Amantadine for Dogs: Uses, Doses, and Safety

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-09-20

Amantadine is an N-methyl-D-aspartate (NMDA) receptor antagonist that veterinarians use as an adjunct analgesic in dogs with chronic pain, most often osteoarthritis and neuropathic pain. It is not a first-line painkiller and it is not a stand-alone treatment. In dogs it is used off label for pain, meaning the drug is not approved by the FDA for that purpose in this species, and it is almost always added to a multimodal plan that already includes a nonsteroidal anti-inflammatory drug (NSAID), gabapentin, or both. Because amantadine is a human-labeled drug, the dose your veterinarian prescribes should come from the product label or a recognized veterinary formulary, never from a human dosing schedule.

This article is educational and is not a substitute for veterinary diagnosis or treatment.

At a Glance

What Amantadine Is and What It Is Used For

Amantadine is a synthetic antiviral drug developed for influenza A in people. In human medicine it is also used to manage Parkinson's disease. In veterinary medicine it has a completely different role. It is used as an analgesic, specifically as an adjunct for chronic pain states that respond poorly to standard painkillers alone.

The reason amantadine helps with pain is its action at the NMDA receptor. NMDA receptors sit on nerve cells in the spinal cord and brain and are involved in a process called central sensitization. Central sensitization is the "wind-up" that happens when pain signals keep firing for weeks or months. The nervous system becomes more excitable and starts sending pain signals even when the original injury is quiet. This is one of the mechanisms behind chronic or maladaptive pain, and it is part of why long-standing osteoarthritis or nerve compression pain can be so hard to control [2].

By blocking NMDA receptors, amantadine reduces that wind-up. It does not numb the joint or block the nerve the way an NSAID or local anesthetic does. It works upstream, at the level of the spinal cord and brain, to calm an overactive pain pathway. That is why it is called an adjunct or add-on analgesic. It is meant to be layered on top of other drugs, not used instead of them.

The most common clinical situations where veterinarians reach for amantadine in dogs include:

• Chronic osteoarthritis that is not fully controlled by an NSAID alone
• Neuropathic pain, which is pain caused by damage or dysfunction in the nervous system itself
• Degenerative lumbosacral stenosis, a narrowing around the nerves at the base of the spine
• Cancer-related or post-surgical chronic pain that has a neuropathic component

A review of neuropathic pain management in dogs describes amantadine as one of the standard drugs used alongside gabapentin, pregabalin, and amitriptyline for these conditions [3]. The same review notes that neuropathic pain is often underrecognized in veterinary patients because dogs cannot describe their pain, so veterinarians rely on behavior, gait, and examination findings instead.

How Amantadine Works

To understand why amantadine is useful, it helps to know a little about how chronic pain differs from acute pain.

Acute pain is a normal alarm. You touch something hot, nerves fire, you pull away, the pain fades. The pathway is straightforward and short-lived.

Chronic pain is different. When pain signals keep arriving at the spinal cord for weeks or months, the receiving nerve cells change. They become more sensitive. They fire more easily and more often. Receptors called NMDA receptors become more active, and this drives the process of central sensitization [2]. The result is pain that persists, spreads, or appears without any new injury. This is sometimes called maladaptive pain because the nervous system has adapted in a way that no longer serves a protective purpose.

Amantadine is an NMDA receptor antagonist. It sits on the receptor and blocks the excessive activation that drives central sensitization. This is the same mechanism that makes it useful in human Parkinson's disease, where it also affects dopamine signaling, and it is the mechanism that veterinarians are targeting when they use it for chronic pain in dogs.

Because amantadine works at a different point in the pain pathway than NSAIDs (which reduce inflammation in the joint) or opioids (which block pain signals at the receptor level), it complements those drugs rather than replacing them. This is the core idea behind multimodal analgesia: hit the pain pathway at several points at once so that each drug can be used at a lower, safer dose.

A pharmacokinetic study in horses describes amantadine as an NMDA receptor antagonist used in combination with opioids and NSAIDs in humans and dogs for conditions associated with central sensitization [2]. That description matches how veterinarians use it in practice.

What Amantadine Does Not Cover

Amantadine is not a general-purpose painkiller. It will not control acute pain from surgery, trauma, or a sudden injury. It is not a substitute for an NSAID in a dog with osteoarthritis. It does not reduce inflammation. It does not provide the rapid relief that an opioid or a local anesthetic provides.

Amantadine is also not an antiviral treatment for dogs. Although it is an antiviral in humans, it is used in dogs for pain, not for influenza or any other viral infection. Do not give a dog amantadine because a human in the household has the flu.

Finally, amantadine is not a first-line drug. If a dog has chronic pain and has never been treated, the veterinarian will usually start with an NSAID, weight management, and physical rehabilitation. Amantadine enters the plan when those measures are not enough, or when the pain has a neuropathic component that NSAIDs do not address well.

Dosing: Follow the Label or a Veterinary Formulary

The single most important rule with amantadine in dogs is this: the dose must come from the product label or a recognized veterinary formulary, not from a human dosing schedule and not from an internet calculator.

Amantadine is a human-labeled drug. There is no FDA-approved veterinary product for pain in dogs. When a veterinarian prescribes it, that prescription is off label. Off-label use is legal and common in veterinary medicine, but it places the responsibility for dose selection on the prescriber, who will consult a veterinary formulary or the human product label and adjust for the dog's size, condition, and other medications.

Because the dose depends on the specific product, the dog's weight, and the clinical situation, this article does not provide a dose number. Giving a dose that is not sourced from the label or a veterinary formulary can cause harm. Ask your veterinarian for the exact amount, the exact product, and the exact schedule.

For context on how amantadine behaves in dogs, a pharmacokinetic study in greyhounds gave a single oral dose of 100 mg amantadine hydrochloride (mean 2.8 mg/kg) to five healthy dogs. The drug was well tolerated with no adverse effects observed. The mean peak plasma concentration was 275 ng/mL (range 225 to 351 ng/mL) at 2.6 hours, and the terminal half-life was 4.96 hours (range 4.11 to 6.59 hours) [1]. Those numbers describe drug levels in the blood, not a recommended dose. They are useful to researchers and veterinarians who want to understand how long the drug stays in the body, but they are not a prescription.

A randomized trial in dogs with degenerative lumbosacral stenosis used amantadine at 3 mg/kg by mouth in two different schedules, one group receiving it once daily with meloxicam and the other receiving it twice daily alone, for 21 days [4]. That study provides evidence that amantadine can improve gait in dogs with this condition, but the dose used in a research protocol is not automatically the dose your veterinarian should prescribe. The prescriber still needs to match the product and the dog.

How to Give Amantadine

Amantadine is given by mouth. It comes as capsules, tablets, and compounded liquids. A few practical points:

• Give it with food unless your veterinarian says otherwise. This reduces stomach upset.
• Follow the schedule exactly. If the prescription is once daily, give it once daily. If it is twice daily, space the doses about 12 hours apart.
• Do not double up if you miss a dose. Skip the missed dose and continue with the next scheduled dose, unless your veterinarian gives different instructions.
• Do not stop suddenly without talking to your veterinarian, especially if the dog has been on it for a long time.
• Keep the product in its original container, away from children and other pets.

How Long Until It Works

Amantadine is not a fast-acting painkiller. It is used for chronic pain, and the response builds over days to weeks. In the degenerative lumbosacral stenosis trial, gait analysis was performed at baseline, after 7 days, and after 21 days, which reflects the expectation that benefit accumulates over time [4]. If you do not see a change in the first day or two, that does not mean the drug is not working. Give it the full trial period your veterinarian recommends before judging the response.

Side Effects and What to Do About Them

Amantadine is generally well tolerated in dogs, but side effects do occur. The most commonly reported problems are agitation, gastrointestinal upset, and possible tremors.

Agitation

Some dogs become restless, pace, or seem anxious after starting amantadine. This is the most common behavioral side effect. In many cases it is mild and settles within a few days as the dog adjusts. If the agitation is severe, if the dog cannot settle at all, or if it interferes with sleep for the dog or the owner, call your veterinarian. A dose adjustment or a change in schedule may help.

Gastrointestinal Upset

Vomiting, diarrhea, and reduced appetite are possible. Giving the drug with food reduces the risk. If vomiting is persistent, if the dog stops eating, or if there is blood in the stool, stop the medication and contact your veterinarian.

Tremors

Tremors or muscle twitching have been reported. These can be mild and transient, or they can be a sign that the dose is too high for that dog. Any new tremor should be reported to your veterinarian promptly.

Hypoglycemia (Low Blood Sugar)

A case report describes a 14.5-year-old Labrador Retriever with chronic lumbosacral pain that was being treated with gabapentin, paracetamol, and amantadine. The dog was referred for episodic weakness and was found to have documented hypoglycemia. Initial testing, including blood work and an ACTH stimulation test, did not find another cause. Continuous glucose monitoring confirmed recurrent low blood sugar episodes. When amantadine was discontinued, the hypoglycemia gradually resolved, and no further episodes were reported over a 20-month follow-up [5]. This is a single case, and the authors note that insulinoma was not definitively excluded, but the temporal association between the drug and the low blood sugar, and the resolution after stopping it, suggests a possible link. If your dog on amantadine shows weakness, wobbliness, confusion, or collapse, seek veterinary care.

What to Do If You See a Side Effect

1. Note what you saw and when it started relative to the last dose.
2. Call your veterinarian. Do not adjust the dose on your own.
3. If the dog is collapsing, having a seizure, or struggling to breathe, go to an emergency clinic.
4. Keep the medication container with you so the veterinarian knows the exact product and strength.

Which Dogs Should Not Receive Amantadine

Amantadine is not appropriate for every dog. Your veterinarian will review the history before prescribing. Dogs that should not receive it, or that need extra caution, include:

• Dogs with known kidney disease. Amantadine is cleared by the kidneys, and reduced kidney function can cause the drug to build up in the body.
• Dogs with known liver disease.
• Dogs with a history of seizures, because amantadine can lower the seizure threshold.
• Dogs with heart disease, especially arrhythmias.
• Dogs that are pregnant or nursing.
• Dogs with a known allergy to amantadine.
• Very small dogs, where accurate dosing is harder and the margin for error is smaller.

The prescriber will weigh the risks and benefits for each dog. In some cases the benefit of better pain control outweighs the risk, and the veterinarian will proceed with a lower dose and closer monitoring.

Drug Interactions

Amantadine can interact with other drugs. The most relevant interactions for dogs include:

• Other drugs that affect the central nervous system, such as gabapentin, pregabalin, opioids, and amitriptyline. These are often used together with amantadine on purpose, but the combination can increase sedation, agitation, or tremors.
• Drugs that affect the heart, because amantadine can affect heart rhythm.
• Drugs that are hard on the kidneys, because amantadine is cleared by the kidneys and reduced kidney function can raise drug levels.
• Anticholinergic drugs, which can add to dry mouth, constipation, and urinary retention.

Always give your veterinarian a complete list of everything your dog takes, including prescription drugs, over-the-counter products, and supplements. Do not assume that a supplement is harmless just because it is natural.

How Amantadine Compares With Other Pain Options

Amantadine is one tool in a larger toolbox. Understanding where it fits helps you have a better conversation with your veterinarian.

NSAIDs

NSAIDs such as meloxicam, carprofen, and grapiprant reduce inflammation and are the foundation of osteoarthritis pain management in dogs. They work quickly and are well studied. Amantadine does not replace them. It is added when the NSAID alone is not enough. In the degenerative lumbosacral stenosis trial, one group received meloxicam plus amantadine and the other received amantadine alone, and the study was designed to see whether adding amantadine improved the response in dogs that had not done well on meloxicam alone [4].

Gabapentin and Pregabalin

These drugs are also used for neuropathic pain and are often combined with amantadine. A review of neuropathic pain in dogs lists gabapentin, pregabalin, amantadine, and amitriptyline as the mainstays of treatment [3]. Gabapentin and pregabalin tend to cause sedation and wobbliness. Amantadine tends to cause agitation. The side-effect profiles differ, which is one reason a veterinarian might choose one over the other or combine them at lower doses.

Opioids

Opioids such as tramadol, buprenorphine, and hydromorphone are used for acute and severe pain. They are not usually the first choice for long-term osteoarthritis management because of side effects and regulatory considerations, but they can be part of a multimodal plan. Amantadine is sometimes combined with opioids for chronic pain that has a neuropathic component [2].

Amitriptyline

Amitriptyline is a tricyclic antidepressant used for neuropathic pain in dogs. It is another adjunct, not a first-line drug. It is sometimes combined with amantadine, though the combination increases the risk of sedation and anticholinergic effects.

Non-Drug Options

Weight management, controlled exercise, physical rehabilitation, acupuncture, and joint supplements all play a role in chronic pain management. Amantadine is one part of a plan that should include these measures.

Monitoring: What to Track and When

Monitoring is how you and your veterinarian know whether amantadine is helping and whether it is safe. The table below lists the key parameters to track, why they matter, and how often to check them.

A few notes on monitoring:

• Pain scoring in dogs is imperfect because dogs cannot self-report. Use a validated scale and be consistent. The same person should score the dog each time if possible.
• Behavior changes are the earliest sign of a problem. If your dog becomes restless, paces, or seems uncomfortable in a new way, write it down and tell your veterinarian.
• Renal function matters because amantadine is cleared by the kidneys. A dog with reduced kidney function may need a lower dose or a different drug.
• Blood glucose monitoring is not routine for every dog on amantadine, but it is worth considering if the dog is on multiple medications or shows signs of low blood sugar. The case report of amantadine-associated hypoglycemia is a reminder that this is a possible, if uncommon, effect [5].

Clinical Relevance, Limitations and Common Mistakes

Amantadine is a useful drug in the right patient, but it is easy to use incorrectly. Here are the mistakes that matter most.

Mistake 1: Using amantadine as a first-line painkiller. Amantadine is an adjunct. It is added to a plan that already includes an NSAID, weight management, and other measures. Starting with amantadine instead of an NSAID in a dog with osteoarthritis is not the standard approach.

Mistake 2: Using a human dose. Amantadine is a human drug. Human doses are not the same as dog doses. The dose must come from the product label or a veterinary formulary, and it must be matched to the dog's weight and condition.

Mistake 3: Expecting immediate relief. Amantadine works over days to weeks. Owners who stop the drug after two days because they see no change may be giving up too early. Follow the trial period your veterinarian recommends.

Mistake 4: Ignoring behavior changes. Agitation is a real side effect. If your dog is pacing, anxious, or unable to settle, that is information your veterinarian needs. Do not wait for the next scheduled recheck if the behavior is severe.

Mistake 5: Skipping blood work. Amantadine is cleared by the kidneys. A dog with undiagnosed kidney disease may build up the drug and have more side effects. Baseline blood work and periodic monitoring are part of safe use.

Mistake 6: Combining drugs without telling the veterinarian. Amantadine interacts with gabapentin, opioids, amitriptyline, and other drugs. If another veterinarian or an emergency clinic prescribes something new, make sure they know the dog is on amantadine.

Mistake 7: Assuming the drug is working because the dog is "fine." Dogs are good at hiding pain. A dog that seems fine at home may still be painful. Gait analysis and pain scoring are more reliable than a casual impression.

Mistake 8: Stopping the drug suddenly. If amantadine is stopped, it should be done with veterinary guidance, especially after long-term use.

The limitations of amantadine are also worth stating plainly. It does not work for every dog. Some dogs show no improvement. Some dogs cannot tolerate it because of side effects. The evidence base in dogs is smaller than the evidence base for NSAIDs, and much of what veterinarians know comes from small studies, case reports, and extrapolation from human medicine. The degenerative lumbosacral stenosis trial enrolled 20 dogs, which is a meaningful but modest sample [4]. The pharmacokinetic study in greyhounds enrolled five dogs [1]. The hypoglycemia report is a single case [5]. These are useful pieces of evidence, but they are not the same as large, multi-center, placebo-controlled trials.

Individual cases need a veterinarian. This article is educational and is not a substitute for veterinary diagnosis or treatment.

Questions to Ask Your Veterinarian

Before starting amantadine, or if your dog is already on it, these questions will help you get clear answers:

1. Why are you recommending amantadine for my dog specifically?
2. What dose are you prescribing, and what source are you using for that dose?
3. What other pain medications is my dog on, and how do they interact?
4. What side effects should I watch for, and which ones mean I should call you right away?
5. How long should we try the drug before deciding whether it is working?
6. Does my dog need blood work before starting, and how often after that?
7. What should I do if I miss a dose?
8. What is the plan if amantadine does not help?

Frequently Asked Questions

What is amantadine used for in dogs?

Amantadine is used as an add-on analgesic for chronic pain in dogs, especially osteoarthritis and neuropathic pain. It is not a first-line painkiller and is usually combined with an NSAID, gabapentin, or both.

Is amantadine approved for dogs?

No. Amantadine is a human-labeled drug. Its use in dogs for pain is off label, which means a veterinarian prescribes it based on veterinary formularies and clinical judgment rather than an FDA-approved veterinary label.

What dose of amantadine is safe for my dog?

The dose must come from the product label or a recognized veterinary formulary, matched to your dog's weight and condition. This article does not provide a dose number because the correct dose depends on the specific product and the individual dog.

How long does amantadine take to work in dogs?

Amantadine is used for chronic pain and works over days to weeks, not hours. Give it the full trial period your veterinarian recommends before judging whether it is helping.

What are the side effects of amantadine in dogs?

The most common side effects are agitation, gastrointestinal upset (vomiting, diarrhea, reduced appetite), and possible tremors. A single case report describes hypoglycemia in a dog on amantadine that resolved after the drug was stopped [5].

Can I give my dog amantadine for the flu?

No. Amantadine is an antiviral in humans, but in dogs it is used for pain, not for influenza or any other viral infection. Do not give a dog amantadine because a person in the household has the flu.

Can amantadine be combined with other pain medications?

Yes, it is often combined with NSAIDs, gabapentin, and other drugs as part of a multimodal plan. Combinations increase the risk of side effects, so your veterinarian needs to know everything your dog is taking.

What should I do if my dog has a bad reaction to amantadine?

Call your veterinarian. If the dog is collapsing, having a seizure, or struggling to breathe, go to an emergency clinic. Do not adjust the dose on your own.

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Further Reading

• Amantadine, an N-Methyl-D-Aspartate antagonist, for treatment of chronic neuropathic pain in a dog.

Sources

1. Pharmacokinetics of oral amantadine in greyhound dogs.
2. Assessment of pharmacokinetic parameters, oral bioavailability, and physiological effects of amantadine in horses.
3. Managing Neuropathic Pain in Dogs.
4. Amantadine as a therapeutic option for neuropathic pain in dogs with degenerative lumbosacral stenosis.
5. Suspected amantadine-induced hypoglycaemia in a dog treated for chronic lumbosacral pain.