed (PCAB for example is a quality signal) to ship in the state(s) they operate in.
You May Also Like to Read:
- Ligaplex Dosage For Dogs: Calculator, Chart & Safe Guide
- Metamizole Dosage For Dogs: Calculator, Chart & Safe Guide
FAQs
What is levamisole used for in dogs?
Levamisole is an anthelmintic that treats some kinds of roundworms in dogs, gastrointestinal roundworms, whipworms, and some lungworms (Crenosoma vulpis, Capillaria aerophila, Filaroides osleri). It has also been historically used against microfilaria of heartworm.
Is levamisole safe for dogs?
It is safe when applied at the proper and veterinarian prescribed dosage level, but it has a less wide safety margin than many other dewormers. There is a risk of real toxicity with overdose (cardiac, neurologic), and accurate weight-based dosing and veterinary supervision are crucial.
What dosage of levamisole is an appropriate dose for my dog?
The dosage relates to the route of use and the specific parasite being treated and is from approximately 5 to 16 mg/kg depending on the indication. Always use your veterinarian’s prescription and only use a dosage calculator as a math-check against the prescription.
What are the symptoms of an overdose of levamisole in a dog?
Excessive salivation, vomiting, muscle tremors, uncoordinated movement, restlessness, rapid breathing and in severe cases, collapse and convulsions. It is an emergency — call your veterinarian or animal poison control hotline right away.
What is the treatment for levamisole poisoning in dogs?
There is no known antidote. Treatment consists of supportive care (IV fluids, control of seizures and monitoring) in a veterinary clinical setting.
Is it possible to use levamisole in conjunction with other dewormers?
No — avoid using in combination with pyrantel or morantel – these have a similar mode of action and using them together greatly increases the risk of toxicity. Be sure to let the owner know of any medications the dog is taking before beginning levamisole.
Can levamisole be used in pregnant or lactating bitches?
Not approved for use in pregnant or lactating animals and safety in these states has not been determined. If your dog is pregnant or lactating, discuss other options for parasite control with your veterinarian.
So why is it that more vets do not use levamisole today?
More recent anthelmintics such as fenbendazole and the macrocyclic lactones have much broader safety margins, and largely superseded levamisole for routine deworming. Levamisole has some activity and is still used for particular indications, namely for some lungworm infections.
How is levamisole given to dogs — a pill or a shot?
Both are used. The most frequently used oral compounded capsules are for pet dogs. There are also injectable (intramuscular or subcutaneous) formulations, usually livestock products which are given off-label, usually by the vet.
A course of levamisole lasts for how many days?
It depends on the parasite species — some require a single dose (as per published dosing literature); chronic respiratory nematode infections (e.g. Filaroides osleri) may need to be dosed daily for 10-45 days.
Does levamisole cure heartworm in dogs?
Traditionally it has been applied as a microfilaricide (for elimination of circulating larvae) and in older protocols, as an adult heartworm treatment. Modern heartworm treatment involves FDA-approved adulticide therapy and a specific plan of prevention — so consult your veterinarian to see if this is appropriate for your dog’s particular situation or not.
Why is it that levamisole and pyrantel are different?
They are both nicotinic acetylcholine receptor agonists, which cause paralysis of parasites, and that is why they should not be combined. Pyrantel is safer to use and has a broader margin of safety and is more commonly used as a routine first line dewormer, whereas levamisole is used with more caution for specific parasites.
Final Thoughts
Levamisole Dosage For Dogs is a legitimate dewormer that is effective against certain canine parasites but is not a “set it and forget it” dewormer. This is a drug where the dose-to-toxicity ratio is truly small, and if you get it wrong, there is no antidote (except to work directly with your veterinarian), and there are no shortcuts (except for the math); getting the dose (or weight) correct is all important.
Always use the calculator and chart on this page to double check your vet’s dose – never use the calculator in lieu of the dose.
